Introduction: Individuals with human immunodeficiency virus (HIV) infection have an increased likelihood of developing tuberculosis (TB). The primary objective of this study was to compare the diagnostic accuracy of microscopy, culture, and the Xpert Mycobacterium tuberculosis/Rifampicin (MTB/RIF) assay in the diagnosis of pulmonary TB in sputum samples of HIV-infected patients. The secondary objectives were to evaluate the sensitivity and specificity of these three methods along with a comparison of diagnostic approaches for detecting drug-resistant strains.
Material and methods: This prospective, laboratory-based study was done in the Microbiology Department of IGIMS, Patna. The study included sputum samples of 102 individuals who were HIV-positive and exhibited symptoms indicative of tuberculosis.
Results: Out of 102 individuals suspected of having tuberculosis, 18 tested positive for M. tuberculosis. Male individuals between the ages of 31 and 40 were more affected by both HIV and tuberculosis, and in most of these cases, their CD4 cell count was below 200 cells/µl. Among the 102 sputum samples collected, 18% (18 samples) were found to be positive using the Mycobacterium Growth Indicator Tube (MGIT) 960 liquid culture method. Two samples were contaminated, and 14.7% (15 cases) tested positive using the cartridge-based nucleic acid amplification test (CBNAAT) method. Additionally, 3.92% (four samples) were positive using the ZN staining method.
Conclusion: The study found that Xpert MTB/RIF outperformed other methods in identifying resistance to RIF, showed better agreement with gene sequencing results for RIF resistance, and had higher accuracy in detecting tuberculosis cases, including both smear-positive and smear-negative cases.
Keywords: culture; diagnosis; hiv-infected patients; pulmonary tuberculosis; xpert mtb/rif assay.
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