Rapid, automated, nonradiometric susceptibility testing of Mycobacterium tuberculosis complex to four first-line antituberculous drugs used in standard short-course chemotherapy.
The increasing prevalence of drug-resistant tuberculosis necessitates rapid and accurate susceptibility testing. The nonradiometric BACTEC Mycobacteria Growth Indicator Tube 960 (MGIT) system for susceptibility testing was evaluated on 222 clinical Mycobacterium tuberculosis complex isolates for isoniazid, rifampin, and ethambutol. Fifty-seven of the isolates were tested for pyrazinamide. Results were compared to those of radiometric BACTEC 460 system and discrepancies were resolved by the agar proportion method. We found an overall agreement of 99.0% for isoniazid, 99.5% for rifampin, 98.2% for ethambutol, and 100% for pyrazinamide. After resolution of discrepancies, MGIT yielded no false susceptibility for rifampin and isoniazid. Although turnaround times were comparable, MGIT provides an advantage as inoculation can be done on any weekday as the growth is monitored automatically. The automated MGIT system is a rapid and reliable alternative for susceptibility testing of M. tuberculosis complex to first-line drugs.
International Reference Laboratory of Mycobacteriology, Statens Serum Institut, National Institute for Prevention and Control of Infectious Diseases and Congenital Disorders, Copenhagen, Denmark. isj@ssi.dk
Isik Somuncu
IS
Johansen
Vibeke Østergaard
VØ
Thomsen
Merja
M
Marjamäki
Anaida
A
Sosnovskaja
Bettina
B
Lundgren
D000995:Antitubercular Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003470:Culture Media; D024901:Drug Resistance, Multiple, Bacterial; D004977:Ethambutol / Q000494:pharmacology; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000295:instrumentation / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000254:growth & development*; D011718:Pyrazinamide / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis / Q000188:drug therapy
D000995:Antitubercular Agents; D003470:Culture Media; D011718:Pyrazinamide; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin