Effective Home Remedies for Staph Infection

Staph Infection Secrets By Dr. Walinski

Discover a Simple 3-Step Program to Permanently Eradicate Mrsa & Staph Infections Without Using Antibiotics. Here is what's provided in Staph Infection Secrets. Get Rid of Your Staph / Mrsa Infection. Best ways to quickly get rid of the most common conditions caused by Mrsa and Staph, such as: Impetigo, Cellulitis, Folliculitis, Boils / Carbuncles and more. An easy remedy for nasal infections than can completely eradicate the presence of the bacteria in less than 7 days. How to treat internal infections using a naturally occurring powerful antibiotic with a proven success rate. Learn how to get the most out of Western medicine learn what kinds of treatment is available and how to work with your doctor for best results.

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Exercise 20 Staphylococci

Staphylococci are ubiquitous in our environment and in the normal flora of our bodies. They are particularly numerous on skin and in the upper respiratory tract, including the anterior nares and pharyngeal surfaces. Some are also associated with human infectious diseases. Staphylococci are gram-positive cocci, characteristically arranged in irregular clusters like grapes (see colorplate 1). They are hardy, facultatively anaerobic organisms that grow well on most nutrient media. There are three principal clinically important species Staphylococcus epider-midis, Staphylococcus saprophyticus, and Staphylococcus aureus. S. epidemidis, as its name implies, is the most frequent inhabitant of human surface tissues, including skin and mucous membranes. It is not usually pathogenic, but it may cause serious infections if it has an unusual opportunity to enter past surface barriers, for example, in cardiac surgery patients or those with indwelling intravenous catheters. S. saprophyticus has...

Furuncles and carbuncles

Others who have furuncles (ie, family members, contact sports), and malnutrition 8-11 . When the subcutaneous infection extends to involve multiple furuncles, the lesions are called carbuncles. Carbuncles are often located in the back of the neck, posterior trunk, or thigh. This multiseptate coalescence of multiple abscesses can be painful, and constitutional signs and symptoms, including fever and malaise, often are present. Purulent material may be expressed from multiple draining sinuses. Severe complications of furuncular infections, such as bacterial endocarditis, have been reported 12 . If systemic involvement of any type is suspected, evaluation should include a complete blood count, blood cultures, and Gram stain and culture of purulent material. Small-sized furuncles usually can be managed by applying moist heat to encourage drainage. Incision and drainage is needed for carbuncles and larger furuncles 4 . Systemic antibiotics usually are reserved for individuals who have...

Experiment 201 Isolation and Identification of Staphylococci

The laboratory diagnosis of staphylococcal disease is made by identifying the organism (usually S. aureus) in a clinical specimen representing the site of infection (pus from a skin lesion, sputum when pneumonia is suspected, urine, spinal fluid, or blood). It should be remembered that either S. aureus or S. epidemidis may be harmlessly present on superficial tissues. Special care must be taken not to contaminate the specimen with normal flora, and laboratory results must be interpreted in the light of the patient's Figure 20.1 A rapid latex agglutination test for identifying Staphylococcus aureus. The top left and center wells are the positive and negative controls, respectively. The top right well is the positive reaction of the patient's isolate. clinical symptoms. The principal features by which staphylococci are recognized and distinguished in the laboratory include their microscopic morphology, colonial appearance on blood agar (especially hemolytic activity), coagulase activity...

Folliculitisfurunclescarbuncles

A carbuncle is a coalescent mass of deeply infected follicles or sebaceous glands with multiple interconnecting sinus tracts and cutaneous openings that drain pus ineffectively. Carbuncles usually occur in the thick skin on the back of the neck and the upper back. The lesions steadily worsen, with increasing pain, erythema, swelling, purulent drainage, and lateral enlargement. These lesions range from 3 to 10 cm in diameter. Fever and other systemic symptoms and signs are common. Folliculitis is often treated with frequent use of soap and water and the application of topical antibiotic agents such as mupirocin, clindamycin, erythromycin, or baci-tracin. Occasionally, the addition of a systemic antistaphylococcal agent is required. Furuncles and carbuncles often require incision and drainage. Along with mild cleans

Certain infectious and parasitic diseases A00B99

Streptococcus and staphylococcus as the cause of diseases classified to other chapters B95.6 Staphylococcus aureus as the cause of diseases classified to other chapters B95.7 Other staphylococcus as the cause of diseases classified to other chapters B95.8 Unspecified staphylococcus as the cause of diseases classified to other chapters

Detection of antimicrobial resistance

PCR-based methods for the detection of antimicrobial resistance have been applied to bacteria including methicillin-resistant S aureus, vancomy-cin-resistant enterococci, and multidrug-resistant N tuberculosis. Detection of resistance to antiviral agents by molecular methods has also been described for acyclovir-resistant herpes viruses and HIV resistant to reverse transcriptase inhibitors and to protease inhibitors. Currently, none of these assays are available commercially but they have been used in a number of reference and research laboratories. The identification of methicillin resistance in S aureus represents an ideal application of NAA methods because the reliable detection of methicillin-resistant S aureus using culture and susceptibility tests may be problematic because expression of resistance (mec A gene) is usually heterogeneous and is influenced by culture conditions, especially in strains with low-level resistance 99,100 . Multiplex PCR and RT-PCR allow the...

Hazard Identification

The function ofcollectins is usually measured in opsonization assays. Traditionally, MBL activity is determined in a yeast assay (Turner et al., 1985). Antimicrobial factors in the alveolar lining fluids (e.g., surfactants A and D) are also determined by opsonization. In the assays, the opsonized bacteria are usually Staphylococcus aureus (Coonrod and Yoneda, 1983).

Leukocyte Adhesion Deficiency I

Infection often progressively enlarge, and they may lead to systemic spread of the bacteria. Infections are usually apparent from birth onward, and a common presenting infection is omphalitis with delayed separation of the umbilical cord. The most frequently encountered bacteria are Staphylococcus aureus and gram-negative enteric organisms, but fungal infections are also common. The absence of pus formation at the sites of infection is one of the hallmarks of LAD I. Severe gingivitis and periodontitis are major features among all patients who survive infancy. Impaired healing of traumatic or surgical wounds is also characteristic of this syndrome (Anderson and Smith 2001).

Characteristics A Organism

S. aureus is a spherical gram-positive bacterium (coccus) that on microscopic examination appears in pairs, short chains, or bunched, grape-like clusters. Some strains are capable of producing a highly heat-stable protein toxin, which is capable of causing illness in humans. Other salient characteristics are that they are nonmotile and asporogenous capsules may be present in young cultures but are generally absent in stationary phase cells (9). Staphylococcus species are aerobes or facultative anaerobes and have both respiratory and fermentative metabolism. They are catalase positive and utilize a wide variety of carbohydrates. Amino acids are required as nitrogen sources, and thiamine and nicotinic acid are also required. When grown anaerobically, they appear to require uracil (10). Although the staphylococci are mesophilic, some strains of S. aureus grow at a temperature as low as 6-7 C. In general, growth of S. aureus ranges from 7 to 47.8 C, with an optimum temperature for growth...

Diagnosis of Human Illness

In the diagnosis of staphylococcal foodborne illness, proper interviews with the victims and the gathering and analysis of epidemiological data are essential. Incriminated foods should be collected and examined for staphylococci. The presence of relatively large numbers of enterotoxigenic staphy-lococci is good circumstantial evidence that the food contains toxin. The most conclusive test is the linking of an illness with a specific food or, in cases where multiple vehicles exist, the detection of the toxin in the food sample(s). In cases where the food may have been treated to kill the staphylo-cocci, as in pasteurization or heating, direct microscopic observation of the food may be an aid in the diagnosis. A number of serological methods for determining the enterotoxigenicity of S. aureus isolated from foods as well as methods for the separation and detection of toxins in foods have been developed and used successfully to aid in the diagnosis of the illness. Phage typing may also...

Vehicles of Transmission

Staphylococci exist in air, dust, sewage, water, milk, food, or on food equipment, environmental surfaces, humans, and animals. Humans and animals are the primary reservoirs. Staphylococci are present in the nasal passages and throats and on the hair and skin of 50 or more of healthy individuals. This incidence is even higher for those who associate with or who come in contact with sick individuals and hospital environments. Although food handlers are usually the main source of food contamination in food-poisoning outbreaks, equipment and environmental surfaces can also be sources of contamination with S. aureus. Human intoxication is caused by ingesting enterotoxins produced in food by some strains of S. aureus, usually because the food has not been kept hot enough (60 C, 140 F, or above) or cold enough (7.2 C, 45 F, or below).

Tests Used for Identification

Sometimes additional diagnostic features may be required to confirm S. aureus colonies because the inhibitors used may not completely prevent growth of other organisms, such as bacilli, micrococci, streptococci, and some yeasts. Microscopic morphology helps to differentiate bacilli, streptococci, and yeasts from staphylococci, which form irregular or grape-like clusters of cocci. Staphylococci may be further differentiated from streptococci on the basis of the catalase test, with the former being positive. Additional features are needed to differentiate staphylococci further from micrococci. Usually staphylococci are lysed by lysostaphin but not by lysozyme, and they can grow in the presence of 0.4 g mL of erythromycin. Micrococci are not lysed by lysostaphin, may be lysed by lysozyme, and will not grow in the presence of erythromycin. In a deep stab culture, micrococci will grow at the surface, whereas most staphylococci grow throughout the agar. Staphylococci will grow and produce...

