Shilpa1, Shobha D. Nadagir2, Jnaneshwara K.B.3,
Asha B. Patil3, Aaftab G. Pendari3 and Uma Chikkaraddi3

1Department of Microbiology, KIMS Hubballi, Karnataka – 580 022, India.
2Department of Microbiology, Navodaya Medical College, Raichur, Karnataka, India.
3Department of Microbiology, KIMS Hubballi, Karnataka – 580 022, India.


Tuberculosis(TB) remains the most common opportunistic infection among people living with HIV (PLHIV) and diagnosing it becomes a challenging task as sputum microscopy is negative in more than half of the patients. Delayed treatment for TB in PLHIV is associated with increased mortality. Cartridge Based Nucleic Acid Amplification Test (CBNAAT) is a recently introduced Polymerase chain reaction based method for detection of Mycobacterium tuberculosis, which also detects Rifampicin resistance as it targets the rpoB gene of mycobacteria. To determine the prevalence of Rifampicin resistance in HIV seropositive patients with suspected pulmonary tuberculosis in a tertiary care hospital by using CBNAAT. HIV seropositive patients with clinically suspected tuberculosis were included in the study. Two sputum samples from each patient were collected and subjected to sputum microscopy by LED-fluorescent Microscope. Detection of mycobacteria and Rifampicin resistance was carried out by CBNAAT on Gene Xpert MTB/RIF. Out of the total 576 sputum, 74 (12.84%) patients were positive by sputum microscopy for acid fast bacilli and 137 (23.78%) were positive by CBNAAT. Rifampicin resistance was detected in 12 (8.75%) cases. CBNAAT helped in increased case detection in lesser time as compared to sputum microscopy. It also detects Rifampicin resistance with high specificity and can be used for screening for MDR-TB for the purpose of starting category IV anti-tubercular therapy (ATT) early.

Keywords: Tuberculosis, CBNAAT, Rifampicin resistance, HIV sero-positive.