Pseudomonas Stenotrophomonas Burkholderia

■ Pseudomonads are Gram-negative, aerobic, rod-shaped bacteria with widespread occurrence in nature, especially in damp biotopes. The most important species from a medical point of view is Pseudomonas aeruginosa. Free O2 is required as a terminal electron acceptor to grow the organism in cultures. The pathogenesis of Pseudomonas infections is complex. The organism can use its attachment pili to adhere to host cells. The relevant virulence factors are: exotoxin A, exoenzyme S, cytotoxin, various metal proteases, and two types of phospholipase C. Of course, the lipopolysaccharide of the outer membrane also plays an important role in the pathogenesis. Pseudomonas infections occur only in patients with weakened immune defense systems,

Pseudomonas, Stenotrophomonas, Burkholderia 309

notably pneumonias in cystic fibrosis, colonization of burn wounds, endocarditis in drug addicts, postoperative wound infection, urinary tract infection, sepsis. P. aeruginosa frequently contributes to nosocomial infections. Diagnosis requires identification of the pathogen in cultures. Multiple resistance to anti-infective agents presents a therapeutic problem.

Numerous other Pseudomonas species and the species of the genera Burkholderia and Stenotrophomonas are occasionally found in pathogenic roles in immunosuppressed patients. B. mallei causes malleus (glanders) and B. pseu-domallei causes melioidosis. ■

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Essentials of Human Physiology

Essentials of Human Physiology

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