title: In-house, simple & economical phage technique for rapid detection of rifampicin, isoniazid, ethambutol, streptomycin & ciprofloxacin drug resistance using Mycobacterium tuberculosis isolates.
abstract: OBJECTIVE
  Multiple drug resistance (MDR) among Mycobacterium tuberculosis poses a serious therapeutic problem. Early detection of MDR can be valuable but the conventional drug susceptibility tests take 4-6 wk time after the laboratory isolation of M. tuberculosis. The bacterial phage assay has been reported as a rapid tool for rifampicin susceptibility testing of tubercle bacilli using the suspension of isolated cultures. The present study was aimed to set up a phage assay for testing drug susceptibility to isoniazid (INH), rifampicin, ethambutol, streptomycin and ciprofloxacin in M. tuberculosis isolates.
  
  
  METHODS
  Mueller-Hinton broth instead of Middle Brook 7H9 broth was used to make it more economical. The phage assay was compared with the proportion method using 100 M. tuberculosis isolates from pulmonery TB cases. Phage assay results were available in 48 h for rifampicin and streptomycin while 72 h required for INH, ethambutol and ciprofloxacin. The assay was compared with gold standard proportion method. Interpretation of the results was easy and clear.
  
  
  RESULTS
  In the present study, sensitivity and specificity of the phage assay when compared to proportion method were in the range of 97 to 100 per cent for all the drugs except for ciprofloxacin for which it was 93 and 96 per cent, respectively.
  
  
  CONCLUSIONS
  The phage assay was economic, easy to perform and rapid for the detection of drug resistance in M. tuberculosis isolates with no requirement of expensive equipment. It is within the reach of microbiology laboratories in developing countries having high loads of tuberculosis.
authors: Department of Microbiology, Immunology & Molecular Biology, Choithram Hospital & Research Centre, Indore, India.
authors: Nanda
authors: N
authors: Hemvani
authors: Vikas
authors: V
authors: Patidar
authors: D S
authors: DS
authors: Chitnis
mesh_terms: D000995:Antitubercular Agents / Q000627:therapeutic use; D001435:Bacteriophages; D002939:Ciprofloxacin / Q000627:therapeutic use; D004977:Ethambutol / Q000627:therapeutic use; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification*; D012293:Rifampin / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D013307:Streptomycin / Q000627:therapeutic use; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000235:genetics* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D002939:Ciprofloxacin; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin; D013307:Streptomycin