title: A simple and economical in-house phage technique for the rapid detection of rifampin, isoniazid, ethambutol, streptomycin, and ciprofloxacin drug resistance in Mycobacterium tuberculosis, directly on decontaminated sputum samples.
abstract: OBJECTIVE
  The early detection of drug resistance would be a boon for TB control programs. The aim of the present study was to set up a rapid phage assay for the testing of drug susceptibility of Mycobacterium tuberculosis to rifampin, isoniazid, ethambutol, streptomycin, and ciprofloxacin, directly on decontaminated sputum samples.
  
  
  METHODS
  Mueller-Hinton broth was used instead of 7H9 broth to make the method more economical. Vancomycin and polymyxin B were added to the concentrated sputum samples to reduce the bacterial contamination. The phage assay on decontaminated sputum samples was compared with the proportion method using M. tuberculosis isolates from the same sputum samples.
  
  
  RESULTS
  Phage assay results were available within 48h for rifampin and streptomycin and within 72h for all the other drugs. In contrast the proportion method required 4-6 weeks from the primary cultures. The sensitivity of the phage assay was in the range of 93% to 100% and specificity in the range of 96% to 100% for all the drugs tested. The interpretation of results was possible for 334 of the 370 (90.3%) acid-fast bacillus (AFB) smear-positive sputum samples by the phage assay.
  
  
  CONCLUSIONS
  The phage assay for the detection of drug resistance on direct decontaminated sputum samples is economical, easy to perform, and rapid.
authors.affiliation: Department of Microbiology, Immunology and Molecular Biology, Intermediate Referral Laboratory for Mycobacteriology, Choithram Hospital and Research Centre, Manik Bagh Road, Indore, MP 452014, India.
authors.forename: Nanda
authors.initials: N
authors.lastname: Hemvani
authors.forename: Vikas
authors.initials: V
authors.lastname: Patidar
authors.forename: D S
authors.initials: DS
authors.lastname: Chitnis
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D004977:Ethambutol / Q000494:pharmacology; D005260:Female; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods*; D050296:Microbial Viability / Q000187:drug effects; D008875:Middle Aged; D009160:Mycobacteriophages / Q000502:physiology*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000821:virology; D012293:Rifampin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D013307:Streptomycin / Q000494:pharmacology; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000382:microbiology; D014779:Virus Replication / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000904:Antibiotics, Antitubercular; D002939:Ciprofloxacin; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin; D013307:Streptomycin