Toxin Identification in Foods

The major problem of identifying enterotoxin in foods is the small amount that may be present in foods incriminated in foodborne outbreaks. The amount of enterotoxin that may be present in foods involved in food-poisoning outbreaks may be as little as 50 ng g of food, although the normal amount of toxin in foods involved in food-poisoning outbreaks is easy to detect, since the amounts are frequently larger. As toxin can be readily identified in sources containing bacterial counts that are or were at some time > 106 enterotoxigenic staphylococci organisms per gram of food, food samples containing such high counts are not acceptable. Marketable foods should contain no entero-toxin as demonstrated by rapid as well as classical methods. Most outbreaks of staphylococcal intoxication are caused by foods that do not receive a high thermal treatment staphylococci survive in sufficient numbers in these foods to form the toxin before the food is consumed. However, some heated foods have also...

Necrotizing fasciitis

Although uncommon, necrotizing fasciitis (NF) is an infectious diseases emergency. Predisposing conditions include diabetes mellitus, surgery, trauma, peripheral vascular disease, and injection drug use. Classification of this life-threatening infection has been proposed based on the microbiology of infection 40 . Type 1 necrotizing fasciitis refers to a mixed aerobic and anaerobic infection (ie, diabetic foot infection and Fournier's gangrene, for example). Facultative streptococci, staphylococci, enterococci, aerobic

Preventioncontrol Measures

Staphylococci are ubiquitous and are impossible to eliminate from the environment. The total destruction or significant reduction in the bacterial load in foods during growth, harvesting, processing, packaging, and storage prior to consumption has always been a general goal. However, the wide array of parameters for proliferation of foodborne pathogens is staggering. Some of the same methods for the control of organisms in the food supply are used separately or in combination in the preservation of foods. Staphylococci may be totally destroyed or injured when subjected to lethal or sublethal doses, respectively, of heat, cold, drying, irradiation, or chemicals. While total destruction of these organisms might be ideal, sublethal injury may occur, thus providing the organism an opportunity to recover and proliferate (9), if conditions are conductive. The phenomenon of sublethal injury and stressed cell rejuvenation has been examined by a number of investigators. Conditions that have...

Cell Physiology And Genetics Of Antimicrobial Drug Resistance

A classic example of a bacterium that depends on antibiotic modification is Staphylococcus aureus. Since the 1950s S. aureus has been known to produce the enzyme P-lactamase. This enzyme cleaves P-lactam rings, resulting in inactivation of P-lactam-based antibiotics (45,47). Bacteria can have decreased uptake of antibiotic as a result of reduced permeability of their outer layer. Pseudomonas aeruginosa and Escherichia coli have an outer membrane with low permeability to antibiotics (48). Because antibiotics must be able to penetrate the cell by means of bacterial porins, the diffusion rate of the drugs is altered by changes in these porin channels. Loss of the porin required for cellular entry of imipenem causes P. aeruginosa to develop imipenem resistance (48). Alternatively, cellular exiting of drug may be enhanced. Tetracycline resistance for a number of bacteria, including many enterobacteriaceae, some staphylococci, and some streptococci, results from active export of the...

Chronic Granulomatous Disease

Table 9-11 lists the reactions of the respiratory burst pathway. Organisms that make their own catalase are more often responsible for severe infections in these patients. These organisms are able to convert their own hydrogen peroxide to water, thus making it unavailable to the phagocyte for the microbicidal purpose. As a consequence, the ingested bacteria or fungi remain viable in the phagocytes and are protected from host humoral immunity and from antibiotics, which fail to penetrate the cell. The mobility of the phagocytes leads to generalized seeding of the reticuloendothelial system with live microorganisms. This results in the formation of generalized chronic granulomatous lesions, characterized by recurrent suppurative infection with bacteria of low virulence (e.g., Staphylococcus aureus, Staphylococcus epidermidis, Aerobacter aerogenes, and Serratia marcescens), Burkholderia (Pseudomonas) capacia and Salmonella, or infection with mycotic organisms (e.g., Aspergillus). S....

The organisms and special situations

The distribution of osteomyelitis is influenced dramatically by the age of the patient, the specific causative organism, and the presence or absence of any underlying disorder or situation. in infants and children, acute osteomyelitis most commonly is caused by hematogenous spread. Staphylococcus aureus is the most common causative agent, followed by b-hemolytic streptococcus, Streptococcus pneumoniae, Escherichia coli, and Pseudomonas aeruginosa 7,8 . The incidence of infection by Haemophilus influenzae has declined dramatically because of widespread HIB vaccination 8-10 . Although any bone can be affected, the most commonly involved are the metaphyses of long bones, especially the distal femur and proximal tibia, followed by the distal humerus, distal radius, proximal femur, and proximal humerus 11 . S aureus is also the most prevalent infecting organism later in life in osteomyelitis of the mature skeleton, and Gram-negative rods are found in the elderly. Fungal osteomyelitis is a...

Alternatives to Antigen Antibody Reactions

As a defense against host antibodies, some bacteria have evolved the ability to make proteins that bind to the Fc region of IgG molecules with high affinity (Ka 108). One such molecule, known as protein A, is found in the cell walls of some strains of Staphylococcus aureus, and another, protein G, appears in the walls of group C and G Streptococcus. By cloning the genes for protein A and protein G and generating a hybrid of both, one can make a recombinant protein, known as protein A G, that combines some of the best features of both. These molecules are useful because they bind IgG from many different species. Thus they can be labeled with flourochromes, radioactivity, or biotin and used to detect IgG molecules in the antigen-antibody complexes formed during ELISA, RIA, or such fluorescence-based assays as flow cytometry or fluorescence microscopy. These bacterial IgG-binding proteins can also be used to make affinity columns for the isolation of IgG.

Necrotic Enteritis

Sequencing studies of the cloned cpb gene (63) also revealed that this toxin shares 28 homology with another spore-forming toxin, Staphylococcus aureus a-toxin. Based upon this shared sequence homology and results from previous studies mapping S. aureus a-toxin structure function relationships, site-directed mutagenesis was performed on cpb (64). Those mutagenesis studies produced results supporting the hypothesis that C. perfringens P-toxin and S. aureus a-toxin share partial, although not complete, similarity in their structure and action. The previously mentioned findings (38) indicating that, like S. aureus a-toxin, P-toxin can oligomerize and affect membrane permeability properties in mammalian cells, provide some additional evidence that these two toxins share some similarities in their action and structure.

Covalently Attached Lipids Anchor Some Membrane Proteins

FIGURE 11-13 Membrane proteins with P-barrel structure. Five examples are shown, viewed in the plane of the membrane The first four are from the E. coli outer membrane. FepA (PDB ID 1FEP), involved in iron uptake, has 22 membrane-spanning fi strands. OmpLA (derived from PDB ID 1QD5), a phospholipase, is a 12-stranded fi barrel that exists as a dimer in the membrane. Maltoporin (derived from PDB ID 1MAL), a maltose transporter, is a trimer, each monomer constructed of 16 fi strands. TolC (PDB ID 1EK9), another transporter, has three separate subunits, each contributing four fi strands in this 12-stranded barrel. The Staphylococcus aureus -hemolysin toxin (PDB ID 7AHL top view below) is composed of seven identical sub-units, each contributing one hairpin-shaped pair of fi strands to the 14-stranded barrel.

Acute articular inflammation

An acutely inflamed joint must be considered septic until proved otherwise. Staphylococci, streptococci, and Haemophilus influenzae are frequent causes of septic arthritis in childhood. Lyme disease is a frequent infectious arthritis in areas where Ixodes ticks are endemic.

Selected Investigational Fibrinolytics

Staphylokinase Staphylokinase (SAK) is a single-chain, 136 amino-acid protein secreted by strains of Staphylococcus aureus and manufactured for clinical use by recombinant DNA technology (91,92). The SAK-plasmin complex is fibrin selective, efficiently activating plasminogen while bound to fibrin at the thrombus surface. SAK has shown at least equivalent reperfusion potential and greater fibrin specificity than accelerated dose tPA in phase 2 studies. SAK is antigenic, inducing neutralizing antibodies within 1 wk. A peglyated form has been generated to increase half-life and allow for bolus dosing.

Streptococci Pneumococci and Enterococci

The mucous membranes of the upper respiratory tract that are exposed to air and food (nose, throat, mouth) normally display a variety of aerobic and anaerobic bacterial species gram-positive cocci (Streptococcus, Staphylococcus, and Peptostreptococcus species) gram-negative cocci (Neisseria, Moraxella, and Veillonella species) gram-positive bacilli (Corynebacterium, Propionibacterium, and Lactobacillus species) gram-negative bacilli (Haemophilus, Prevotella, and Bacteroides species) and, sometimes, yeasts (Candida species). membranes show a predominance of staphylococci. The throat (pharyngeal membranes) has the richest variety of microbial species, and the sinus membranes have few if any organisms. The deeper reaches of the respiratory tract (trachea, bronchi, alveoli) are not readily colonized by microorganisms, because the ciliated epithelium of the upper membranes together with mucous secretions trap and move them upward and outward. to be beta-hemolytic. When growing on blood...

