With Continuous Ambulatory Peritoneal Dialysis

2.1. Clinical Relevance and Microbiology

The rate of peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD) is decreasing, down from 2.8 to 0.8 episodes per year (4). S. aureus and coagulase-negative staphylococci account for 50-80% of CAPD peritonitis cases. Streptococci cause approx 10%, of these infections and Gram-negative bacilli are isolated in another 20% of cases. Infections with mycobacteria and fungi are rare but cause serious complications. Sources of peritonitis associated with CAPD include contamination of the catheter during implantation, manipulation of the dialysate tubing, the dialysate fluid itself, and possible bowel perforation. Most often, the peritoneum is infected by organisms that invade along the catheter tract. Lack of proper sterile technique is a major risk factor.

2.2. Clinical Manifestations, Diagnostic Tests, and Treatment

The clinical diagnosis of peritonitis associated with CAPD is suggested by abdominal pain (78%), a cloudy effluent (98%), vomiting (25%), nausea, fever (50%), and an elevated peripheral white blood cell count with a left shift. The Gram stain is positive in only 10-40% of cases. There should be more than 100 polymorphonuclear cells per mm3 in the examined fluid. If blood culture bottles are used to culture the dialysate fluid, then the yield of positive cultures is increased (80%). Bacteremia is unusual. An ultrasonogram may reveal pericatheter fluid collections as well.

The Advisory Committee on Peritonitis Management of the International Society for Peritoneal Dialysis has published guidelines for treatment of these infections on the Internet. These are available at http://www.ispd.org/guidelines.php3. See Tables 1 and 2 for specific therapy. Cefazolin and tobramycin are regarded as appropriate initial therapy (4,5). Because of the potential for emergence of vancomycin resistance, van-

Table 1

Treatment of Peritonitis Associated with Chronic Ambulatory Peritoneal Dialysis

Initial empiric therapy

Cefazolin—500 mg/L loading dose, maintenance 125 mg/L ip and tobramycin or gentamicin or netilmicin—0.6 mg/kg B.W. ip once daily or amikacin 2.0 mg/kg B.W. ip once daily

Because of the emergence of vancomycin-resistant organisms, vancomycin is reserved for the following: methicillin-resistant S. aureus, p-lactam-resistant organisms or serious peritonitis in patients allergic to other antibiotics

Enterococci

Stop cephalosporin, continue aminoglycosides, add ampicillin 125 mg/L and continue therapy for 14 d.

S. aureus

Discontinue aminoglycoside, continue cephalosporin, and consider rifampin 600 mg/d p.o.; continue therapy for 21 d, and reevaluate. If no improvement by 96 h, consider other antibiotics or catheter removal

Coagulase-negative staphylococci

Discontinue aminoglycoside and continue cephalosporin for 14 d if susceptible.

Single Gram-negative organism (other than P. aeruginosa)

Adjust antibiotics according to sensitivity patterns (usually sensitive to an aminoglycoside).

P. aeruginosa

Tobramycin or gentamicin or netilmicin - 0.6 mg/kg B.W. ip once daily or amikacin 2.0 mg/kg B.W. ip once daily for 21-28 d with another anti-Pseudomonal agent.

Multiple organisms

Consider surgical intervention

Add metronidazole 500 mg every 8 h iv po, or rectally; continue therapy up to 21 d B.W., body weight; ip, intraperitoneal; po, oral; iv, intravenous.

Table 2

Fungal and Tuberculous Peritonitis

Fungal

Fluconazole 150 mg/ip every second d and flucytosine (loading dose 2000 mg po, maintenance 1000 mg po) or amphotericin B 25 mg/d iv and flucytosine as above. Note: duration of therapy 4-6 wk or longer

Tuberculous

Early diagnosis and treatment is crucial. Catheter removal appears to be mandatory. Mycobacterial DNA in peritoneal fluid, using polymerase chain reaction appears to offer the fastest diagnosis, but culture and smear should be done as well. Laparoscopy and biopsy may be necessary for diagnosis. Triple drug therapy (isoniazid, rifampin, and pyrazinamide) is the mainstay of therapy, but local drug sensitivities should be considered.

ip, intraperitoneal; po, oral; iv, intravenous.

comycin is reserved for methicillin-resistant S. aureus, |3-lactam-resistant organisms or serious peritonitis in patients allergic to other antibiotics. If the patient is culture negative after 2-3 d and clinically improved, the aminoglycoside may be discontinued and the cephalosporin continued for 14 d. Intraperitoneal antibiotics are as effective as systemic in most cases.

2.3. Prevention

In patients with peritoneal catheters, prophylaxis for invasive procedures such as dentistry and colonoscopy could follow the American Heart Association Guidelines for Prevention of Endocarditis. However, no control studies have ever been performed. Many patients with Tenchoff catheters are carriers of S. aureus. Intranasal mupirocin and oral rifampin may reduce the frequency of exit site infections due to S. aureus.

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