Epidemiologic differences between United States- and foreign-born tuberculosis patients in Houston, Texas

The proportion of foreign-born tuberculosis patients in the United States is increasing. To analyze the epidemiology of tuberculosis in foreign-born people, culture-positive patients with tuberculosis in Houston, Texas, were interviewed from October 1995 through September 1998, and their isolates were molecularly characterized. Of the 1131 patients included in the study, 795 (70.3%) were US born and 336 (29.7%) were foreign born. The decrease in tuberculosis case rate among US-born people was 3.5 times that of foreign-born people. Significantly more US-born than foreign-born patients belonged to strain clusters (71.3% vs. 29.5%; P<.001). Risk factors associated with strain clustering were as follows: black ethnicity, low income, and homelessness in US-born patients and homelessness in foreign-born patients. Isolates from foreign-born patients were more likely to be resistant to >/=1 drug (15.4% vs. 8.4%; P=.001) and to be multidrug resistant (2.4% vs. 0.7%; P=.027) than isolates from US-born patients. These observations warrant increased emphasis on this distinct subpopulation of tuberculosis patients.