Primary and acquired drug resistance patterns of Mycobacterium tuberculosis isolates in India: a multicenter study

ABSTRACT

Tuberculosis is the most prevalent infection worldwide. The emergence of drug-resistant Mycobacterium tuberculosis [M. tuberculosis] isolates emphasizes that it is necessary to monitor drug resistance of the organism against anti-tubercular drugs. We analyzed 327 M. tuberculosis isolates from patients who were cared for at three different health care centers, herein after known as study areas [SAs], in North India. Of the 327 total M. tuberculosis isolates, 255 were from a tertiary health care center [Varanasi, Uttar Pradesh [SA-1]], 48 were from a District tuberculosis center [Sawai Madhopur, Rajasthan [SA-2]], and 24 were from a different District tuberculosis center [Buxar, Bihar [SA-3]]. Drug susceptibility testing against first-line antibiotics [viz. isoniazid, rifampicin, streptomycin, and ethambutol] was conducted for all the isolates using 1% proportional method. We found that the rates of acquired resistance were consistently higher than the rates of initial drug resistance. In new, untreated cases, a higher degree of MDR-TB was observed at SA-1 [13.3%] and SA-3 [25.0%], whereas it was observed in only 7.1% of the isolates at SA-2. In previously treated patients, MDR cases were found in 35.7% of the isolates from SA-1, 66.6% of the isolates from SA-2, and 43.8% of the isolates from SA-3. Resistance to a single drug was found at a much lower rate, ranging from 0.0 to 6.3% in new cases as well as previously treated cases. In conclusion, the primary resistance of M. tuberculosis is low, but acquired drug resistance is slightly higher in North India