Assessing the significance of the β-actin gene in tuberculosis diagnosis: an analytical study utilizing anal fistula specimens

Fistula samples from suspected tuberculosis (TB) patients play a crucial role in diagnosing advanced extrapulmonary TB. This study examined 70 clinical specimens of anal fistulae suspected of Mycobacterium tuberculosis (MTB) infection using both conventional and molecular methods. The β-actin gene, a housekeeping gene, was assessed for TB detection while microbiological profiling identified acid-fast bacilli. Molecular profiling yielded positive results for both the IS6110 and β-actin genes in 14 samples, suggesting MTB infection. In 13 samples, only the β-actin gene was positive, indicating inflammation caused by other pathogens. Bayesian analysis was conducted to evaluate the diagnostic performance of both gene tests. The IS6110 gene test showed a sensitivity of 95% and specificity of 98% with a positive predictive value (PPV) of 0.819 and a negative predictive value (NPV) of 0.993. The β-actin gene test demonstrated a sensitivity of 90%, specificity of 99%, PPV of 0.966 and NPV of 0.984. Bayesian calculations indicated a posterior probability of 0.791 for TB in specimens positive for both genes. The findings emphasize the β-actin gene as a potential marker for TB infection. Its detection in TB-negative samples suggests the presence of alternative pathogenic microorganisms. This discovery could be crucial for confirming diagnoses, particularly when radiol