Profile of drug-resistant-conferring mutations among new and previously treated pulmonary tuberculosis cases from Aligarh region of Northern India.

Background: The prevalence of multidrug-resistant-tuberculosis (MDR-TB) among new and previously treated cases is increasing worldwide as well as in India. Rapid detection of MDR-TB allows the establishment of an effective treatment regimen; minimizes the risk of further resistance, and limits the spread of drug-resistant strains. Early diagnosis of MDR-TB is the need of the hour in high-TB burden countries like India, and GenotypeMTBDRplus is quite sensitive and specific in determining the molecular resistance in drugs such as rifampicin and isoniazid.

Methods: The present study was done for molecular detection of rifampicin and isoniazid resistance and resistance patterns among MDR-TB suspects and comparison of resistance patterns among new and previously treated cases by GenoType MTBDRplus Line Probe Assay. A total of 1268 sputum samples of MDR-TB suspects were subjected to fluorescent microscopy. Fluorescent microscopy positive samples were subjected to GenoType MTBDRplus (HAIN Lifescience) assay.

Results: MDR-TB was detected 11.02%, 20.03% in new and previously treated cases. Among MDR-TB patients S531 L was the most common mutation detected in rpoB gene; 71.43% in new, and 72.17% in previously treated cases. S315T1 was the most common mutation noted in katG gene; 100% in new and 81.74% in previously treated. While in hA gene, it was C15T (7.8%) among previously treated cases.

Conclusion: MDR-TB has high prevalence in the western part of Uttar Pradesh, India. Previously treated cases have even more high rate of MDR-TB than new TB cases. The most dominant gene mutations associated with resistance to INH and RIF were observed in codon 315 of the katG gene and codon 531 of the rpoB gene. While comparing the mutation patterns by Genotype MTBDRplus assay, previously treated cases showed more diversity of mutations and had greater number of unknown mutations.