The contribution of ethnicity to Mycobacterium tuberculosis strain clustering

OBJECTIVE: Descriptive study of molecular epidemiologic patterns of tubercu losis cases among ethnic minorities in Houston, Texas. DESIGN: Population-based, prospective, active surveillance, and molecular e pidemiology study. PATIENTS: Tuberculosis cases reported to the City of Houston Tuberculosis C ontrol Office between October 1995 and September 1998. RESULTS: During the study period, 1133 culture-positive patients were enrol led for whom isolates of their culture specimen were available. Of these, 3 10 were part of an ethnic minority. Molecular characterization identified 6 89 of 1139 isolates to be clonally related. Factors significantly associate d with tuberculosis strain clustering in a multivariable logistic regressio n analysis were: birth in the United States, a history of homelessness, inf ection with the human immunodeficiency virus (HIV), pulmonary disease, infe ction with a tuberculosis strain from principal genetic group 1 or 3, livin g in a residence with five or more persons present, and use of public trans portation more than once weekly. Asian ethnicity and increasing age were as sociated with decreased odds of clustering. CONCLUSIONS: Ethnicity was not a significant covariate for strain clusterin g after adjustments for factors related to socio-economic status.