Resistencia aos farmacos antimicobacterianos em um hospital terciario : utilidade do metodo de microdiluição em placa com sal de tetrazolium / Susceptibility of M. Tuberculosis to first-line antimycobacterial agents in Brazilian hospital : asessing the utility of the tetrazolium (MTT) microplate assay

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This cross-sectional, hospital-based study conducted between January 2006 and March 2008 sought to estimate the resistance of M. tuberculosis to first-line drugs among patients with tuberculosis confirmed by culture at a Brazilian hospital and evaluate the performance of the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] (MTT) microplate assay in comparison to the Bactec MGIT 960. During the study period were reported to the surveillance system 360 tuberculosis cases, 211 out of these were confirmed by positive culture for Mycobacterium sp and 105 out of these had M. tuberculosis isolated on culture and were included to the prevalence study. Pulmonary involvement was present in 64.8% of cases and HIV co-infection was found in 37.1%. The prevalence of M. tuberculosis resistance was 6.7%; multidrug-resistance [rifampin (RMP) and isoniazid (INH)] and resistance to INH and streptomycin (SM) were detected in 1%, in 3.8% and in 3.8% of cases, respectively. All isolates were susceptible to ethambutol (EMB). The resistance was primary in four cases and acquired in three cases. Previous treatment was associated with resistance (p=0.0181). Among 119 isolates of M. tuberculosis included to the MMTT performance evaluation, there was 100% observed agreement for INH and EMB between the MTT and Bactec MGIT 960™ methods. For RMP, the observed agreement was 99% (sensitivity: 90%), and for SM, the level of agreement was lower (95.2%; sensibility 90.9%) than those of the other drugs. The prevalence of M. tuberculosis resistance among the new cases during the study period was 6.7%; multidrug-resistance and resistance to INH and streptomycin (SM) were detected in 1%, in 3.8% and in 3.8% of cases, respectively. The colorimetric method with tetrazolium (MTT) represents an accurate, simple and low cost alternative that is both viable and sustainable for settings with limited resources.

ASSUNTO(S)

drug resistance drogas - resistencia tuberculose teste de suscetibilidade tuberculosis drug susceptibility test

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