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Tuberculosis (TB) is a major public-health problem in India, having the highest number of incident and multidrug-resistant (MDR) TB cases. The study was carried out to appraise the prevalence of first-line anti-TB drug resistance in Mycobacterium tuberculosis (MTB) and its patterns among different types of TB patients from different settings in a province of North India. Of 3,704 clinical specimens, 345 (9.3%) were culturepositive, and drug-susceptibility testing was carried out for 301 MTB strains. A high level of primary and acquired drug resistance of MTB was observed in the region studied, with weighted mean of 10.5% and 28.08%, 12.81% and 29.72%, 17.12% and 29.94%, 11.97% and 27.84%, and 10.74% and 23.54% for rifampicin, isoniazid, streptomycin, ethambutol-resistant and MDR cases respectively. Drug resistance was significantly higher in pulmonary (p=0.014) and acquired drug-resistant TB cases (p<0.001). Any drug resistance (p=0.002) and MDR TB were significantly (p=0.009) associated with HIV-seropositive cases. An urgent plan is needed to continuously monitor the transmission trends of drug-resistant strains, especially MDR-TB strains, in the region.

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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, hereinafter 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.

The global presence and rapid dissemination of Beijing genotype of Mycobacterium tuberculosis, makes it an important issue of public health. Its presence and association with multi-drug resistance has been shown in many settings. In present study we tried to find its prevalence and association with drug resistance in North India. One hundred and twenty four M. tuberculosis isolates were analyzed with spoligotyping, further drug susceptibility testing was done by 1% proportional method. Out of these, 11 (8.9%) M. tuberculosis isolates were identified as Beijing and 113 (91.1%) as non-Beijing genotypes. While looking at their drug susceptibility patterns, 6 (54.5%) & 22 (19.5%) were found to be multi drug resistant (MDR) among Beijing and non-Beijing isolates respectively. Our study concluded that the Beijing strains were not so common in north India and these strains do not fully associate with MDR.

In this study, we found that the majority of isolates were having multiple copy numbers of IS6110 element and showed a very diverse pattern. These results showed that the IS6110-RFLP analysis is still a promising genotyping method and has good discriminatory power to differentiate strains of MTB isolates in India.

Spoligotype analysis resulted in the grouping of a much larger number of isolates within apparently identical clusters compared with IS6110-RFLP typing, while IS6110-RFLP was not found to effectively distinguish between zero- and low-copy-number isolates. Therefore, we concluded that, in India, the use of both the techniques simultaneously for DNA fingerprinting of M. tuberculosis could be a better approach.