Four-year analysis of microbial aetiology and antimicrobial sensitivity patterns of peritoneal-dialysis related peritonitis in a tertiary care facility.

Peritonitis related to peritoneal dialysis increases morbidity and mortality and is the main reason for switching to haemodialysis. In this study, we analysed the dialysate of 164 peritoneal dialysis patients that was sent to our laboratory between January 2005 and August 2009. There were 196 peritonitis episodes identified in 78 patients. For all episodes, microbial aetiologies and in-vitro antimicrobial sensitivities were determined in addition to parameters such as the leukocyte count (WBC) and the result of the Gram stain. Results in children were analysed separately because of previously described differences in aetiology. In both groups, Gram positives were most commonly isolated, followed by Gram negatives and fungi or yeasts. In children, the proportion of coagulase-negative staphylococci compared to S. aureus is smaller than in adults. Gram stain showed predominant morphotypes concordant with culture results in 28% of episodes. A significant difference in WBC count was found between culture-positive (mean=3117 x 10(9)/L) and culture-negative (mean=981 x 10(9)/L) episodes in adults (p=0.001). The WBC count in episodes caused exclusively by CNS (mean=1502x10(9)/L) was also on average significantly lower (p=0.001) compared to all culture positive episodes. Resistance to methicillin was registered in 33% of cultures, positive for staphylococci. All Gram-positives were sensitive to vancomycin. Coverage of Gram-negatives by ceftazidim and quinolones was excellent (89%). Based on local sensitivity data and known characteristics of antimicrobials, a first-line empirical combination of intraperitoneal vancomycin with orally administered ciprofloxacin seems indicated in our population. Pathogens of positive aerobic cultures were sensitive in-vitro to their combined antimicrobial effect in 90% of cases.