DNA fingerprinting of a national sample of Mycobacterium tuberculosis isolates, Botswana, 1995-1996.

DNA fingerprinting may be useful to elucidate tuberculosis (TB) transmission in community settings, but its utility is limited if only few fingerprint patterns are observed or band numbers are low. We performed DNA fingerprinting on a national, population-based sample of Mycobacterium tuberculosis isolates from Botswana. During 1995-1996, a random sample of 213 isolates, representing 5% of all smear-positive TB cases, underwent DNA fingerprinting using restriction fragment length polymorphism (RFLP) IS6110 analysis. Eighty-two (38%) of the 213 isolates belonged to one of 18 clusters, with 2-9 isolates/cluster. The median number of bands was 10 (range 1-19); 183 (86%) had six or more bands. Sixty-three (49%) of 128 patients tested were infected with the human immunodeficiency virus (HIV). The degree of RFLP pattern heterogeneity and high band number support the feasibility of a prospective DNA fingerprinting study in Botswana.