A prospective evaluation of blood culture versus standard plate techniques for diagnosing peritonitis in continuous ambulatory peritoneal dialysis.

Peritonitis remains a major cause of morbidity in patients treated with continuous ambulatory peritoneal dialysis (CAPD). Culture-negative episodes of peritonitis occur at rates of up to 20%, and in part may reflect inadequate culturing techniques of peritoneal effluent. Through a large, prospective study, the improved sensitivity of a blood culture system, when compared with a standard plate technique (P = 0.001), for the detection of bacterial growth in 67 episodes of CAPD peritonitis is demonstrated. Improved recognition of infections caused by gram-positive organisms, primarily Staphylococcus epidermidis, was especially significant using the blood culture system (P = 0.0001). Because of improved sensitivity and a decreased time to organism identification, particularly with infections caused by S epidermidis, the most common cause of bacterial peritonitis in CAPD patients, we suggest that a blood culture system be the standard means of culturing peritoneal fluid in CAPD patients with peritonitis. The lysis-centrifugation system of culturing peritoneal fluid is also discussed in comparison with the blood culture system.