Rapid diagnosis of Mycobacterium tuberculous peritonitis in two continuous ambulatory peritoneal dialysis patients, using DNA amplification by polymerase chain reaction

Tuberculous peritonitis is not an uncommon cause of continuous ambulatory peritoneal dialysis (CAPD) peritonitis in endemic countries. The diagnosis is usually delayed because peritoneal fluid smears for acid-fast bacilli (AFB) are insensitive, and cultures for Mycobacterium tuberculosis require weeks. The present paper reports two cases of tuberculous CAPD peritonitis that were rapidly diagnosed using gene amplification for M. tuberculosis DNA complex by polymerase chain reaction with the commercial Amplicor M. tuberculosis nucleic acid amplification test (Roche Diagnostic Systems, Branchburg, NJ, U.S.A.). A 18-year-old man and a 50-year-old man, both on CAPD, developed culture-negative peritonitis. Empirical therapy with intraperitoneal vancomycin and gentamicin failed. Peritoneal fluid AFB smears were negative. In both patients, M. tuberculosis DNA complex was detected by nucleic acid amplification using the Amplicor test. Anti-tuberculosis treatment was unsuccessful and their catheters were removed. Six weeks later, their peritoneal fluid cultures isolated M. tuberculosis. The use of molecular techniques to assist in the diagnosis of pulmonary tuberculosis is well accepted. Little information exists regarding the use of molecular techniques in the diagnosis of tuberculous CAPD peritonitis. The diagnosis of tuberculous peritonitis in CAPD patients is frequently delayed and may cause increased morbidity and mortality. Molecular diagnosis of tuberculous peritonitis using nucleic acid amplification tests may allow more rapid diagnosis. Further studies are required to determine the sensitivity and specificity of the technique in CAPD patients with tuberculous peritonitis.