Experiment 212 The CAMP Test for Group B Streptococci

Group B streptococci can be distinguished from other beta-hemolytic streptococci by their production of a substance called the CAMP factor. This term is an acronym for the names of the investigators who first described the factor Christie, Atkins, and Munch-Petersen. The substance is a peptide that acts together with the beta-hemolysin produced by some strains of Staphylococcus aureus, enhancing the effect of the latter on a sheep blood agar plate. This effect is sometimes referred to as synergistic hemolysis (see colorplate 30). Demonstration sheep blood agar plate, streaked at separate points with Staphylococcus aureus, group B

Asymptomatic Bacteriuria

Asymptomatic bacteriuria (ABU) is defined by the presence of bacteria in the urine in a patient who does not have any symptoms (or, more generally, any clinical manifestations whatsoever) attributable to the bacteriuria, irrespective of the presence or absence of pyuria (1). At any point in time, ABU is present in a fraction of the healthy population, including males and females of all ages. However, the likelihood of ABU is greatest throughout life in females, and increases in both genders with advancing age and progressive debility (66). The spectrum of organisms causing ABU is generally similar to that of symptomatic UTI, with polymicrobial infection and certain bacterial species (e.g., enterococci, coagulase-negative staphylococci, and Gram-negative bacilli such as Providencia) encountered more frequently (66).

Experiment 213 Identification of Pneumococci

Pneumococci are among the most important agents of bacterial pneumonia. Other microorganisms such as staphylococci (Exercise 20), Haemophilus influenzae (Experiment 22.1), and Klebsiella pneumoniae (Exercise 24) may also be associated with serious pulmonary disease. Bacterial agents of pneumonia cause an acute inflammation of the bronchial and or alveolar membranes. When the alveoli are involved, their thin membranes may be disrupted by hemorrhage of alveolar capillaries and collections of inflammatory exudate (pus) containing many white blood cells. Laboratory diagnosis is often made by isolating the causative agent from sputum sent for culture. However, because sputum specimens pass through the oropharynx as they are expectorated, contaminating members of the normal throat flora may interfere with culture results by overgrowing the pathogen. The causative organism is often found in the bloodstream during early stages of infection, and therefore, patient blood should also be...

Chronic granulomatous disease CGD

Patients with the classic form of CGD develop serious infections usually within the first year of life. In most cases, infection is caused by catalase-positive bacteria, such as Staphylococcus aureus and the Gram-negative enterobacter-iaceae, Salmonella spp., Klebsiella spp., Aerobacter spp. and Serratia spp. However, infections with the fungi Aspergillus (usually fumigatus) and Candida sp. are also seen. Although severe, infection in CGD may be characterised initially only by malaise, low-grade fever and a mild leukocytosis (raised white cell count) or elevation in erythrocyte sedimentation rate. Organisms that produce H2O2 but are catalase-negative (e.g. Streptococcus sp., Pneumococcus sp., Lactobacillus sp.) are not major pathogens in CGD. This may be because the

The Postoperative Course

In the first few days, the nasal airway can collect a fi-brinous exudate that sets like jelly in a mold. We encourage our patients to sniff and douche in order to avoid this (Fig. 13.1a, b). The postoperative recovery period can be plagued by the repeated formation of crusts, which result from mucosal damage. Mucosal damage may be superficial, partial thickness, or full thickness (Shaw et al., 2001). Most nasal dressings cause superficial mucosal damage that results in mucus stagnation as there are few remaining functioning cilia that remain to clear any secretions (Shaw et al., 2000). If there is full-thickness mucosal damage it may take up to a year for the cilia start to function synchronously again (Shaw et al., 2001). With superficial mucosal damage it may take 2-3 weeks for the mucosa to recover. Similarly, if there has been a marked infection, (e.g., Staphylococcus within the mu-cosa in these patients pus can be seen oozing out of the mucosa minutes after it has been cleaned...

Steven Berk and James W Myers

Fortunately, infection is a rare complication of prosthetic devices. Despite the presence of infection, removal of these devices is not always possible or necessary. The introduction of foreign material enhances the pathogenicity of known pathogens and increases the potential of less virulent microorganisms to cause damage. Thus, Staphylococcus epidermidis is a very common organism in patients with prosthetic devices as compared with the normal healthy population. Fibronectin promotes adherence of sta-phylococci to chronically implanted devices. An extracellular substance called glycocalyx has been associated with coagulase-negative staphylococci including S. epidermidis. A polysaccharide adhesin facilitates adherence of staphylococci to foreign material and functions as an antiphagocytic capsule. The function of polymor-phonuclear leukocytes is also impaired in the presence of foreign bodies. There is deficient superoxide production, which leads to impaired killing of microorganisms....

Regulatory Factors Other Than PrfA Thus Far Implicated in the Control of L monocytogenes Virulence Gene Expression

Finally, a homologue to the AgrA regulator of Staphylococcus aureus has been identified in L. monocytogenes (Autret et al. 2003). AgrA plays an essential role in S. aureus virulence (Novick and Muir 1999), however loss of the agrA gene product in L. monocytogenes resulted in a moderate attenuation in L. monocyto-genes virulence. Mutants lacking agrA exhibited no obvious phenotype in tissue culture assays, but were approximately 10-fold less virulent than wild-type strains following intravenous injection of mice (Autret et al. 2003). The nature of the regulatory role played by AgrA within L. monocytogenes remains to be defined.

Prosthetic Heart Valves

The accumulative rate of prosthetic valve endocarditis (PVE) is 1.5-3 within 1 yr after valve surgery. This increases to 5.7 after 5 yr (17). Coagulase-negative staphylo-cocci are the predominant agent of PVE during the initial 2 mo of surgery and, in fact, are the most common organisms throughout the first year after a valve replacement. Thereafter, viridans streptococci, enterococci, S. aureus, and fastidious Gram-negative coccobacilli increase in prevalence. Gram-negative bacilli and fungal etiologies of prosthetic valve endocarditis are most common in the initial 2 mo after surgery. Nafcillin (or a first-generation cephalosporin or vancomycin if allergic) plus rifampin for 6 wk plus gentamicin for 2 wk. Rifampin plays a unique role in the eradication of staphylococcal infection involving prosthetic material combination therapy is essential to prevent emergence of rifampin resistance Methicillin-resistant S. aureus Coagulase-negative staphylococci

Clinical Description

Left-sided IE occurs more frequently than right-sided IE. Patients typically have underlying cardiac abnormalities (acquired or congenital), prosthetic valves, poor dentition, and or HIV infection. Dental, respiratory, genitourinary, or gastrointestinal procedures may also predispose high-risk patients (those with underlying valvular abnormalities). Infection with highly virulent organisms such as staphylococci and Pseudomonas spp. can cause IE in the absence of underlying risk factors or cardiac abnormalities (2,3,7,8).

Prosthetic joint infection

Total joint replacement infections can present as acute, fulminant illness with fever, joint pain, local swelling, and erythema when caused by relatively virulent organisms (e.g., S. aureus). Subacute presentations with gradually progressive joint pain and no fever suggest indolent infection with a relatively avirulent organism (e.g., Staphylococcus epidermidis). A painful prosthetic joint can be caused by both infection and noninfectious, mechanical loosening. Radiography, bone scan, leukocyte scans, WBC counts, and sedimentation rate are not diagnostic for infection. Therefore, the diagnosis of prosthetic joint infection rests on isolation of the pathogen by arthrocentesis or, occasionally, by exploratory arthrotomy. Staphylococci are the predominant organisms (S. epidermidis, 22 S. aureus, 22 ), with streptococci in 21 , gram-negative bacilli in 25 , and anaerobes in 10 of cases.

Antimicrobial Therapy Of Resistant Organisms

The current drug of choice for the treatment of MRSA IE is vancomycin. The addition of rifampin and gentamicin is recommended for PVE. Despite susceptibility of staphylococci to vancomycin, failure with this therapy has occurred. In addition, relapse rates up to 15 following appropriate courses of therapy have been reported (37). Recent studies have demonstrated efficacy of the new fluoroquinolones, primarily levofloxacin and trovafloxacin, against experimental MRSA IE (33,38-40). These drugs have been shown to be superior to the earlier quinolones, that is, ciprofloxacin, and potentially more effective than vancomycin. In addition, the excellent bioavailabil-ity, penetration into and bactericidal effects on vegetations, clearance of bacteremia, and minimal development of resistance have made the newer quinolones attractive therapeutic potential alternatives (33,38,39). However, additional clinical trials will be needed before quinolones are considered an acceptable standard of care...

Antimicrobial Prophylaxis

New, alternative therapeutic regimens for the treatment of IE due to resistant organisms such as MRSA and VRE are obviously needed. One agent recently approved for treatment of MRSA and VRE IE is quinupristin-dalfopristin (Synercid ). This drug is a semisynthetic streptogramin whose two components are synergistically bactericidal against a variety of Gram-positive bacteria. Anecdotal cases have reported successful eradication of VRE IE with Synercid , either alone or in combination with other antimicrobial agents (47,48). The treatment of MRSA IE in rabbits revealed efficacy equal to vancomycin with lower serum levels and easier penetration of cardiac vegetations (49). LY333328, a glycopeptide antibiotic, has been shown to be as effective as vancomycin in the treatment of MRSA IE in animals. Lysostaphin is a peptidase produced by S. simulans which is also being evaluated for the treatment of MRSA IE. Lypho-statin, either alone or in combination with vancomycin, appears to be more...

Use of Protein A in IEM

Protein A, obtainable as a purified product, is a Staphylococcus aureus bacterial cell wall protein that has the property of binding specifically to the Fc portion of IgG molecules (2) and can be used for precoating the grids prior to the ISEM procedure (7-9). This has the effect of increasing the amount of virus trapped to the grid by a modest amount but is useful when using antisera of low titre and can be used to detect distant serological relationships that would not be detected by normal ISEM (2).

