A population-based study of drug resistance and transmission of tuberculosis in an urban community.

Setting: A low-income neighborhood of Sao Paulo, Brazil.
Objective: To determine the incidence, risk factors and transmission patterns of multidrug-resistant tuberculosis (MDR-TB).
Design: Prospective longitudinal study of patients with pulmonary TB (PTB).
Methods: Sputum culture-confirmed patients with PTB were recruited between March 2000 and May 2002. Bivariate and multivariate logistic regression analyses were performed to identify factors associated with MDR-TB. Mycobacterium tuberculosis isolates were tested for drug susceptibility and typed by IS6110-RFLP analysis.
Results: Of 420 patients, respectively 71% and 27% were new and previously treated; 15.5% of the patients' M. tuberculosis isolates were resistant to at least one drug; of these, 11% and 27% were found among new and previously treated cases, respectively. Respectively 1% and 16.7% of the new and previously treated cases were MDR-TB. RFLP analysis showed that new transmission of MDR strains was uncommon. By multivariate logistic regression analysis, previous TB and hospitalization in the 24 months before TB diagnosis were identified as independent predictors of MDR-TB.
Conclusions: The results showed an intermediate level of MDR-TB incidence in a neighborhood of Sao Paulo and identified predictors that can be targeted for intervention by national and local TB control programs.