DNA restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolates from HIV-seropositive and HIV-seronegative patients in Kampala, Uganda

<p>Abstract</p> <p>Background</p> <p>The identification and differentiation of strains of <it>Mycobacterium tuberculosis </it>by DNA fingerprinting has provided a better understanding of the epidemiology and tracing the transmission of tuberculosis. We set out to determine if there was a relationship between the risk of belonging to a group of tuberculosis patients with identical mycobacterial DNA fingerprint patterns and the HIV sero-status of the individuals in a high TB incidence peri-urban setting of Kampala, Uganda.</p> <p>Methods</p> <p>One hundred eighty three isolates of <it>Mycobacterium tuberculosis </it>from 80 HIV seropositive and 103 HIV seronegative patients were fingerprinted by standard IS<it>6110</it>-RFLP. Using the BioNumerics software, strains were considered to be clustered if at least one other patient had an isolate with identical RFLP pattern.</p> <p>Results</p> <p>One hundred and eighteen different fingerprint patterns were obtained from the 183 isolates. There were 34 clusters containing 54% (99/183) of the patients (average cluster size of 2.9), and a majority (96.2%) of the strains possessed a high copy number (≥ 5 copies) of the IS<it>6110 </it>element. When strains with <5 bands were excluded from the analysis, 50.3% (92/183) were clustered, and there was no difference in the level of diversity of DNA fingerprints observed in the two sero-groups (adjusted odds ratio [aOR] 0.85, 95%CI 0.46–1.56, <it>P </it>= 0.615), patients aged <40 years (aOR 0.53, 95%CI 0.25–1.12, <it>P </it>= 0.100), and sex (aOR 1.12, 95%CI 0.60–2.06, <it>P </it>= 0.715).</p> <p>Conclusion</p> <p>The sample showed evidence of a high prevalence of recent transmission with a high average cluster size, but infection with an isolate with a fingerprint found to be part of a cluster was not associated with any demographic or clinical characteristics, including HIV status.</p