title: A study on pre-XDR & XDR tuberculosis & their prevalent genotypes in clinical isolates of Mycobacterium tuberculosis in north India.
abstract: OBJECTIVE
  Pre-extensively drug resistant (pre-XDR) and extensively drug resistant tuberculosis (XDR-TB) have been areas of growing concern, and are posing threat to global efforts of TB control. The present study was planned to study the presence of pre-XDR and XDR Mycobacterium tuberculosis and their genotypes in clinical isolates obtained from previously treated cases of pulmonary TB.
  
  
  METHODS
  A total of 219 isolates obtained from previously treated cases of pulmonary TB were subjected to first-line (streptomycin, isoniazid, rifampicin and ethambutol) and second-line (ofloxacin, kanamycin, capreomycin and amikacin) drug susceptibility testing on solid Lowenstein-Jensen medium by proportion method. Genotyping was done for pre-XDR and XDR-TB isolates using 12 loci Mycobacterial Interspersed Repetitive Units-Variable Number Tandem Repeats (MIRU-VNTR).
  
  
  RESULTS
  Multi-drug resistance was observed in 39.7 per cent (87/219) isolates. pre-XDR and XDR M. tuberculosis isolates amongst 87 multi-drug resistant (MDR) TB isolates were 43 (49.4%) and 10 (11.4%), respectively. Two most dominant genotypes among pre-XDR and XDR M. tuberculosis isolates were Beijing and Delhi/CAS types.
  
  
  CONCLUSIONS
  Resistance to second-line anti-tubercular drugs should be routinely assessed in areas endemic for TB. Similar genotype patterns were seen in pre-XDR and XDR-TB isolates. Beijing and Delhi/CAS were predominant genotypes.
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, India.
authors.forename: Parul
authors.initials: P
authors.lastname: Singhal
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, India.
authors.forename: Pratima
authors.initials: P
authors.lastname: Dixit
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, India.
authors.forename: Pooja
authors.initials: P
authors.lastname: Singh
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, India.
authors.forename: Indu
authors.initials: I
authors.lastname: Jaiswal
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, India.
authors.forename: Mastan
authors.initials: M
authors.lastname: Singh
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, India.
authors.forename: Amita
authors.initials: A
authors.lastname: Jain
mesh_terms: D024901:Drug Resistance, Multiple, Bacterial; D054908:Extensively Drug-Resistant Tuberculosis / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology*; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D007538:Isoniazid / Q000627:therapeutic use; D007612:Kanamycin / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D015242:Ofloxacin / Q000627:therapeutic use; D012293:Rifampin / Q000627:therapeutic use; D018088:Tuberculosis, Multidrug-Resistant / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D007612:Kanamycin; D015242:Ofloxacin; D007538:Isoniazid; D012293:Rifampin