DISSEMINATION OF MYCOBACTERIUM-TUBERCULOSIS ACROSS THE SAN-FRANCISCO BAY AREA

The propensity of Mycobacterium tuberculosis genotypes to spread acros s geographic boundaries was investigated by comparing the IS6110 and p olymorphic GC-rich sequence patterns of M. tuberculosis isolates from San Francisco and the East Bay, two distinct regions separated by San Francisco Bay. Of 724 isolates from incident tuberculosis patients dur ing 1992 and 1993, only 53 (7.3%) had patterns matching greater than o r equal to 1 isolates from the other region. In the multivariable anal ysis of patient risk factors, an AIDS diagnosis (odds ratio [OR], 1.89 ; 95% confidence interval [CI], 1.00-3.57) and non-Asian race (OR, 3.4 3; 95% CI, 1.59-7.42) were associated with having an isolate with a ma tching pattern. Of 375 unique IS6110 patterns among San Francisco isol ates, only 9 (2.4%) matched patterns of East Bay isolates. These popul ation-based data suggest that in the San Francisco Bay Area, M. tuberc ulosis does not rapidly spread across geographic boundaries, and tuber culosis control efforts should focus on transmission within defined ar eas.