Restriction fragment length polymorphism analysis detecting a community-based tuberculosis outbreak among persons infected with human immunodeficiency virus.

Analysis of restriction fragment length polymorphisms (RFLP) was used to investigate an increase in tuberculosis (TB) among noninstitutionalized human immunodeficiency virus (HIV)-infected persons in King County, Washington. Using the IS6110 insertion sequence, RFLP analysis was done on Mycobacterium tuberculosis isolates from 18 HIV-infected patients and 10 randomly selected patients without HIV risk factors. Six HIV-infected patients with the same M. tuberculosis strain had contact at one or more of three bars as their only common exposure. Two other HIV-infected persons, a patient and a health care worker who had close contact, had matching strains. Isolates from the 10 remaining HIV-infected patients and the 10 patients without HIV risk factors had different DNA patterns. Analysis of RFLP patterns revealed a community outbreak of TB among HIV-infected persons who had not been previously linked following conventional investigation by the health department. This technique deserves further evaluation as an epidemiologic tool in the investigation of TB.