USE OF PROTOTYPE AUTOMATED BLOOD CULTURE SYSTEM AND GAS-LIQUID-CHROMATOGRAPHY FOR THE ANALYSIS OF CONTINUOUS AMBULATORY PERITONEAL-DIALYSISASSOCIATED INFECTION

Aims-(1) To compare the recovery of organisms from continuous ambulato ry peritoneal dialysis (CAPD) effluent fluid obtained from patients wi th clinical evidence of peritonitis, with an automated system (AS) and the Septichek blood culture system; (2) to evaluate the times to dete ction of organisms with the two systems; (3) to identify anaerobes fro m CAPD samples by extended anaerobic culture and gas-liquid chromatogr aphy (GLC). Methods-168 CAPD effluent fluid samples were studied, repr esenting 157 episodes of peritonitis in 97 patients. CAPD samples were inoculated into two AS bottles-one anaerobic, one aerobic-and a Septi chek bottle; samples were also examined for cell count, Gram stain, an d direct culture. Culture bottles were then subcultured onto various m edia, and any organisms isolated were identified. After routine cultur e, GLC was performed on culture fluid in the anaerobic AS and Septiche k bottles. When volatile fatty acids were detected, the broths were cu ltured anaerobically on specialised medium for a further five days. Re sults-147 organisms were isolated from the 168 samples: 96 (57%) yield ed growth of significant organisms by direct culture, as compared to 1 29 (76.8%) by both AS and Septichek. There was no significant differen ce in isolation rates between AS and Septichek, but time to detection was more rapid with the AS system (p < 0.002). GLC showed volatile fat ty acid in 15 specimens; of these, 14 subsequently grew anaerobic orga nisms. Conclusions-AS was comparable to Septichek for numbers of isola tions. Speed to detection was faster with the AS, which may be an adva ntage in management of patients with CAPD peritonitis. GLC showed anae robes in several cases which would not have been detected without prol onged anaerobic culture; thus anaerobic cultures are recommended for p atients who are unresponsive to antimicrobials or who have evidence of bowel perforation.