Multidrug-resistant Mycobacterium tuberculosis at a referral center for infectious diseases in the state of Minas Gerais, Brazil: sensitivity profile and related risk factors

To assess the determining factors for Mycobacterium tuberculosis multidrug resistance at a referral center for infectious diseases in the state of Minas Gerais, Brazil. A retrospective case-control study was conducted using data collected from September of 2000 to January of 2004. During this period, 473 cultures presenting growth of M. tuberculosis, corresponding to 313 patients, were submitted to susceptibility tests at the Central Laboratory of Minas Gerais. Cases presenting resistance to at least rifampin and isoniazid were classified as cases of multidrug resistance and were selected for study. These cases were paired to control group cases of drug-susceptible tuberculosis at a ratio of 1:3. Clinical and demographic data were analyzed using univariate and multivariate analyses. During the study period, 12 (3.83%) cases of multidrug-resistant tuberculosis were identified. In the univariate analysis, multidrug-resistant tuberculosis was found to be more common among male patients, as well as among those testing positive in the sputum smear microscopy, those with cavitations larger than 4 cm in diameter and those having been previously treated for tuberculosis (p = 0.10 for all). After the multivariate analysis, only previous treatment for tuberculosis remained statistically significant (p = 0.0374), with an odds ratio of 14.36 (1.96-176.46). In the present study, previous treatment for tuberculosis was found to be an independent risk factor for multidrug-resistant tuberculosis.