RFLP patterns and risk factors for recent tuberculosis transmission among hospitalized tuberculosis patients in Rio de Janeiro, Brazil

Isolates of Mycobacterium tuberculosis from 120 tuberculosis patients seen in the 12 months ending September 1994 at 2 tertiary-care centres in Rio de Janeiro were characterized by IS6110 restriction fragment length polymorph ism (RFLP) analysis. Ninety-seven patients (81%) had isolates with unique R FLP patterns, while 23 patients (19%) had isolates that belonged to 11 diff erent RFLP cluster patterns. The strains from the latter patients were dist ributed among 1 group of 3 patients and 10 groups of 2 patients each. The c luster-pattern strains were not associated with gender, age, HIV infection, type of residence, living in shelter, homelessness or previous history of tuberculosis. However, clustering was strongly associated with multidrug re sistance (P = 0.006). These data suggest that recent exogenous transmission may be important for the development of new cases of multidrug-resistant d isease in patients attending tertiary-care centres in Rio de Janeiro, Brazi l.