DNA fingerprinting and phenotyping of Mycobacterium tuberculosis isolates from human immunodeficiency virus (HIV)-seropositive and HIV-seronegative patients in Tanzania

Abstract

With the purpose of determining whether the risk of infection with a particular clone of Mycobacterium tuberculosis is influenced by the human immunodeficiency virus (HIV) status of the host, we analyzed and compared 68 mycobacterial isolates obtained from HIV-seropositive patients with tuberculosis (TB) in Dar esSalaam, Tanzania, with 66 mycobacterial isolates obtained from HIV-seronegative patients with TB in the same geographical region by using both DNA fingerprinting and classical phenotyping methods. One hundred one different IS6110 fingerprinting patterns were observed in the 134 isolates. The level of diversity of the DNA fingerprints observed in the HIV-seropositive group was comparable to the level of the diversity observed in the HIV-seronegative group. Resistance to a single anti-TB drug was found in 8.8% of the tested isolates, and 3.2% of the isolates were resistant to more than one anti-TB drug. The drug susceptibility profiles were not significantly difference between the two groups of isolates compared in the present study. Phenotypic characteristics which classify M. tuberculosis strains as belonging to the Asian subgroup correlated with a low IS6110 copy number per isolate. However, the occurrence of Asian subgroup strains was not associated with the HIV status of the patients. The results of the study suggested an equal risk of infection with a defined M. tuberculosis clone for HIV-seropositive and HIV-seronegative individuals.

Anti‐TB drug resistance levels and patterns among Mycobacterium tuberculosis isolated from newly diagnosed cases of pulmonary tuberculosis in Dar es Salaam, Tanzania

“…There was no mono resistance to rifampcin or ethambutol. These results are in accordance to those reported by Yang et al (12).…”

“…Multi-drug resistance was detected among 1.3% of the isolates. In Temeke during 1995, resistance to a single anti-TB drug was found in 8.8% of the tested isolates, 3.2% of the isolates were resistant to more than one anti-TB drug and none of the isolates were resistant to both isoniazid and rifampicin (12). Our results are also comparable with those of a study performed in Kilimanjaro (approximately 550 km north of Dar es Salaam) in which 10.8% of the 111 phenotypically tested strains were resistant to a single anti-TB drug and three (2.7%) were multi drug resistant (13).…”

“…Notably, resistance to individual drugs never exceeded 4%. However, it is worth noting that the limited number of Mtb strain families observed in Temeke (17) may be due to the relatively low discriminatory power of spoligotyping compared with the restriction fragment length polymorphism (RFLP) method used by Yang et al (12) that showed many RFLP patterns.…”

Molecular epidemiology of Mycobacterium tuberculosis strains isolated from patients in a human immunodeficiency virus cohort in Switzerland

“…In this cohort analysis we have found a large degree of IS6110 polymorphisms among the strains. The number of copies ranged from 1 to 16 elements (1 to 6 copies in 19.2% of the isolates, 7 to 11 copies in 65.4% of the isolates, and 12 to 16 in 15.4% of the isolates), similar to what has been reported previously (6,33). All strains had been identified as M. tuberculosis, including two (isolates 19 and 20) exhibiting only a single copy of IS6110 (verified by their strongly positive nitrate and niacin reactions, the aerophilic growth characteristics on Lebek medium, and their resistance to thiophene-2-carboxylic acid hydrazide which thus rules out their identity as Mycobacterium bovis [15]).…”

Molecular epidemiology of tuberculosis in Denmark in 1992

“…A clear correlation between occurrence of a low number of IS6110 elements per chromosome and classification into the Asian subgroup of M. tuberculosis strains was observed in a previous study in Tanzania (25). In another study, one third of the M. tuberculosis strains from Asia were found to contain only a single copy of the IS6110 element (20).…”