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

Abstract

BackgroundThe identification and differentiation of strains of Mycobacterium tuberculosis 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.MethodsOne hundred eighty three isolates of Mycobacterium tuberculosis from 80 HIV seropositive and 103 HIV seronegative patients were fingerprinted by standard IS6110-RFLP. Using the BioNumerics software, strains were considered to be clustered if at least one other patient had an isolate with identical RFLP pattern.ResultsOne 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 IS6110 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, P = 0.615), patients aged <40 years (aOR 0.53, 95%CI 0.25–1.12, P = 0.100), and sex (aOR 1.12, 95%CI 0.60–2.06, P = 0.715).ConclusionThe 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.

Mycobacterium tuberculosis Transmission in a Country with Low Tuberculosis Incidence: Role of Immigration and HIV Infection

“…The clinical care and close follow-up provided in a clinical cohort (10) might have further reduced transmission and might explain the lower clustering in HIV-infected patients, compared to HIV-negative patients. Of note, TB among the HIV-infected population was at least partly due to transmissions from HIVnegative individuals, consistent with reports from countries with high TB and HIV burdens (2).…”

IS6110 the Double-Edged Passenger

“…The number of IS6110 copies ranged from 1 to 20 and the frequency of occurrence of IS6110 bands was similar between the two serogroups. The most prevalent pattern observed had 14 copies of IS6110 with the same distribution comparing HIV seropositive and HIV seronegative patients (Asiimwe et al, 2009). …”

“…Several studies illustrate the situation in the highest TB incidence areas, such as two areas of India (Shanmugam et al, 2011;Purwar et al, 2011) or Uganda (Asiimwe et al, 2009). Other study that gives an overview of the distribution of genotypes of M. tuberculosis in Korea, found that drug resistance phenotypes were more strongly associated with Beijing family (see part 4.1.3).…”

Distribution and transmission of Mycobacterium tuberculosis complex lineages among children in peri-urban Kampala, Uganda

“…Two approaches have been used to define MTB transmission in a community. The first uses MTBC phylogenetic clustering to signify on-going transmission (recent transmission) and the presence of unique strains as indicators of reactivation of latent TB infections [ 4 , 14 , 15 ]. A second approach defines transmission through pediatric TB, since children progress faster from recent MTB infection to disease than adults, in part because of immune system immaturity resulting in rapid disease progression rather than latency [ 16 – 18 ].…”