PCR-Based Evaluation of Tuberculous Endometritis in Infertile Women of North India

BACKGROUND: Tuberculous endometritis is often a diagnostic dilemma for gynecologists in the evaluation of infertility. This study evaluated and compared different diagnostic methods in tuberculous endometritis. METHODS: 100 infertile women were investigated for tuberculous endometritis. The endometrial samples obtained by curettage were evaluated by Ziehl-Neelsen (ZN) staining of the smears for acid-fast bacilli (AFB), the samples were also cultured on Lowenstein-Jensen medium, and histopathological examination and nested PCR targeting ‘hupB’ gene (Rv 2986c in M. tuberculosis and Mb3010c in M. bovis) which can differentiate between M. tuberculosis and M. bovis were performed. Antibodies against 38-kDa and 16-kDa mycobacterial antigens were detected in serum using ELISA. Statistical analysis was done by online GraphPad Prism software, version 5.0. McNemar's test was applied and Kappa agreement coefficient was calculated for agreement between various methods. A p-value < 0.05 was considered significant. RESULTS: Among the 100 evaluated endometrial samples, one was AFB smear positive, none was positive by culture, four were positive by histopathology and 13 were positive by PCR. Of the 13 PCR-positive cases, 38.4% were positive for M. tuberculosis, 23.07% for M. bovis, and 38.4% showed co-infection with both species. 40% of the patients had raised IgG against M. tuberculosis 38-kDa antigen. McNemar's test was applied to PCR and the conventional methods of TB diagnosis (AFB, Culture and histopathology) and the p-value was < 0.001 (highly significant) for PCR. Detection by PCR showed a fair agreement with detection by Mantoux test and ELISA. CONCLUSION: In paucibacillary endometrial tuberculosis, the positive detection rate was found to be significantly higher for PCR compared to other methods. The ‘in-house’ nested PCR assay targeting the hupB gene and used in this study, can serve as a rapid diagnostic aid for tubercular endometritis. It can also differentiate between members of the Mycobacterium tuberculosis complex, namely M. tuberculosis and M. bovis.