Pathology caused by the cellmediated immune response

Superantigens The toxins of Staphylococcus aureus and Streptococcus pyogenes belong to a family of exotoxins which have a profound effect on the immune system. These bacterial superantigens promote cell-mediated immunity by stimulating T cell activation and recruitment to local sites of inflammation. The T cell-stimulating activity contributes to the pathogenesis of the respective diseases. Staphylococcus aureus isolated from skin lesions of patients with atopic dermatitis secrete large amounts of superantigen whilst those isolated from non-atopic (allergic) individuals do not Skin colonisation by Staph. aureus can cause severe exacerbation of atopic dermatitis Anti-Staph. aureus superantigen IgE has been found in patients undergoing exacerbation of atopic dermatitis due to Staph. aureus colonisation Peripheral blood basophils'armed'with anti-Staph. aureus superantigen IgE undergo degranulation and release histamine upon challenge in vitro with superantigen

Structure and Replication

The aerogenically transmitted influenza viruses normally replicate in the mucosa of the nasopharynx, resulting in a pharyngitis or at most a tracheobronchitis, after an incubation period of 24-72 hours. Pulmonary dissemination of the infection can result from an upper respiratory infection or manifest without one, whereby the prognosis in the latter case is less favorable. Pneumonia caused solely by the influenza virus is rare. As a rule, bacterial superinfections with staphylococci, streptococci, pneumococci, or Haemophilus bacteria are responsible. These infections, which used to be the normal cause of influenza deaths (Haemophilus influenzae in the Spanish flu of 1918), can be controlled with antibiotics.

From the Intestinal Tract

This exercise provides you with an opportunity to apply your knowledge of the Enterobacteriaceae to making a laboratory diagnosis of an intestinal infection. In Experiment 25.1 you will prepare a culture of your own feces and observe the normal intestinal flora on primary isolation plates. In Experiment 25.2 you will be given a pure culture of one of the Enterobacteriaceae as an unknown to be identified. Experiment 25.3 is an antimicrobial susceptibility test of your pure unknown culture. Here you should observe the differences in response of gram-negative enteric bacilli, as compared with streptococci and staphylococci studied earlier, to the most clinically useful antimicrobial agents.

Evaluation of Bactericidal Activity of Human Biological Fluids by Flow Cytofluorimetry

The ability of biological fluids to kill microbes is an important feature of the human immune system. Following incubation of fluorescein isothiocyanate-labeled Staphylococcus aureus with biological specimens and subsequent staining with propidium iodide, the proportions of killed bacteria were estimated by flow cytometry. FACScan is a simple, quick and reliable method to evaluate bactericidal activity of biological fluids. The results of the cy-tometric method correlated well with the results of the classic microbiological method. The proposed method is highly informative for evaluating bactericidal activity of sera in immuno-compromised patients. Bactericidal activity of biological fluids was investigated using fluorescein isothiocyanate (FITC)-labeled Staphylococcus aureus (S. aureus, Cowan I strain, Tarasevich National Institute for Drugs Standardization, Russia, Moscow). S. aureus cultures were washed, resuspended in carbonate-bicarbonate buffer and the concentration of...

Detection And Control Of Epidemics

In the event of increased rates of infection, it may be appropriate to identify asymptomatic carriers and isolate them in an attempt to disrupt the chain of transmission. For some infections (MRSA, multidrug-resistant S. pneumoniae, group A streptococci) decolonization with systemic or topical antimicrobial agents has been attempted to disrupt transmission and stop an outbreak. Consultation with an expert in epidemiology should be considered if reasonable measures are not effective. Failure to detect new cases indicates that the epidemic has abated and a return to routine infection control procedures can be considered.

Immunotherapy Of Specific Bacterial Infections

Staphylococcus aureus There have been a number of attempts to develop type-specific antibodies for use in the treatment of staphyloccal infections (1-4). Most of them have focused on the development of vaccines to induce immunity against staphylococci (1,2) or the use of nonvirulent staphylococci to colonize individuals and prevent colonization by virulent staphylococci (3,4). None of these strategies has been shown to be effective to date, although it should be possible eventually to develop a vaccine against staphylococcal antigens that could induce protective immunity against invasive disease. One such antigen would be the toxic shock syndrome toxin (TSST). Pooled immunoglobulins have been used in the treatment of staphylococcal-associated toxic shock syndrome (5,6). This appears to be a successful strategy in some cases, but Because staphylococci, especially S. aureus, have become increasingly resistant to antibiotics currently in use, emphasis should be placed on the development...

Clinical Relevance

Although antibiotics are necessary to treat infections in the elderly, their use may be excessive (6). In a study performed by Zimmer and colleagues (7), in 37.6 of cases, the evidence to start an antibiotic was considered inadequate. Of all antibiotic classes, cephalosporins were the most frequently overused (8). As a result of frequent antibiotic use in LTCFs, we are now challenged with the problem of increasing antimicrobial resistance (9). Nearly 10 years ago, it was articulated that LTCFs would become the reservoir for the evolution of antibiotic resistant genes (10). At that time, attention centered on methicillin resistance in staphylococci and third-generation cephalosporin resistance in enteric bacilli. Trimethoprim sulfamethoxazole (TMP SMX) resistance and aminoglycoside resistance in Gram-negative bacteria were recognized as significant problems for nearly 20 years (11,12). Geriatricians are now facing the fear of treating multiresistant organisms in a population that is...

Infection Control And Antibiotic

Clinicians should be ecologically responsible in their prescribing of antibiotics. The unnecessary use of broad-spectrum antibiotics to treat susceptible organisms should be strongly discouraged. There should be clear guidelines in place for using vancomycin in the nursing facility (e.g., MRSA, -lactam allergy, metronidazole failures in treatment of C. difficile colitis, or surgical prophylaxis in p-lactam-allergic patients). Limits to the length of antibiotic administration should also be enforced. Using third-generation cephalosporins and quinolones in LTCFs only when they are absolutely necessary in the treatment of UTIs or URI LRTIs may limit the emergence of multiresistant Gram-negative bacilli and VRE. Restricting antibiotic formularies for LTCFs has been suggested as a potential means to this end. Alerting physicians to the number of treatment courses of quinolones or advanced generation cephalosporins used can stem overprescribing. Treatment algorithms are not yet a common...

Bacterial Virulence Influences Outcome

S. aureus causes significant visual loss in more than half of endophthalmitis cases. This organism produces a panoply of virulence factors that are controlled by the quorum-sensing systems sar (staphylococcal accessory regulator) and agr (accessory gene regulator). In experimental models, eyes infected with wild-type S. aureus were significantly more virulent than S. aureus with mutations in agr, sar or both quorum-sensing systems. Mutants deficient in a- or (3-toxin expression were also less virulent than wild-type S. aureus, but not to the extent seen with the agr sar quorum-sensing mutant 10 . Recent studies examined the value of intravitreal immunoglobulin against sterile toxin-induced endophthalmitis. Pooled human immunoglobulin was reported to attenuate the toxic effects of culture supernatants containing S. aureus exotoxins 11 . Lysostaphin, an enzyme that lyses staphylococci, was also effective against antibiotic-resistant S. aureus in experimental endophthalmitis 12 . In the...

Multiple Intracellular Microbial Strategies

The reader should realize that the schematic subdivisions of methods of iron acquisition by microorganisms, even if useful for didactic reasons, are oversimplifications. For instance, many microbes utilize - in an apparently redundant manner - several of the outlined strategies according to their site of growth within or outside of the body. To give just two examples of very common pathogens Candida albicans can produce a hydroxamate siderophore, can lyse erythrocytes and bind haemoglobin, and can produce a ferric reductase Staphylococcus aureus can bind transferrin, can produce siderophores staphyloferrin A and B and can digest haemoglobin and haem.

Summary And Conclusions

Using both lux transposons and homologous recombination with luxCDABE cassettes, we have been able to generate a wide range of stable, highly bioluminescent Gram-negative bacteria with relatively little difficulty. The generation of highly bioluminescent Gram-positive bacteria has been much more laborious. In addition to Staphylococcus. aureus, we have used the modified luxABCDE operon to successfully transform strains of the Gram-positive bacterium Streptococcus pneumoniae, S. pyogenes, and Listeria monocytogenes. In each case, the Gram-positive bacteria carrying this modified lux operon are highly bioluminescent and can be monitored in vivo in animals. Furthermore, since plasmid loss in the absence of antibiotic selection has been shown to occur in animal models exceeding 48 h, we have recently constructed a number of luxABCDE transposons. These have been successfully used for stable transformation and for monitoring gene regulation in a

Vibrio metschnikovii

The first significant clinical isolate was described in 1981 (80). It was isolated from a positive blood culture of an 82-year-old woman who had peritonitis and an inflamed gall bladder. Since the patient did not have a history of recent travel or of having eaten shellfish or crabs, the source of the pathogen could not be identified. The pathogen was also isolated from a blood culture of a 70-year-old patient who had liver cirrhosis, renal insufficiency, and diabetes (81). The patient did not have a history of recent travel or of having consumed seafood and died 5 days after admission. Blood culture of an 82-year-old lady who had septicemia, respiratory problems, and infected leg lesions yielded V. metschnikovii (81). Swab samples of the leg lesion revealed mixed flora that included V. metschnikovii. Another case of mixed bacteremia in an 83-year-old female who developed high fever, chills, and malaise after being admitted to a hospital for a suspected heart attack was reported by...

Infections In The Bone Marrowstem Cell Transplant Recipient

Bone marrow transplantation is associated with a characteristic spectrum of post-transplant infectious complications that occur in relation to the time interval following transplantation (39). Although this was initially described in allogeneic transplant recipients, a similar pattern of infection, although with a decreased frequency, is found in autologous transplant recipients. The first three to four weeks after transplantation are characterized by marrow aplasia with marked neutropenia. Bacterial infections caused by common Gram-positive isolates such as S. aureus, coagulase-negative staphylococci, and a-hemolytic streptococci, and less commonly Gram-negative enteric organisms predominate in this period (40). With the administration of broad-spectrum antimicrobial agents, the normal colonizing flora, including anaerobes is ablated, and replaced by potentially more resistant bacterial isolates and fungi, especially Candida species, with subsequent infections caused by these...

