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Background & objectives: One-fifth of the world’s new tuberculosis (TB) cases and two-thirds of cases in the South East Asian region occur in India. Molecular typing of Mycobacterium tuberculosis isolates has greatly facilitated to understand the transmission of TB. This study was aimed to investigate the molecular epidemiology of M. tuberculosis genotypes in Varanasi, north India, and their association with clinical presentation among patients with pulmonary TB. Methods: M. tuberculosis isolates from 104 TB patients attending a tertiary referral hospital of north India were screened for susceptibility to isoniazid (INH), rifampicin (RIF), ethambutol (EMB) and streptomycin (STR) by proportion method and multiplex-allele-specific-polymerase chain reaction (MAS-PCR). These were genotyped by spoligotyping. The spoligotype patterns were compared with those in the international SITVIT2 spoligotyping database. Results: Eighty three of 104 isolates were distributed in 38 SITs, of which SIT3366 was newly created within the present study. The mass of ongoing transmission with MDR-TB isolates in Varanasi, northern India, was linked to Beijing genotype followed by the CAS1_Delhi lineage. HIV-seropositive patients had a significantly higher proportion of clustered isolates than HIV-seronegative patients and compared with the wild type(wt) isolates, the isolates with katG315Thr mutation were considerably more likely to be clustered. Interpretation & conclusions: This study gives an insight into the M. tuberculosis genetic biodiversity in Varanasi, north India, the predominant spoligotypes and their impact on disease transmission. In this region of north India, TB is caused by a wide diversity of spoligotypes with predominance of four genotype lineages: Beijing, CAS, EAI and T. The Beijing genotype was the most frequent single spoligotype and strongly associated with multi drug resistant (MDR)-TB isolates. These findings may have important implications for control and prevention of TB in north India.
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Objective To explore the distribution and characteristics on genotype of Mycobacterium tuberculosis and the relationship between Beijing genotype and drug-resistant phenotypes in Tianjin city. Methods 656 clinical strains were collected from Tianjin Center for Tuberculosis Control and ten other Tuberculosis Institute in Tianjin from January 2008 to June 2009.Information regarding administration, clinical as well as laboratory findings of patients were collected.Proportion method was adopted to detect the susceptibility on four anti-tuberculosis drugs, namely streptomycin (SM), isoniazid (INH), rifampicin (RFP) and ehambutol (EMB). Both Beijing and non-Beijing genotypes were differentiated by multiplex PCR. The relationship between Beijing genotype and drug-resistant phenotypes was analyzed. Results In this study, the overall resistance rate of MTB was 26.98%, with multidrug-resistant rate was 6.25%. Among 656 MTB strains, 600isolates (91.46% ) belonged to Beijing genotype. There was significant difference between Beijing and non-Beijing genotype (x2=4.26, P=0.039) among the Tianjin household registered population.Concerning the drug resistance, there was no significant difference between the two groups.Conclusion Beijing genotype strains were the predominant one in Tianjin. The proportion of people infected with the Beijing genotype strains in Tianjin household registration of patients was significantly higher than the proportion of patients in the floating population in the same region.Results from the statistical analysis did not reveal any statistically significant association between Beijing genotype and drug resistance.