The laboratory diagnosis of peritonitis during continuous ambulatory peritoneal dialysis.

In 24 episodes of continuous ambulatory peritoneal dialysis associated peritonitis occurring in 21 patients, all dialysis fluids were cloudy and contained at least 100 cells mm-3, mostly polymorphs. Gram-positive cocci were seen in centrifuge deposits from only nine of the fluids, but enrichment of 5 ml in liquoid and glucose broth yielded bacteria for all episodes, namely Staphylococcus epidermidis (seven episodes), Staph. aureus (six), Streptococcus mitior (one), Moraxella spp (four), Acinetobacter spp (three), Enterobacteria (two) and Pseudomonas testosteroni (one). Comparison of washed with unwashed centrifuge deposits gave positive cultures in 11 and 10 fluids respectively; pre-treatment with triton X increased this yield to 19 and 21 positives, respectively. Storage of specimens for 4-12 h at 4 degrees C did not decrease the 100% positive-culture rate. All isolates were sensitive to either gentamicin or vancomycin. Of the 24 dialysis bags from 24 symptomless CAPD patients, none contained more than 60 cells mm-3 and bacteria were not detected by microscopy, culture of the centrifuge deposits, or by enrichment in liquoid or glucose broths.