Devendra Singh Chauhan

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Treatment of multidrug-resistant tuberculosis has become one of the major problems in public health. Understanding the molecular mechanisms of drug resistance has been central to tuberculosis research in recent times. DNA microarray technology provides the platform to study the genomic variations related to these mechanisms on a comprehensive level. To(More)
Although India has the highest prevalence of tuberculosis (TB) worldwide, the genetic diversity of Mycobacterium tuberculosis in India is largely unknown. A collection of 91 isolates originating from 12 different regions spread across the country were analyzed by genotyping using 21 loci with variable-number tandem repeats (VNTRs), by spoligotyping, by(More)
BACKGROUND & OBJECTIVES Drug efflux pumps have been contributing factor(s) in the development of multidrug resistance in various clinically relevant bacteria. During efflux pump gene expression studies on mycobacteria, we have found a previously uncharacterized open reading frame (ORF) Rv2459 to be overexpressed in drug stressed conditions. The objective of(More)
BACKGROUND & OBJECTIVE Infection due to Mycobacterium bovis typically occurs in cattle and animals transmit infection to each other. The choice of appropriate clinical specimen is very important for isolation of M. bovis and M. tuberculosis from cattle. The present study reports the isolation of M. tuberculosis and M. bovis from different types of specimens(More)
Mycobacterium tuberculosis and M. bovis infect animals and humans. Their epidemiology in developed and developing countries differs, owing to differences in the implementation of preventive measures (World Health Organization, 1999). Identification and differentiation of these closely related mycobacterial species would help to determine the source,(More)
For isolation of environmental mycobacteria, a decontamination procedure has been standardized by which treatment with 3% sodium dodecyl sulfate plus 4% NaOH (15 and 30 min for rapid and slow growers, respectively) is followed by incubation with 2% cetrimide (5 and 15 min for fast- and slow-growing mycobacteria, respectively); this procedure was found to(More)
Mycobacterium w (Mw), is a cultivable, non-pathogenic mycobacterium and has been tried extensively as an immunomodulator in leprosy. This has been found to be safe and has shown beneficial immunoprophylactic effect in population based, double blind placebo controlled trials in North India. These effects were also observed in the vaccine trials in South(More)
Molecular typing of Mycobacterium tuberculosis isolates has greatly facilitated the understanding of epidemiology of tuberculosis (TB). This study was done to characterize prevalent genotypes of M. tuberculosis on a collection of 97 isolates based on spoligotyping and mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR)(More)
Pyrazinamide (PZA) is an important first-line antituberculosis drug because of its sterilizing activity against semidormant tubercle bacilli. In spite of its very high in vivo activity, its in vitro activity is not apparent unless an acidic environment is available, which makes PZA susceptibility testing difficult by conventional methods. The present study(More)
PCR has emerged as a powerful technique for detection of various pathogens including Mycobacterium tuberculosis. In present study, eighty one samples of lymph node biopsies from clinically suspected cases of tuberculous lymphadenitis were examined for AFB, culture on Löwenstein Jensen medium and simultaneous use of two PCRs targeting IS6110 and MPB64.(More)