Blood Component Therapy

(Table 26-11) bacteria, and protozoa. Careful donor selection and improvements in screening and blood product testing have largely eliminated this problem. The other infectious risk is bacterial contamination of the donor units of blood. Infection is most commonly due to Yersinia enterocolitica and other gram-negative organisms. Platelet units are most commonly contaminated with S. aureus, Klebsiella pneumoniae, Serratia marcenses, and Staphylococcus epidermidis. Parasitic infections that can be transmitted through blood transfusion are malaria, Chagas disease, and Babesia.

Arch G Mainous III and Claire Pomeroy

The rapidly expanding challenge of antibiotic resistance impacts on patients across the globe. As the new millennium dawns, drugs for the treatment of many illnesses are becoming limited, more expensive, or in some tragic cases nonexistent. As outlined in the preceding chapters, all medical practitioners must be aware of the implications of drug resistance when prescribing therapy. In its 1992 report, the Institute of Medicine identified antibiotic resistance as one of the emerging disease threats. Tuberculosis and cholera organisms once thought to be nearly eradicated have developed drug-resistant strains and threaten the health of millions of people. Bacteria such as pneumococcus, enterococcus, and Staphylococcus aureus have developed resistance at a rapid rate and across multiple antibiotics. It was reported in 1995 that antimicrobial resistance among six common bacteria in U.S. hospitals added more than 600 million per year in direct hospital charges (1).

Fred A Lopez MD Serge Lartchenko MD

Primary skin infections (ie, pyodermas) typically are initiated by some breach in the epidermis, resulting in infection by organisms, such as Streptococcus pyogenes and Staphylococcus aureus, that colonize the skin. Host-associated factors, such as immunosuppression, vasculopathy, neuropathy, or decreased lymphatic drainage, may predispose to skin infection. The clinical syndromes associated with skin infections are often characteristic and are defined most simplistically by anatomic distribution (Fig. 1). Although often mild and self-limited, skin infections can be more aggressive and involve deeper structures, including fascia and muscle. This article discusses skin and soft tissue infections, including impetigo, hair follicle-associated infections (ie, folliculitis, furuncles, and carbuncles), erysipelas, cellulitis, necrotizing fasciitis, pyomyositis, septic bursitis, and tenosynovitis.

Other Cell Wall Polyanionic Polymers Teichoic Acids and Lipoteichoic Acids

The ribitol-P polymer of the L. monocytogenes TA is covalently bound to the peptidoglycan by a linkage unit formed by two disaccharides bound by a molecule of phosphoglycerol. This linkage unit has the structure Glc( 1 3)-Glc(P 1 1 3)Gro-P-(3 4)ManNAc((3 1 4)GlcNAc (Kaya et al. 1985). The disac-charide formed by the two molecules of Glc is bound to the ribitol-P polymer whereas that containing the acetylated amino sugars binds via a 1,6-phosphodiester linkage to the MurNAc residue of the peptidoglycan. The L. monocytogenes linkage unit of the TA is more complex than that of the closely related bacteria B. subtilis and Staphylococcus aureus, which contain only one disaccharide (Navarre and Schneewind 1999 Neuhaus and Baddiley 2003).

Microbial Evasion Of Phagocytosis

Several species of bacteria have developed defense mechanisms that prevent phagocytosis or increase survival within the cell. Extracellular bacterial pathogens such as S. pneumoniae have developed a thick polysaccharide capsule that inhibits complement activation and phagocytosis. Other species (e.g., staphylococci) produce a thick fibrin coat of coagulase that retards phagocytosis.

Retinal And Vitreous Infections

Studies have shown that postoperative endophthalmitis is primarily caused by organisms that colonize the eyelids, conjunctiva, and nose, with 90 of culture-positive postoperative endophthalmitis cases caused by Gram-positive organisms, of which coagulase-negative staphylococci are the most common (16,17). The major host risk factors for the development of postoperative endophthalmitis include bacterial blepharitis, nasolacrimal duct infections, nasolacrimal duct obstruction, active nonocular infections, diabetes mellitus, and immunosuppression from any cause. Late or delayed-onset postoperative endophthalmitis can occur days to weeks and even years after surgery. The type of surgery appears to play a definite role in the development of these late infections, with glaucoma surgery being more frequently associated with late-onset postoperative endophthalmitis. Late infections can present very subtly or in a fulminant suppurative manner. The type of presentation is primarily determined...

Microbicidal activity

The microbicidal activity of macrophages is a major line of defence of higher organisms that can not be fully replaced by the sophistication of the specific aim of the immune response. Phagocytic and microbicidal activities have been reproduced in vitro using different micro-organisms as targets, including Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus, Klebsiella pneumonie, Clamidia psittaci, Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium

Severe Congenital Neutropenia and Kostmann Disease

During the first year of life, omphalitis, otitis media, upper respiratory tract infections, pneumonitis, skin abscesses, and liver abscesses occur commonly with positive cultures for staphylococci, streptococci, Pseudomonas, Peptostreptococcus, and fungi. Splenomegaly may be present. Other manifestations include the following

Of Bioluminescent Grampositive Bacteria

Over the past decade, there has been a dramatic increase in the number of antibiotic-resistant strains of Gram-positive bacteria causing serious, life-threatening diseases in humans. Many strains of Staphylococcus aureus, which cause a variety of diseases ranging from pyoderma to toxic shock syndrome, are methicillin and gentamicin resistant, with some strains also showing limited resistance to vancomycin. Such bacteria are a major problem in nosocomial, or hospital-acquired, infections. Streptococcus pneumoniae, M. tuberculosis, and enterococci are also showing resistance to a wide range or, in some cases, all conventional antibiotics (e.g., MRSA and vancomycin-resistant Recently, we have been able to construct a novel Photorhabdus luminescens lux operon, in which each gene (luxA-E ) has been modified by introducing a Gram-positive ribosome-binding site (RBS). This novel operon, when preceded by an appropriate promoter sequence on the broad host range vector, pMK4, allowed several...

Case 46 Diffuse Nodular Infiltrates Suggesting Bacteremia And Septic Lung Abscesses

Cannonball Infiltrates

The CXR shows nodules in both lungs (Fig. 46.2), which seem to be peripheral and of roughly equal size. The differential diagnosis would be cannon ball metastases though these are typically basal and of unequal size. This patient actually has Klebsiella bacteremia. In parts of South-East Asia, Burkolderia pseudomallei may result in the same CXR appearance. The other important etiologic agent is Staphylococcus aureus bacteremia.

Lymphoid Immunodeficiencies May Involve B Cells T Cells or Both

Patients with these disorders usually are subject to recurrent bacterial infections but display normal immunity to most viral and fungal infections, because the T-cell branch of the immune system is largely unaffected. Most common in patients with humoral immunodeficiencies are infections by such encapsulated bacteria as staphylococci, streptococci, and pneumococci, because antibody is critical for the opsonization and clearance of these organisms.

Phages and Pathogenicity

Ikeda Tomizawa Transduction

A phenomenon called lysogenic conversion is often involved in the modulation of host pathogenesis by phage. After incorporation of a temperate phage genome into the host chromosome, most prophage genes are silenced, especially those involved in virus morphogenesis and host cell lysis. In contrast, the genes needed to maintain the lysogenic state are normally expressed during lysogeny. However, bioinformatic analyses have demonstrated that many phage-encoded genes have unknown functions, and it is generally assumed that temperate phages can serve as vectors to introduce novel genetic information into their host that may enhance their fitness in certain environments. These coding sequences may themselves directly specify new properties or act by influencing the expression of existing genes. If this new environment happens to be the human body, the results can be dramatic. Table 13.1. shows several examples of pathogens, their prophages, and the toxins or virulence factors that are...

Providencia Stuartii Characteristics Alpha Hemolysis

Klebsiella Pneumoniae Tsi

Plate 1 Staphylococcus aureus in a Gram-stained smear from a colony growing on agar medium (left) and from the sputum of a patient with staphylococcal pneumonia (right). The organisms are gram-positive spheres, primarily in grapelike clusters. The pink cells in the right-hand photo are neutrophils. Plate 26 Coagulase test. The tube of plasma on the right was inoculated with Staphylococcus aureus. A solid clot has formed in this tube in comparison to the still liquid plasma in the uninoculated tube on the left. Courtesy Dr. E. J. Bottone. Plate 27 Novobiocin disk test for differentiating two coagulase-negative species of staphylococci Staphylococcus saprophyticus (left) and Staphylococcus epidermidis (right). The zone of inhibition around S. saprophyticus is less than 16 mm, which identifies this species by its resistance to the antibiotic.

Isolated angiitis of the central nervous systen is a recently recognized vasculitic disorder primarily involving the

Patients are initially given oral cyclophosphamide (2 mg kg daily) and oral prednisone (1 mg kg daily). The prednisone is changed to an alternate-day regimen in about 4 to 6 weeks, and then the dose is gradually tapered. Cyclophosphamide is continued for at least 1 year after complete clinical remission. Leukocyte count is a guide to cyclophosphamide dose adjustment, and one should aim to keep the neutrophil count above 3,000 mm 3 An increased risk for infection, especially with Pneumocystis carinii, and bladder cancer should be kept in mind at all times. When compared with oral cyclophosphamide and corticosteroids, pulse IV cyclophosphamide and corticosteroids are equally effective in achieving initial remission however, in the long term, treatment with pulse cyclophosphamide does not maintain remission or prevent relapses to the degree that oral cyclophosphamide treatment does. Methotrexate and azathioprine are alternatives to cyclophosphamide in less severe forms of...

