Drug resistance of strains of Mycobacterium tuberculosis isolated in Brazil

Tuberculosis remains a serious public health problem, worsened by an increa sed frequency of multidrug-resistant Mycobacterium tuberculosis. We report here a retrospective study of resistance to antituberculosis drugs of 170 s trains of M. tuberculosis isolated from the state of Rio Grande do Sul, Bra zil. The frequency of resistance to at least one drug was 34%, while 22% we re resistant to more than one drug. Among the strains isolated from patient s without a history of previous treatment for tuberculosis, patients with p ositive serology for HIV and patients with previous treatment for tuberculo sis, the resistance to at least one drug was 14, 27 and 73%, respectively. Multidrug-resistant tuberculosis, defined as resistant to at least rifampic in (RMP) and isoniazid (INH), was found in the groups of patients without p revious treatment, HIV co-infected and with previous treatment for tubercul osis at 10, 17 and 44%, respectively. With the purpose of evaluating whethe r the sensitivity test to INH and RMP would be a good marker to indicate re sistance to other antituberculosis drugs, sensitivity tests were performed with four more drugs in 32 strains, initially classified as resistant to IN H, RMP or both. Of 18 strains resistant to INH and RMP simultaneously, 89% showed resistance to four more drugs. (C) 2001 Editions scientifiques et me dicales Elsevier SAS.