Author: Rashmi Ratnam, Dr Parul Jain, Dr Amita Jain.

Background: As per WHO Guidelines and NTEP India, Nucleic Acid Amplification Test (NAAT) is recommended as upfront test for patients with presumptive tuberculosis, mostly the drug regimen is initiated on this ground. Equally important drugs Isoniazid and fluoroquinolones are remain unconsidered sometimes.

Objective: To estimate frequency of Isoniazid and fluoroquinolones resistance among Rifampicin sensitive strains of M. tuberculosis.

Methods: NAAT positive TB patients samples from 24 district of Uttar Pradesh, India were tested for first line/second line - line probe assay (LPA) at IRL.

Results: Total 13188 NAAT tested samples were subjected for FL-LPA; 9722 (74%) were sensitive, 3455 (26.32%) were resistant and 110 (0.8%) were indeterminate for rifampicin (Rif). In 9722 Rif sensitive strains, isoniazid resistant strains were 814 (8.5%), among these high level katG gene mutation occurred in 613 (75%), low level InhA gene mutation occurred in 182 (22.35%) and both KatG and InhA gene mutation occurred in 19 (2.33%) M. tuberculosis strains. In 814 isoniazid resistant M. tuberculosis strains, fluroquinolones resistance were found in 106 (13.02%), from these 60 (56.6%) were high level and 46 (44.2%) were low level FQ resistant .

Conclusion: High percentage of rifampicin sensitive patients were found to have high and/or low level of resistance for isoniazid (8.5%) and fluoroquinolones (13.02%). We recommend that the treatment regimen of a patient should be designed based on universal DST patterns for eligible drugs not only based on NAAT results.