Bacterial Toxic Shock Is Caused by Superantigens

A number of bacterial superantigens have been implicated as the causative agent of several diseases such as bacterial toxic shock and food poisoning. Included among these bacterial superantigens are several enterotoxins, exfoliating toxins, and toxic-shock syndrome toxin (TSST1) from Staphylococcus aureus pyrogenic exotoxins from Streptococcus pyrogenes and Mycoplasma arthritidis supernatant (MAS). The large number of T cells activated by these superantigens results in excessive production of cytokines. The toxic-shock syndrome toxin, for example, has been shown to induce extremely high levels of TNF and IL-1. As in bacterial septic shock, these elevated concentrations of cytokines can induce systemic reactions that include fever, widespread blood clotting, and shock.

Bacterial and Algal Cell Walls Contain Structural Heteropolysaccharides

Pentaglycine Amino

Staphylococcus aureus Staphylococcus aureus FIGURE 7-22 Peptidoglycan. Shown here is the peptidoglycan of the cell wall of Staphylococcus aureus, a gram-positive bacterium. Peptides (strings of colored spheres) covalently link N-acetylmuramic acid residues in neighboring polysaccharide chains. Note the mixture of l and d amino acids in the peptides. Gram-positive bacteria have a pentaglycine chain in the cross-link. Gram-negative bacteria, such as E. coli, lack the pentaglycine instead, the terminal d-Ala residue of one tetrapeptide is attached directly to a neighboring tetrapeptide through either l-Lys or a lysine-like amino acid, diaminopimelic acid. FIGURE 7-22 Peptidoglycan. Shown here is the peptidoglycan of the cell wall of Staphylococcus aureus, a gram-positive bacterium. Peptides (strings of colored spheres) covalently link N-acetylmuramic acid residues in neighboring polysaccharide chains. Note the mixture of l and d amino acids in the peptides. Gram-positive bacteria have a...

Haemophilus influenzae

Haemophilus Satellite Cells

B Satellite colonies of Haemophilus influenzae surrounding the Staphylococcus aureus streak. S. aureus provides small amounts of V factor. The blood agar contains free X factor. H. influenzae is a facultative anaerobe requiring growth factors X and V in its culture medium. The X factor is hemin, required by the bacteria to synthesize enzymes containing heme (cytochromes, catalase, oxidases). The X factor requirement is greatly reduced in anaerobic culturing. The V factor was identified as NAD or NADP. A standard blood agar plate does not contain sufficient free V factor. Some bacteria, in particular Staphylococcus aureus, produce excess NAD and even secrete this coenzyme into the medium. That is why H. influenzae can proliferate in the immediate vicinity of S. aureus colonies. This is known as the satellite phenomenon (Fig. 4.21b). The medium normally used to culture H. influenzae is chocolate agar containing sufficient amounts of the X and V factors.

Neutral Mg2dependent Sphingomyelinases nSMase

A whole group of sphingomyelinases found in bacteria are structurally related to nSMase 1 53, 60 . In this sense they can be called neutral sphingomyelinases, although in practice they show a rather wide range of pH optima, and hydrolyze phospholipids other than sphingomyelin. These enzymes have been found in Bacillus cereus, Staphylococcus aureus ( 5-toxin), Listeria ivanovi, Leptospira interrogans, Chromobacterium violaceum, Helicobacter pylori and Pseudomonas TK4 73-77 . Of these, the nSMase from B. cereus is the best known. A distant evolutionary relationship has been noted between bacterial sphingomyelinase and mammalian DNase I 78 residues of DNase I that are involved in the active center (including His 134 ad His 252) are conserved in bacterial sphingomyelinase, and are essential for activity. They correspond to the essential His 136 and His 272 in nSMase 1 60 . Bacterial sphingomyelinases may be descendants from the eukaryotic enzymes, as proposed by Heinz et al. 79 for...

Complement Deficiencies

Complex diseases, individuals with such complement deficiencies may suffer from recurrent infections by pyogenic (pus-forming) bacteria such as streptococci and staphylococci. These organisms are gram-positive and therefore resistant to the lytic effects of the MAC. Nevertheless, the early complement components ordinarily prevent recurrent infection by mediating a localized inflammatory response and opsonizing the bacteria. Deficiencies in factor D and properdin early components of the alternative pathway appear to be associated with Neisseria infections but not with immune-complex disease.

Image Of Positive Catalase Test

Enterococcus Catalase Test

With a sterilized and cooled inoculating loop, pick up a small amount of the Staphylococcus culture from the nutrient agar slant. Smear the culture directly onto the left-hand side of the slide. The smear should be about the size of a pea. Figure 18.1 Slide catalase test. Staphylococcus epidermidis on the left produces a strong positive catalase reaction. Figure 18.1 Slide catalase test. Staphylococcus epidermidis on the left produces a strong positive catalase reaction.

Differential Characteristics

Coagulase Test Igg Clumping Factor

S. aureus is differentiated from the other staphylococcal species by a combination of the following features colonial morphology and pigmentation, production of coagulase, thermonuclease, acetone, P-galactosidase, phosphatase and a-toxin (hemolysin), acid from mannitol, maltose, xylose, sucrose, and trehalose, novobiocin resistance, presence of ribitol teichoic acid, protein A, and clumping factor in the cell wall. The ultimate species identification may be established by DNA-DNA hybridization with reference strains. A nonisotopic DNA hybridization assay and a polymerase chain reaction (PCR) procedure have been used to successfully identify S. aureus. Thermonuclease (16) is also frequently used as a simple, rapid, and practical test for routine identification of S. aureus. Coagulase and heat-stable nuclease tests are very efficient for the identification of foodborne S. aureus strains isolated on Baird Parker agar. However, the use of the coagulase and or thermonuclease test may...

Internalization of human pathogens into growing plants

The internalization of human pathogens into the endophytic microflora of plants has been viewed with skepticism (Lund, 1992). Considering that enteric pathogens are more adapted to the gastrointestinal tract of animals it is difficult to envisage how they could compete with endogenous soil bacteria when colonizing plants. Furthermore, the constitutive plant defenses would be considered sufficient to suppress such saprophytes. However, there is accumulating evidence to suggest that human pathogens can be integrated into the endophytic microflora of plants (reviewed by Warriner et al., 2003a). Indeed, it is now emerging that the endophytic microfloras of many plants contain opportunistic animal pathogens such as Enterobacter amnigenus, E. cloacae, Stenotrophomonas maltophilia, Staphylococcus xylosus, Staph. epidermis, B. cereus and Ochrobactrum anthropi. The occurrence of Staphylococcus within endophytic populations is surprising considering this is a normal commensal of the skin....

Evaluation of Suspected Immunodeficiency

Dihydrorhodamine Test

Abnormalities in Toll-like receptor (TLR) function recently has been defined in patients with a specific pattern of bacterial infections (Ku et al. 2005). These findings suggest that additional innate immune defects impacting this early response pathway are likely. Innate immune defects affecting neutrophil function typically result in cutaneous and deep-seated abscesses, pneumonia, periodontitis, and osteomyelitis (Rosenzweig and Holland 2004). These infections are often caused by characteristic bacteria (e.g., Staphylococcus aureus and Serratia marcesens) and or fungi (e.g., Aspergillus and Nocardia species). Congenital defects in specific complement components often are associated with autoimmunity as well as recurrent bacterial infections similar to the antibody deficiencies (Walport 2001). In addition, abnormalities of the late complement components are associated with a unique increase in susceptibility to Neiserrial infections (Figueroa and Densen 1991).

Antibacterial and Antiviral Effects of Epigallocatechin Gallate

Demonstrable antimicrobial activity by EGCG has been reported against a wide variety of microorganisms, including Chlamydia trachomatis, Chlamydia pneumoniae (Yamazaki et al., 2003) and Helicobacter pylori (Yanagawa et al., 2003). EGCG has also been considered to have an antiviral activity, as shown by its potent effect in vitro in HIV-1 (Yamaguchi et al., 2002). Furthermore, a number of laboratories reported that a variety of nonspecific cytokines induced by EGCG have direct antimicrobia1 activity against various microorganisms, including common extracellular bacteria like staphylococci, streptococci or even fungi. EGCG treatment of Lp-infected macrophages resulted in enhanced production of TNFa, which markedly inhibited Lp virulence activity. Specifically, a report published in 2002 showed that the growth of Lp in permissive macrophages was selectively inhibited by small amounts of EGCG, the major active green tea catechin. This antimicrobial activity was not due to direct effects...

Macrolide Antibiotics

Hemiketal Macrolide

Erythromycin is a mixture containing principally erythromycin A, plus small amounts of erythromycins B and C (Figure 3.65). Erythromycin activity is predominantly against Grampositive bacteria, and the antibiotic is prescribed for penicillin-allergic patients. It is also used against penicillin-resistant Staphylococcus strains, in the treatment of respiratory tract infections, and systemically for skin conditions such as acne. It is the antibiotic of choice for infections of Legionella pneumophila, the cause of legionnaire's disease. Erythromycin exerts its antibacterial action by inhibiting protein biosynthesis in sensitive organisms. It binds reversibly to the larger 50S subunit of bacterial ribosomes and blocks the translocation step in which the growing peptidyl-tRNA moves from the aminoacyl acceptor site to the peptidyl donor site on the ribosome (see page 408). The antibiotic is a relatively safe drug with few serious side-effects. Nausea and vomiting may occur, and if high...

