title: Molecular characterisation of drug resistance in Mycobacterium tuberculosis isolates from North India.
abstract: METHODS
  A tertiary care hospital in North India.
  
  
  OBJECTIVE
  To analyse the frequency of mutations associated with resistance to rifampicin (RMP), isoniazid (INH) and streptomycin (SM) in Mycobacterium tuberculosis.
  
  
  METHODS
  M. tuberculosis isolates from 171 pulmonary  tuberculosis (TB) patients (newly diagnosed 102, 59.6%; retreated 69, 40.3%) were analysed. Drug susceptibility testing was performed using the proportion method and resistant isolates were characterised using the polymerase chain reaction, followed by restriction fragment length polymorphism  and/or DNA sequencing, to screen for mutations in rpoB, katG, mabA-inhA and rpsL.
  
  
  RESULTS
  Of the 171 isolates, 16.9% (29/171) were multidrug-resistant. Of the 102 newly diagnosed and 69 retreated cases, respectively 5.9% (6/102) and 33.3% (23/69) were  multidrug-resistant. rpoB mutations were found in 100% (31/31) of the RMP-resistant isolates, the most common being S531L in 74.2% (23/31); katG315 mutations were found in 79.6% (35/44) of the INH-resistant isolates; however, no mabA-inhA (-15) mutation  was found; rpsL mutations were found in 48.9% (24/49) of the SM-resistant isolates, and codon 43 mutation were found in 42.5% (21/49).
  
  
  CONCLUSIONS
  This study characterises drug resistance-associated mutations in M. tuberculosis, information that could be used for the rapid  screening of drug-resistant TB.
authors: Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors: R
authors: R
authors: Yadav
authors: S
authors: S
authors: Sethi
authors: S K
authors: SK
authors: Dhatwalia
authors: D
authors: D
authors: Gupta
authors: A
authors: A
authors: Mewara
authors: M
authors: M
authors: Sharma
mesh_terms: D000293:Adolescent; D000995:Antitubercular Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D008297:Male; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D004269:DNA, Bacterial