quantitative assessment of mycobacterial load through sputum smear grading and Truenat CFU/ml measurement

This study assessed mycobacterial load in sputum samples using smear microscopy grading and Truenat CFU/mL quantification, and evaluated the correlation between these diagnostic methods. Sputum specimens were collected from suspected pulmonary tuberculosis patients. Prepared sputum smears were stained using the Ziehl-Neelsen method, and the same sputum samples were tested using the Truenat platform. 85 (14.2%) tested positive for mycobacterium tuberculosis using Truenat. The infection rate was higher in males (61.2%), with the highest prevalence observed in the 21–30 age group. Of the 85 Truenat-positive cases, 66 (77.6%) were also positive on smear microscopy. Notably, adult males were more likely to present with high-grade smears (3+), indicating greater infectivity. The correlation between smear grade and Truenat CFU/mL was statistically significant (Chi-square = 4.2736, p = 0.0387), meeting the threshold for significance at p < 0.05. Bacterial loads ranged from 2.7 × 10¹ to 5.6 × 10⁷ CFU/mL. A high bacterial load (≥10⁶ CFU/mL) was observed in over 21% of patients, reflecting advanced disease stages. However, Truenat demonstrated superior diagnostic performance, achieving 100% sensitivity and specificity, compared to smear microscopy, which showed 61.67% sensitivity and 76% specificity.