Surface Proteins with Noncovalent Association to the Cell Wall

The peptidoglycan is a highly dynamic macromolecule whose structure is continuously modified by hydrolytic enzymes, also known as autolysins (Holtje 1998 Popowska 2004). These enzymes cleave preexisting linkages and act coordinately with biosynthetic activities during the incorporation of nascent peptidoglycan or the separation of daughter cells upon cell division. Hydrolytic enzymes are also responsible for the active release of cell-wall components (up to 30-50 per generation in some bacteria) and, as in the case of gram-negative bacteria, for the active recycling of peptidoglycan turnover products. Hydrolytic enzymes necessarily have to be subjected to tight temporal and spatial control since their indiscriminate activity may lead to cell lysis. The profile of autolytic enzymes in a given bacterium is assessed by zymogram assays using gels loaded with cell walls. Renaturated proteins displaying cell-wall degrading activities are visualized following gel staining. Zymogram assays...

The Effects of EGCG on Chemokine Production by Legionellalnfected Dendritic Cells

It is also important to note that upregulation of various parameters often associated with a heightened immune response is not always beneficial to the host in combating microbial infection. Sepsis is a severe and systemic illness caused by the excessive inflammatory response to microbial infections, often with fatal results. Both Gram-negative and Gram-positive bacterial infections are capable of causing sepsis. In this respect, medicinal properties of plant-derived agents need to be considered from the aspect of not only their ability to stimulate immune activity but also their possible role in downregulating excessive inflammatory responses. Ginsan, an acidic polysaccharide prepared from Panax ginseng appears particularly effective in this regard. Mice treated with ginsan before bacterial challenge with Staphylococcus aureus (S. aureus) are reportedly highly protected from sepsis-induced death while still maintaining antibacterial capacity. Interestingly, the phagocytic activity of...

Escape from the Primary Vacuole 921 Macrophages

Cereus Toxin

The weak activity of LmPI-PLC differentiates it from the classical bacterial PI-PLCs from Bacillus species and Staphylococcus aureus, which have strong activity on GPI-anchored proteins (Low 1989 Wei et al. 2005b). Although LmPI-PLC shares only 24 identity with PI-PLC from B. cereus (BcPI-PLC), the overall three-dimensional structures are highly homologous (Moser et al. 1997). Both consist of a single (Pa)8-barrel domain. The active site pocket is highly conserved with only two differences in amino acids involved in inositol binding, but complete conservation of the residues thought to be involved in catalysis. An important structural difference is the absence in LmPI-PLC of the Vb -strand of BcPI-PLC, which supports the edge of a shallow groove extending from the active site pocket and is predicted to promote interactions with the glycan of GPI-anchored proteins (Figure 9.1.) (Moser et al. 1997). Removal of the Vb -strand of BcPI-PLC resulted in somewhat decreased activity on PI and

Incorporation Of Antibiotics Into Biomimetic Coatings

The final loadings at same antibiotic concentration in PS-HA coating were 10 times lower than in biomimetic CA coating. Tobramycin could be adsorbed onto the PS HA coating, but the adsorption remained superficial and limited to low amounts. On the contrary, antibiotic molecules were coprecipitated with the crystals of the biomimetic CA coating, throughout the whole layer. Tobramycin did not change the morphology of the coating, but its thickness decreased with the increase of the amount of incorporated antibiotic. The dissolution of the coating and release of tombramycin were measured in vitro in SPS at pH5.0 and pH7.3. The release of the antibiotic was gradual, and faster at pH7.3 (50 ig ml min) than at pH5.0 (4 ig ml min). Tobramycin released from the biomimetic coating could inhibit growth of Staphylococcus aureus bacteria in vitro, indicating that the biomimetic CA coating containing antibiotics could be used to prevent post-surgical infections in orthopaedic and trauma.

Surface Proteins Anchored Covalently

Srtb Gene Svpa Listeria

Staphylococcus aureus has a second sortase, SrtB, which recognizes a sorting motif different than LPXTG. This sortase specifically cleaves an NPQTN motif in a surface protein involved in iron transport, IsdC (Mazmanian et al. 2002). L. monocytogenes has also an alternative SrtB sortase (Bierne et al. 2004). Like in S. aureus, the L. monocytogenes srtB gene maps in an operon containing two genes encoding the Lmo2185 (formerly SvpA) and Lmo2186 (SvpB) proteins, which share homology to S. aureus IsdC. Lmo2185 and Lmo2186 bear as putative sorting motifs NAKTN and NKVTN (NPKSS), respectively. Although a direct proof of their covalent anchoring to the peptidoglycan has not been yet shown, both proteins are detected in highly purified peptidoglycan material (Calvo et al. 2005) (see Sect. 5.5.1). Furthermore, Lmo2185 displays a unique migration on gels when extracted from peptidoglycan material (Bierne et al. 2004), suggesting that this species may correspond to the processed form covalently...

Box 113 Biochemistry In Medicine

Cystic fibrosis (CF) is a serious and relatively common hereditary disease of humans. About 5 of white Americans are carriers, having one defective and one normal copy of the gene. Only individuals with two defective copies show the severe symptoms of the disease obstruction of the gastrointestinal and respiratory tracts, commonly leading to bacterial infection of the airways and death due to respiratory insufficiency before the age of 30. In CF, the thin layer of mucus that normally coats the internal surfaces of the lungs is abnormally thick, obstructing air flow and providing a haven for pathogenic bacteria, particularly Staphylococcus aureus and Pseudomonas aeruginosa.

Ami and Auto GW Proteins Involved in Adhesion and Invasion

Of the Staphylococcus aureus Atl autolysin, while its C-terminal domain is anchored to the bacterial cell wall by eight GW domains (Milohanic et al., 2001). Ami exhibits lytic activity on L. monocytogenes cell walls (McLaughlan and Foster, 1998), but also mediates bacterial adhesion to target cells within an AinlAB background (Milohanic et al., 2001). ami mutants are attenuated in a mouse model of infection, indicating that Ami plays an important role in virulence (Milohanic et al., 2001). Auto is another L. monocytogenes GW-anchored autolysin that is absent from the L. innocua genome (Cabanes et al., 2004). Inactivation of aut decreases L. monocytogenes invasiveness in nonprofessional phagocytes however, expression of Auto in L. innocua does not confer an invasive phenotype, indicating that Auto is necessary but not sufficient for inducing entry (Cabanes et al., 2004). Interestingly, over-expression of Auto on wild-type L. monocytogenes also impairs invasion, suggesting that its...

Clinical Manifestations 21 Orofacial Infections

Sialadenitis, or infection of salivary tissue, is relatively common in the elderly, often from ductal obstruction caused by calculi, dehydration, sialogogic drugs, or general debility. In suppurative parotitis, there is a sudden onset of firm, erythematous swelling of the pre- and postauricular areas that extends to the angle of the mandible. This is associated with exquisite local pain and tenderness. Systemic findings of high fevers, chills, and marked toxicity are generally present. Progression of the infection may lead to massive swelling of the neck, respiratory obstruction, septicemia, and osteomyelitis of the adjacent facial bones. Staphylococci have been the predominant isolates, but Enterobacteriaceae, oral anaerobes, and other Gram-negative bacilli have also been reported.

Exercise 16 Primary Media for Isolation of Microorganisms

Simulated fecal suspension, containing Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus Mannitol salt plate streaked with Staphylococcus aureus on one side (pure culture), Escherichia coli Eosin methylene blue plate streaked with Staphylococcus aureus and Escherichia coli

Infections In The Solid Organ Transplant Recipient

The etiologic organisms are often dictated by the site of infection in the solid organ transplant recipient (22-25). Skin infections are very common, although rarely life threatening. The most common causative agents are viral, such as herpes simplex virus (HSV) and varicella zoster virus (VZV), with other agents such as Papillomavirus and various dermatophytes being less common. The skin may also represent a target organ for disseminated infection, with a variety of bacterial (including atypical mycobacte-ria), fungal, and viral etiologies. The incidence of wound infections varies with the type of transplant, being most common in liver transplant recipients. Although S. aureus is the most common wound isolate, Gram-negative enteric organisms, coagu-lase-negative staphylococci, and rarely Mucor may also be etiologic.

Antibacterial activity

Naidu and co-workers (1990 1991) have identified specific LF-binding proteins in Staphylococcus aureus isolated from human and animal infections as well as among various species of coagulase-negative staphylococci causing bovine mastitis. Apo-bLF at concentrations of 0.1 -0.4 could convert compact colonies of Staphylococcus haemolyticus transient to diffused in soft agar (Godo et al., 1997). This surface-active property of LF has prevented autoaggregation of cocci in compact ball-like colonies by hydrophobic interaction or trypsin-sensitive proteins. In vivo anti-staphylococcal activity of hLF, bLF and bLF hydrolysate was reported in an experimental mouse model (Bhimani et al., 1999). All the LF preparations demonstrated weak in vitro antibacterial activity while holo-LFs showed no activity. LF-treated mice (1 mg, i.v.) when injected with 106 staphylococci, showed 30-50 reduction in kidney infections, and viable bacterial counts in the kidney decreased 5- to 12-fold. The inhibitory...

