The influence of HIV infection and imprisonment on dissemination of Mycobacterium tuberculosis in a large Spanish city

SETTING: Culture-positive cases of tuberculosis (TB) from the urban population of southern Madrid and from all the prisons located throughout the city.OBJECTIVE: To determine the frequency with which common strains of Mycobacterium tuberculosis cause disease among patients from both the urban and prison populations of a large Spanish city.DESIGN: Restriction fragment length polymorphism analysis was performed on culture-positive cases of TB identified between 1 January 1997 and 31 December 1998. Risk factors that might be associated with the dissemination of common strains of TB among the two populations were also investigated.RESULTS: Two hundred and twenty-one cases of culture-positive TB were identified, 99 (47.8%) of which were grouped in 23 clusters. Eleven were general clusters that spanned the prison and urban populations involved 69 patients (31.2%). Univariate analysis of risk factors showed that age