title: Risk factors for MDR and XDR-TB in a tertiary referral hospital in India.
abstract: BACKGROUND
  India has a high burden of drug resistant TB, although there are few data on XDR-TB. Although XDR-TB has existed previously in India, the definition has not been widely applied, and surveillance using second line drug susceptibility testing has not been performed. Our objective was to analyze clinical and demographic risk factors associated with isolation of MDR and XDR TB as compared to susceptible controls, at a tertiary center.
  
  
  RESULTS
  Retrospective chart review based on positive cultures isolated in a high volume mycobacteriology laboratory between 2002 and 2007. 47 XDR, 30 MDR and 117 susceptible controls were examined. Drug resistant cases were less likely to be extrapulmonary, and had received more previous treatment regimens. Significant risk factors for XDR-TB included residence outside the local state (OR 7.43, 3.07-18.0) and care costs subsidized (OR 0.23, 0.097-0.54) in bivariate analysis and previous use of a fluoroquinolone and injectable agent (other than streptomycin) (OR 7.00, 95% C.I. 1.14-43.03) and an initial treatment regimen which did not follow national guidelines (OR 5.68, 1.24-25.96) in multivariate analysis. Cavitation and HIV did not influence drug resistance.
  
  
  CONCLUSIONS
  There is significant selection bias in the sample available. Selection pressure from previous treatment and an inadequate initial regimen increases risk of drug resistance. Local patients and those requiring financial subsidies may be at lower risk of XDR-TB.
authors.affiliation: Department of Microbiology, Christian Medical College Vellore, Vellore, Tamil Nadu, India.
authors.forename: V
authors.initials: V
authors.lastname: Balaji
authors.forename: Peter
authors.initials: P
authors.lastname: Daley
authors.forename: Alok Azad
authors.initials: AA
authors.lastname: Anand
authors.forename: Thambu
authors.initials: T
authors.lastname: Sudarsanam
authors.forename: Joy Sarojini
authors.initials: JS
authors.lastname: Michael
authors.forename: Rani Diana
authors.initials: RD
authors.lastname: Sahni
authors.forename: Poorvi
authors.initials: P
authors.lastname: Chordia
authors.forename: Ige Abraham
authors.initials: IA
authors.lastname: George
authors.forename: Kurien
authors.initials: K
authors.lastname: Thomas
authors.forename: Alka
authors.initials: A
authors.lastname: Ganesh
authors.forename: K R
authors.initials: KR
authors.lastname: John
authors.forename: Dilip
authors.initials: D
authors.lastname: Mathai
mesh_terms: D000293:Adolescent; D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use; D054908:Extensively Drug-Resistant Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D024841:Fluoroquinolones / Q000627:therapeutic use; D006761:Hospitals; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000378:metabolism; D012189:Retrospective Studies; D012306:Risk; D012307:Risk Factors; D013307:Streptomycin / Q000627:therapeutic use; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000453:epidemiology*
chemical_list: D000995:Antitubercular Agents; D024841:Fluoroquinolones; D013307:Streptomycin