A total of 116 isolates from patients attending the
out-patient department at the All India Institute of Medical
Sciences, New Delhi and the New Delhi Tuberculosis Centre, New
Delhi, India were collected. They were analyzed for resistance to
drugs prescribed in the treatment for tuberculosis. The drug
resistance was initially determined by microbiological
techniques. The Bactec 460TB system was employed to determine the
type and level of resistance in each isolate. The isolates were
further characterized at molecular level. The multi-drug loci
corresponding to rpo β, gyr A, kat
G were studied for mutation(s) by the polymerase chain
reaction-single strand conformational polymorphism (PCR-SSCP)
technique. The SSCP positive samples were sequenced to
characterize the mutations in rpo β, and gyr A loci. While
previously reported mutations in the gyr A and rpo
β loci were found to be present,
several novel mutations were also scored in the rpo
β locus. Interestingly, analysis of the gyr A locus showed the
presence of point mutation(s) that could not be detected by
PCR-SSCP. Furthermore, rifampicin resistance was found to be an
important marker for checking multi-drug resistance (MDR) in
clinical isolates of Mycobacterium tuberculosis. This is
the first report on molecular genetic analysis of MDR
tuberculosis one from India, highlights the increasing incidence
of MDR in the Indian isolates of M. tuberculosis.
