Evaluation of aerobic Bactec 6A non-resin- and 16A resin-containing media for the recovery of microorganisms causing peritonitis.

Recovery of microorganisms causing peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD) continues to be problematic. To date, there is no universally accepted protocol. We prospectively analyzed 430 peritoneal effluent specimens by three protocols: (a) 3 ml of effluent was centrifuged and the pellet plated onto blood and MacConkey agars and into thioglycolate broth (routine method), (b) 3 ml of each was inoculated at the bedside into Bactec 6A aerobic and 16A aerobic resin-containing media, and (c) 3 ml of each was inoculated in the laboratory into Bactec 6A and 16A media. Of the peritoneal effluent specimens, 104 (24%) had microorganisms recovered; 63 were positive by the routine method compared with 86 (P < .001) by bedside-inoculated 16A. Bedside-inoculated 16A (86) recovered more microorganisms than bedside-inoculated 6A (70) (P < .05). Laboratory-inoculated 16A (78) recovered more organisms than the routine method (63) (P < .05). Of 42 positive peritoneal effluent specimens delayed in transit > or = 1 day, 23 were positive by the routine method compared with 34 bedside inoculated 16A (P < .01) and 30 laboratory-inoculated 16A (P > .114). Bedside-inoculated 16A media is superior to the routine method for the recovery of microorganisms causing peritonitis in CAPD patients.