Clinical and microbiological evaluation of four culture methods for the diagnosis of peritonitis in patients on continuous ambulatory peritoneal dialysis

Abstract

A prospective study was performed to evaluate four culture methods for the diagnosis of bacterial peritonitis in patients on continuous ambulatory peritoneal dialysis. Peritonitis was present in 44 of 85 patient admissions (52%). The overall sensitivity of the culture methods in detecting peritonitis was 66%. The sensitivities of the individual methods were as follows: bag culture method, 61%; blood culture broth method, 51%; filter method, 54%; and plate method, 39%. Our broad definition of peritonitis resulted in lower sensitivities. A combination of the bag and blood culture broth methods detected all positive cultures.

Microbiological aspects of peritonitis associated with continuous ambulatory peritoneal dialysis.

“…In one series, 20 to 400 ml of filtered dialysate gave results similar to 10 ml of plated and enriched pellets (90). Likewise, 100 ml of dialysate filtered through a 0.45-,u.m-pore-size filter gave results identical to those obtained with 10 ml of enriched specimen (115) but was superior to results with plated pellets from 5 to 10 ml of centrifuged dialysate (31). Millipore filtration of 300 ml of dialysate was equal in qualitative yield to direct plating of 0.5 ml (82), although the number of colonies was higher.…”

“…In one study of 3,876 daily surveillance cultures of dialysates, 183 positive cultures were detected, but only 30 of them were associated with peritonitis (as defined by cloudy fluid plus abdominal pain); the other 153 did not indicate present or future infection (152). Other authors (29,31,89,116) also found growth in up to 10% of effluents from nonperitonitis patients. In such cultures, coagulase-negative staphylococci, Propionibacterium, Acinetobacter, and Bacillus species (130,152), and (rarely) agents known to cause more severe forms of CAPD peritonitis (116,152) were found.…”

“…Cultures of fluids from patients with CAPD peritonitis have been reported as negative in 4 to 48% of all episodes (31,73,89,123,124,139,148). Such results are significantly more frequent when WBC counts are below 500/mm3 (36,90).…”

“…Enrichment of large dialysate volumes has yielded high sensitivities compared with other methods but is impractical for routine use (because of handling and preparation of special concentrated broths for mixing) and may yield falsepositives. Dialysate volumes of 1,000 (29,31) and 500 (125) ml have been cultured. Sensitivity (compared with clinical signs and symptoms) was limited by the presence of antibiotics and has ranged from 100% (29) to 88% (125) to 61% (31).…”

“…Dialysate volumes of 1,000 (29,31) and 500 (125) ml have been cultured. Sensitivity (compared with clinical signs and symptoms) was limited by the presence of antibiotics and has ranged from 100% (29) to 88% (125) to 61% (31). We found that 1,000 ml of sample gave the same results as 50 ml (sensitivity, 70%) (52).…”