Molecular typing and drug sensitivity testing of Mycobacterium tuberculosis isolated by a community-based survey in Ethiopia.

Muluwork Getahun,Abebaw Kebede,Zelalem Yaregal,Feven Girmachew,Feleke Dana,Almaz Abebe,Mulualem Agonafir,Grimay Medihn,Abyot Meaza,Yetnebersh Fiseha,Elena Hailu,Nathneal Dirse,Daniel Demssie,Eshetu Lemma,Zeleke Alebachew,Amha Kebede,Gobena Ameni,Fasil Tsegaye

doi:10.1186/s12889-015-2105-7

Muluwork Getahun, Abebaw Kebede + Show 16 more

Open Access

https://doi.org/10.1186/s12889-015-2105-7

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Abstract

BackgroundThe identification of circulating TB strains in the community and drug sensitivity patterns is essential for the tuberculosis control program. This study was undertaken to identify M. tuberculosis strains circulating in selected communities in Ethiopia as well as to evaluate the drug sensitivity pattern of these strains.MethodThis study was a continuation of the Ethiopian National TB Prevalence Survey that was conducted between 2010 and 2011. Culture-positive isolates of M. tuberculosis from previous study were typed using region of difference (RD) 9-based polymerase chain reaction (PCR) and spoligotyping. Drug sensitivity testing was conducted using the indirect proportion method on Lowenstein-Jensen media.ResultAll 92 isolates were confirmed as M. tuberculosis by RD9-based PCR and spoligotyping of 91 of these isolates leds to the identification of 41 spoligotype patterns. Spoligotype revealed higher diversity (45 %) and among this 65.8 % (27/41) were not previously reported. The strains were grouped into 14 clusters consisting of 2–15 isolates. The dominant strains were SIT53, SIT149 and SIT37 consisting of 15, 11, and 9 isolates, respectively. Our study reveals 70 % (64/91) clustered strains and only 39.1 % (25/64) occurred within the same Kebele. Further assignment of the strains to the lineages showed that 74.7 % (68/91) belonged to Euro-American lineage, 18.6 % (17/91) to East Africa Indian lineage and the remaining 6.5 % (6/91) belonged to Indo-oceanic lineage. Valid drug susceptibility test results were available for 90 of the 92 isolates. Mono-resistance was observed in 27.7 % (25/90) and poly-resistance in 5.5 % (5/90) of the isolates. Moreover, multi-drug resistance (MDR-TB) was detected in 4.4 % of the isolates whilst the rest (60/90) were susceptible to all drugs. The highest level of mono-resistance, 26.6 % (24/90), was observed for streptomycin with majority (91.1 %) of streptomycin mono-resistant strains belonging to the Euro-American lineage.ConclusionIn this study, the strains of M. tuberculosis circulating in selected sites of Ethiopia were identified along with the drug sensitivity patterns. Thus, these findings are useful for the TB Control Program of the country.

Highlights

The identification of circulating TB strains in the community and drug sensitivity patterns is essential for the tuberculosis control program
In this study, the strains of M. tuberculosis circulating in selected sites of Ethiopia were identified along with the drug sensitivity patterns
The WHO Global TB Report estimated that total of 480,000 people developed Multi-drug resistance (MDR)-TB worldwide in 2013

Summary

Introduction

The identification of circulating TB strains in the community and drug sensitivity patterns is essential for the tuberculosis control program. This study was undertaken to identify M. tuberculosis strains circulating in selected communities in Ethiopia as well as to evaluate the drug sensitivity pattern of these strains. There are an estimated 9 million new cases of TB every year. The prevalence of MDR-TB has been estimated to be 3.5 % in newly diagnosed cases and 20.5 % in previously treated TB cases [1]. According to the nationwide drug resistance survey conducted between 2003 and 2005 the overall prevalence of MDR-TB was 2.5 %. The prevalence of MDR-TB was 1.6 % and 11.8 % in newly diagnosed TB cases and previously treated cases, respectively [3]

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