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Second-line anti-tuberculosis drug resistance testing in Ghana identifies the first extensively drug-resistant tuberculosis case

Authors Osei-Wusu S, Amo Omari M, Asante-Poku A, Darko Otchere I, Asare P, Forson A, Otu J, Antonio M, Yeboah-Manu D

Received 27 September 2017

Accepted for publication 30 November 2017

Published 22 February 2018 Volume 2018:11 Pages 239—246


Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Akshita Wason

Peer reviewer comments 2

Editor who approved publication: Dr Sahil Khanna

Stephen Osei-Wusu,1,2 Michael Amo Omari,3 Adwoa Asante-Poku,1 Isaac Darko Otchere,1 Prince Asare,1 Audrey Forson,3 Jacob Otu,4 Martin Antonio,4 Dorothy Yeboah-Manu1

1Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana; 2West Africa Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana; 3Department of Chest Diseases, Korle-Bu Teaching Hospital, Accra, Ghana; 4Medical Research Council Unit, Fajara, The Gambia

Background: Drug resistance surveillance is crucial for tuberculosis (TB) control. Therefore, our goal was to determine the prevalence of second-line anti-TB drug resistance among diverse primary drug-resistant Mycobacterium tuberculosis complex (MTBC) isolates in Ghana.
Materials and methods:
One hundred and seventeen MTBC isolates with varying first-line drug resistance were analyzed. Additional resistance to second-line anti-TB drugs (streptomycin [STR], amikacin [AMK] and moxifloxacin [MOX]) was profiled using the Etest and GenoType MTBDRsl version 2.0. Genes associated with resistance to AMK and MOX (gyrA, gyrB, eis, rrs, tap, whiB7 and tlyA) were then analyzed for mutation.
Results: Thirty-seven (31.9%) isolates had minimum inhibitory concentration (MIC) values ≥2 µg/mL against STR while 12 (10.3%) isolates had MIC values ≥1 µg/mL for AMK. Only one multidrug-resistant (MDR) isolate (Isolate ID: TB/Nm 919) had an MIC value of ≥0.125 µg/mL for MOX (MIC = 3 µg/mL). This isolate also had the highest MIC value for AMK (MIC = 16 µg/mL) and was confirmed as resistant to AMK and MOX by the line probe assay GenoType MTBDRsl version 2.0. Mutations associated with the resistance were: gyrA (G88C) and rrs (A514C and A1401G).
Conclusion: Our findings suggest the need to include routine second-line anti-TB drug susceptibility testing of MDR/rifampicin-resistant isolates in our diagnostic algorithm.

Keywords: tuberculosis, drug resistance, diagnosis, Ghana, XDR

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