Genetic profile of Mycobacterium tuberculosis and treatment outcomes in human pulmonary tuberculosis in Tanzania

Abstract

Information on the different spoligotype families of Mycobacterium tuberculosis in Tanzania is limited, and where available, restricted to small geographical areas. This article describes the genetic profile of M. tuberculosis across Tanzania and suggests how spoligotype families might affect drug resistance and treatment outcomes for smear positive pulmonary tuberculosis patients in Tanzania. We conducted the study from 2006 to 2008, and the isolates were obtained from samples collected under the routine drug resistance surveillance system. The isolates were from specimens collected from 2001 to 2007, and stored at the Central and Reference Tuberculosis Laboratory. A total of 487 isolates from 23 regions in the country were spoligotyped. We were able to retrieve clinical information for 446 isolates only. Out of the 487 isolates spoligotyped, 195(40.0%) belonged to the Central Asian (CAS) family, 84 (17.5%) to the Latin American Mediterranean (LAM) family, 49 (10.1%) to the East-African Indian (EAI) family, and 33 (6.8%) to the Beijing family. Other isolates included 1 (0.2%) for H37Rv, 10 (2.1%) for Haarlem, 4 (0.8%) for S family, 58 (11.9%) for T family and 52 (10.7%) for unclassified. No spoligotype patterns were consistent with M. bovis. Regarding treatment outcomes, the cure rate was 80% with no significant variation among the spoligotype families. The overall level of MDR TB was 2.5% (3/121), with no significant difference among the spoligotype families. All Beijing strains (11.8%, 30/254) originated from the Eastern and Southern zones of the country, of which 80% were from Dar es Salaam.Isolates from the CAS and T families were reported disproportionately from the Eastern-Southern zone, and EAI and LAM families from the Northern-Lake zones but the difference was not statistically significant. Five isolates were identified as non-tuberculous Mycobacteria. In conclusion, M. tuberculosis isolates from pulmonary tuberculosis cases in Tanzania were classified mostly within the CAS, LAM, and EAI and T families, while the Beijing family comprised about 7% isolates only. Consistently good treatment outcomes were recorded across these spoligotype families. The proportion of drug resistance strains was low. The findings also suggest variation of spoligotype families with varying geographical localities within the country, and identify this area for further research to confirm this finding. _________________________________________________________________________________

Molecular characterization of Mycobacterium tuberculosis isolates from Tanga, Tanzania: First insight of MIRU-VNTR and microarray-based spoligotyping in a high burden country

“…Similar families have been reported in variable proportions in other countries bordering Tanzania [31e35], indicating a geographical widespread of this group of spoligotypes in the region. These findings are also in agreement with those of other studies conducted in Tanzania which reported the predominance of these families [21,36,37].…”

“…Strain families previously reported in Tanzania but not reported in this study include the Haarlem genotype [21,37] and the X genotypes [21,36e38]. We detected a high proportion of T family isolates as found in previous studies [21,37].…”

“…Information on important aspects of TB epidemiology, such as role of recent transmission in reactivation of latent cases is still lacking. Available data on the different spoligotype families of MTB strains in Tanzania are limited, and where available restricted to small geographical areas [21].…”

Assessment of sputum smear-positive but culture-negative results among newly diagnosed pulmonary tuberculosis patients in Tanzania

“…NTM infection does not respond to anti-TB agents; however, the clinical impact of the indiscriminate use of anti-TB drugs in the tremendously, recently emerging drug-resistant TB era remains unassessed 2,24. Infection due to species of M. fortuitum and M. abscessus , which both have the capacity to cause respiratory infections in human, has previously been reported in Tanzania 25,26. Although this study did not conduct drug sensitivity testing, both M. fortuitum and M. abscessus can be misdiagnosed as resistant TB/multidrug-resistant TB due to their natural resistant pattern to antituberculosis drugs,15,26 which may result in unnecessary administration of toxic second-line anti-TB treatment.…”

Insights into the genetic diversity ofMycobacterium tuberculosisin Tanzania

“…These previous studies are limited as they only focused on few geographical locations and used spacer oligonucleotide typing (spoligotyping) technique which has limitations for phylogenetically robust strain classification [22,23]. Only one study profiled MTBC on a countrywide scale albeit with low sampling coverage [20].…”