Host Response in Endophthalmitis

Despite immune privilege, ocular inflammation in response to an invading bacterial pathogen occurs and can be either acute or chronic. Acute inflammation is most commonly associated with more virulent bacteria (B. cereus, E. faecalis, and S. aureus) and a poor visual outcome 10 . As early as 48 h after infection, both anterior and posterior segments are involved resulting in corneal edema, cellular infiltration within the cornea and aqueous humor, vitritis, and retinal periphlebitis 4 . In contrast, chronic inflammation is associated with less virulent bacteria (P acnes and Staphylococcus epidermidis), and a better visual outcome 4 . The onset of chronic inflammation is commonly delayed and clinically much milder.

Viruses Bacteria and Fungi

Tuberculosis, cholera, anthrax, diphtheria, gonorrhea, and tetanus are all caused by bacteria. Food poisoning is caused by the bacterial organisms Salmonella, Staphylococcus, and Clostridium. Rickettsiae, minute bacteria that dwell in the bodies of arthropods, cause two serious diseases Rocky Mountain Spotted Fever and Tsutsugamuchi Fever.

Discitis And Osteomyelitis

Vertebral Osteomyelitis Phlegmon

Spinal infections most commonly result from hematog-enous spread although they may also occur by traumatic or iatrogenic inoculation (during an invasive procedure) or uncommonly by extension from an adjacent infection (39,40,46). The hematogenous route typically originates from a genitourinary, gastrointestinal, skin, or respiratory source. Diabetics, intravenous drug abusers, and patients with chronic diseases such as sickle-cell anemia and acquired immunodeficiency syndrome (AIDS) particularly are prone to developing infections (38,40). Bacteria are the most common causes of spinal infections, with Staphylococcus aureus identified in 55-80 of cases (40,45,46). Parasitic and fungal infections are uncommon while viral infections are seen in greater frequency in AIDS patients (40).

Resistant Pathogens As A Cause Of Nosocomial Infections

The observation that infections acquired in the hospital tend to be caused by pathogens that are more resistant to antimicrobials than organisms causing similar infections originating in the community was made decades ago. Two factors seem to account for this difference. First, nosocomial infections tend to be caused by pathogens that are intrinsically more resistant to antimicrobials than pathogens that cause community-acquired infections (4). While community-acquired pneumonia is most often caused by Streptococcus pneumoniae, mycoplasma, chlamydia, Haemophilus influen-zae, and, in certain geographic areas, Legionella, nosocomial pneumonia is more likely to be caused by the more antibiotic resistant S. aureus and Pseudomonas aeruginosa (4). Similarly, community-acquired urinary tract infections are primarily caused by Escherichia coli and Staphylococcus saprophyticus, while nosocomial urinary tract infections will more frequently have enteroccocci or Pseudomonas aeruginosa as the...

Antimicrobial Agent Susceptibility Testing and Resistance

Wide variety of antimicrobial agents. Although new antibiotics continue to be developed by pharmaceutical manufacturers, the microbes seem to quickly find ways to avoid their effects. Two important bacteria that have developed resistance to multiple antimicrobial agents are Staphylococcus aureus strains, especially those resistant to the drug methicillin and its relatives, and Enterococcus spp. resistant to vancomycin. These organisms are referred to as methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE), respectively. Methods for identifying staphylococci and enterococci are described in detail in Exercises 20 and 21, but antibiotic-resistant strains of both organisms play important roles in infections acquired by hospitalized patients. The laboratory must use methods to detect this resistance so that special precautions are quickly instituted to prevent transfer of the resistant bacteria among patients.

Epidemiology and Etiology of Endophthalmitis

The majority of reported endophthalmitis cases follow intraocular surgery. The incidence of postoperative endophthalmitis (POE) following ocular surgery is low, at approximately 0.01-0.05 1 , but recent reports indicate that the incidence after cataract surgery is increasing 2 , with many isolates becoming resistant to prophylactic antibiotics 3 . The most common organisms associated with POE are those capable of colonizing the eyelid margin and the tear film. Coagulase-negative staphylococci, commonly found as normal flora of the ocular environment, cause the majority of acute endophthalmitis following cataract surgery. Other organisms frequently encountered include Staphylococcus aureus, viridans streptococci, other Gram-positive bacteria, and Gram-negative bacteria. Clinical outcomes of POE caused by non-coagulase-negative staphylococci are generally worse than those caused by coagulase-negative staphylococci 3, 4 . Late-onset POE may occur weeks to several months following...

Resistance In Grampositive Bacteria

2.1. fi-Lactam-Resistant Staphylococci Penicillin resistance in staphylococci dates back to the 1950s (24). Hence, it is now rare to find staphylococci susceptible to penicillin. Despite its prevalence, the ubiquitous nature of penicillin resistance in staphylococci should not be accepted with complacency. The staphylococcal penicillinase (PC1) is an inducible -lactamase exo-enzyme. Four variants (A-D) exist. The staphylococcal penicillinase genes are carried on plasmids and transposons and can be readily spread to other strains of sta-phylococci and possibly even to enterococci (25). The semisynthetic penicillins (nafcillin, oxacillin, methicillin, cloxacillin, and dicloxacillin) are resistant to the action of staphylococcal penicillinases. The -lactamase inhibitors (clavulanate, sulbactam, and tazobactam) are also effective inhibitors of PC1 -lactamase. The medicinal chemist has exploited the use of a p-lactam with a -lactamase inhibitor to create a potent combination (26). Hence,...

Specific Inanimate And Animate Vectors

Colonized bum wounds with multiply resistant S. aureus (MRSA) heavily contaminate their immediate environment (48,49), leading to cross-infections in other patients in the unit. Similarly patients having pneumonia with MRSA can heavily contaminate their surroundings (14). While health care worker colonization with MRSA is infrequently a source of patient infections, certain health care workers do seem to have a tendency toward shedding the organism into the environment and transmitting the resistant bacteria to patients (50,51). Such transmission appears to be more likely when the health care worker has an upper respiratory tract infection or chronic dermatitis.

Antibiotic Control Policies

With the increase in methacillin-resistant Staphylococcus aureus (nearly 40 of all S. aureus isolates in large hospitals) and our current limited treatment options limited to vancomycin, restriction policies are present in most hospital systems (35). In a large community hospital system, pharmacists placed a point-of-care reminder detailing the Centers for Disease Control guidelines for prudent use of vancomycin in all patient charts over a 1-yr period (36). During this time, appropriate use of vancomycin increased from 59 to 80 , and the use of vancomycin decreased by 75 .

Typical Food Poisoning Outbreaks

Contamination of the chicken probably occurred when it was deboned. The chicken was not cooled rapidly enough because it was stored in 12-inch-deep layers. Growth of the Staphylococcus probably occurred during the period when the food was kept in the warm classrooms. Prevention of this incident would have entailed screening the individuals who deboned the chicken for carriers of Staphylococcus, more rapid cooling of the chicken, and adequate refrigeration of the salad from the time of preparation until its consumption.

Pelvic Inflammatory Disease

C. trachomatis and N. gonorrhea are well-documented causes of PID. One recent randomized, controlled trial found that identifying and treating women with chlamy-dial cervical infections reduced the incidence of PID (65). PID is frequently a polymicrobial infection with bacteria such as M. hominis, H. influenzae, G. vaginalis, staphylococci, Group B streptococci, E. coli, and anaerobes (66). Thus, the consensus is that PID necessitates broad-spectrum antibiotic therapy. Anaerobes are particularly frequent in women with TOA and with PID in the presence of HIV infection or bacterial vaginosis (64,66). There is an association between bacterial vaginosis and PID, but its significance is controversial.

Characteristics of Bacteria

Spirilla Bacteria Shape

Bacteria resemble plants in that they have rigid cell walls, although the walls are generally of nitrogen rather than cellulose. Some forms have flagella, while others are nonmotile. Bacteria have ribosomes and nucleic acids but lack mitochondria, plastids, and the central vacuole. Bacteria are distinguished from each other, in part, on the basis of their shapes. Rod-shaped bacteria are called bacilli, round forms are called cocci, and curved forms are called spirilli. Cocci can occur in pairs (diplococci), clusters (staphylococci), or chains (streptococci). Staphylococcus

Case 8 Active Pulmonary Tuberculosis

Cavitating Lung Lesion Wegener

The CXR shows bilateral upper lobe infiltrates with cavities, suggestive of active pulmonary tuberculosis. In general, thin-walled cavities (< 5 mm) tend to be infective and, when thick-walled (> 10 mm), squamous cell carcinoma of the lung enters into the differential diagnosis. Tuberculosis tends to afflict the upper lobes and apical segment of the lower lobes. However, within the upper lobe, anterior segment involvement is rare. Diagnosis is confirmed by obtaining sputum and staining with fluorochrome or Zeil Nielson and culturing with Lowenstein Jansen media. Cavitary upper lobe disease has good correlation with a sputum positive smear and hence is extremely infectious. Other differential diagnoses of cavitary pulmonary lesions include infections from Staphylococcus, Klebsiella, anaerobes, and non-infectious causes like squamous cell carcinoma of the lung, pulmonary infarcts, Wegener's granulomatosis, and rheumatoid nodules.

Vascular Graft Infections

The frequency of graft infections ranges from 1-5 . The majority of infections are thought to occur at the time of implantation. Staphylococci are the most common microorganism. Early infections are usually caused by S. aureus, whereas later infections are usually caused by coagulase-negative staphylococci. Rarely, Gram-negative bacilli may also cause infections of grafts. Graft infections, especially those involving coagulase-negative staphylococci, may not become evident for months to years. The majority of graft infections present as localized wound infections. Blood cultures are usually positive in less than 50 of patients. Graft thrombosis may suggest a graft infection. Graft infection may also manifest itself as an aortoenteric fistula with gastrointestinal bleeding. Needle aspiration of