Recurrent tuberculosis in Houston, Texas: a population-based study

OBJECTIVE: To determine the predictors of recurrence of tuberculosis (TB), the drug resistance pattern of Mycobacterium tuberculosis strains recovered from recurrent TB patients, and the frequency of re-infection with a new M. tuberculosis strain among patients with recurrent disease. DESIGN: A population-based, retrospective case-control study using the Houston Tuberculosis Initiative database. RESULTS: We found that, among 100 patients with recurrent TB who completed adequate therapy for a first episode of TB, not receiving directly observed therapy, pulmonary disease, HIV/AIDS diagnosis, not having a family physician, being unemployed and using public transportation were predictors of recurrent disease. There was a significant increase in drug-resistant M. tuberculosis strains in the second episode of disease compared to the first episode (21.3% vs. 8.2%, P = 0.04). Exogenous re-infection with a new strain of M. tuberculosis was found to cause 24-31% of recurrent TB. CONCLUSION: Recurrent TB in Houston is associated with a significant increase in drug-resistant M. tuberculosis strains. Re-infection with a new M. tuberculosis strain causes a significant proportion of recurrent TB in an area of low TB incidence. Patients with HIV/AIDS constitute a population at increased risk of disease recurrence.