DIRECT-DETECTION OF MYCOBACTERIUM-TUBERCULOSIS USING POLYMERASE CHAIN-REACTION ASSAY AMONG PATIENTS WITH HEPATIC GRANULOMA

Background: In liver tuberculosis, demonstration of acid bacilli by co nventional methods remains futile, Since the definitive diagnosis of l iver tuberculosis is based on the histologic evidence of granulomatous process with caseation necrosis, seen in only a third of cases, the d iagnosis is made retrospectively by response to empirical anti-tubercu lous drug therapy. Aims: Our objective is to establish a polymerase ch ain reaction assay for detection of Mycobacterium tuberculosis affecti ng the liver using the paraffin-embedded liver biopsy specimens obtain ed from patients with hepatic granulomas. Methods: As positive control , patients having either ''definitve'' (n=8) or ''presumptive'' (n=9) tuberculosis on the basis of clinical, microbiological, histologic dat a and their positive response to empirical treatment of anti-tuberculo us drugs were used, Patients with hepatic granulomas secondary to schi stosomiasis (n=6), sarcoidosis (n=2) and other liver diseases (n=10) w ere used as negative control. Results: Of those patients who were diag nosed as having ''definitive'' and ''presumptive'' liver tuberculosis, positivity by one-step polymerase chain reaction was 100% and 44%, re spectively, Using the nested polymerase chain reaction, positivity inc reased to 78% with ''presumptive'' liver tuberculosis, In contrast, th e polymerase chain reaction assays were negative among all patients wi th hepatic granuloma due to non-tuberculous-in-origin and other liver diseases. Conclusions: The overall positivity of this polymerase chain reaction assay (88%) compares favorably with that of other convention al methods (12%), Thus, this polymerase chain reaction assay may be a reliable diagnostic tool for liver tuberculosis in a patient populatio n in which the prevalence of diseases associated with hepatic granulom a is common.