Laboratory indices of clinical peritonitis: total leukocyte count, microscopy, and microbiologic culture of peritoneal dialysis effluent

Abstract

Total leukocyte count, microscopy, and conventional bacteriologic culture (10-ml sediment) of dialysis effluent were assessed for their ability to detect peritonitis in patients on peritoneal dialysis. A total of 73 patients were surveyed over a 17-month period. Laboratory findings included an examination of 1,774 dialysate samples and culture results from blood, wounds, indwelling catheters, and other specimens. Of 90 peritonitis events, 72 were culture positive. Gram-stained films were positive in no more than 14% of the dialysates collected during periods of clinical peritonitis. Factors which adversely affected the microscopic or cultural detection of microorganisms in effluent included the concentration of organisms in dialysate, antibiotic therapy, and growth medium used. Seeding of the peritoneum with organisms originating from other sites of infection or colonization was documented, although infrequent, yet bacteremia secondary to peritonitis was not seen. Because of the frequent isolation of microorganisms from dialysates in the absence of clinical peritonitis, culture-positive findings were a poor predictor of peritonitis without other evidence of infection. Detection of peritonitis by total leukocyte count (without a differential count) of dialysate specimens was adversely affected by the overlap in cell counts between dialysates collected either during or in the absence of peritonitis. This was attributed in part to nonspecific increases in dialysate cell count in the absence of peritonitis and was associated with intermittent dialysis and extraperitoneal infection.