Detection of <i>Mycobacterium tuberculosis</i> on stool specimens by PCR among patients with pulmonary tuberculosis.

Kesarwani, Vasudha; Singh, N P; Kashyap, Bineeta; Kumar, Amit · J Family Med Prim Care · 2022

case_control · Level III

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Abstract

To detect <i>Mycobacterium tuberculosis</i> on stool specimens by polymerase chain reaction (PCR) among patients with pulmonary tuberculosis. Detection of <i>M. tuberculosis</i> complex in sputum forms the basis of diagnosis of pulmonary tuberculosis. However, some patients tend to swallow sputum and some are unable to produce sputum. Based on the survival of <i>M. tuberculosis</i> in the gastric fluid, swallowed organisms may be detectable in stool samples. The study was carried out on 30 cases each in four groups: sputum smear-positive and sputum smear-negative adults, pediatric patients suspected of pulmonary tuberculosis along with healthy controls. The samples were processed for direct microscopy for acid-fast bacilli (AFB) and <i>M. tuberculosis</i> culture. Stool PCR was done on all 120 samples. AFB was demonstrated in 42 and cultured in 39 out of 240 samples. PCR-targeting IS6110 gene showed positive results in 24 (20%) out of 120 stool samples. PCR in stool showed the highest positivity in sputum smear-positive samples followed by gastric aspirates and sputum smear-negative samples. Stool PCR is a potentially useful diagnostic method for pulmonary tuberculosis.