[The Mycobacteria Growth Indicator Tube (MGIT) is useful for anticipating the resistance of Mycobacterium tuberculosis to rifampicin but not to isoniazid].
A previously proposed MGIT protocol was assessed focussing on its reliability to test the mainstay antituberculous drugs. Isoniazid (H) (0.1 mg/l) and rifampin (R) (1 mg/l) were assayed against 109 Mycobacterium tuberculosis isolates affecting patients at high risk of multidrug-resistant tuberculosis. All isolates were simultaneously tested on Löwenstein-Jensen medium by the proportion method considered the gold standard. MGIT readings were accomplished within 2 and 22 days after inoculation, at day 10, 93.4% of the tests were completed. Unsatisfactory to evaluate H activity, the assay misclassified 8.8% (5/57) H susceptible and 7.7% (4/52) H resistant isolates. Otherwise, it yielded correct results for all 60 R susceptible isolates and 93.9% (46/49) R resistant isolates. Properly backed-up by a conventional test and targeting high risk patients, the MGIT system proved to be a useful aid to anticipate most of resistance to R. Accuracy, cost and turnaround time were competitive compared with those of semi-automated culture-based or molecular methods.
Avendaño
D
D
Servicio de Micobacterias, Instituto Nacional de Enfermedades Infecciosas, A.N.L.I.S. Dr. Carlos G. Malbrán, Avda. Vélez Sarsfield 563, 1281 Buenos Aires, Argentina. davendanyo@anlis.gov.ar
López
B
B
Símboli
N
N
Masciotra
N
N
Barrera
L
L
D000995:Antitubercular Agents / Q000494:pharmacology*; D003470:Culture Media; D004351:Drug Resistance; D024901:Drug Resistance, Multiple, Bacterial; D005188:False Negative Reactions; D015658:HIV Infections / Q000150:complications; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D011933:Reagent Kits, Diagnostic; D012008:Recurrence; D012015:Reference Standards; D012293:Rifampin / Q000494:pharmacology*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000150:complications / Q000382:microbiology
D000995:Antitubercular Agents; D003470:Culture Media; D011933:Reagent Kits, Diagnostic; D007538:Isoniazid; D012293:Rifampin