Restriction fragment length polymorphism analysis detecting a community-based tuberculosis outbreak among persons...

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.