Drug-resistant tuberculosis: A disease of target populations in Houston, Texas

Objectives: To analyse the traditional and molecular epidemiology of drug-resistant tuberculosis (DRTB) in Houston and Harris County, Texas in the setting of decreasing disease incidence. Methods: Case-control study of 193 patients with DRTB and 1977 patients with drug-susceptible TB (DSTB) identified from a population-based surveillance, 1995-2001. Results: In a multivariate logistic regression, the following risk factors were found to be predictors of having DRTB (P≤0.05): human immunodeficiency virus (HIV) seropositivity, Hispanic ethnicity, Asian ethnicity, history of past TB; whereas being foreign born, having a history of past TB, and younger age were predictors of MDRTB. There were 15 patients who acquired drug resistance while on therapy, and they were significantly more likely than controls to be HIV-seropositive, be of Asian ethnicity, have smear-positive pulmonary disease and present with pleural effusion on chest radiograph. No difference in 6-month mortality between DRTB and DSTB cases was found. During the study period, the incidence of DRTB remained constant. Conclusions: In Houston, there is a steady, low-level, incidence of DRTB which disproportionately affects specific subpopulations, with no evidence of increased mortality at 6 months.