The majority of patients with multidrug-resistant tuberculosis in Sub-Saharan Africa present a concomitant resistance to pyrazinamide

Géraldine Daneau; Mourad Gumusboga; Pim De Rijk; Arnaud Trebucq; Leen Rigouts; Armand Van Deun; Bouke C de Jong

doi:10.1016/j.ijmyco.2016.10.015

The majority of patients with multidrug-resistant tuberculosis in Sub-Saharan Africa present a concomitant resistance to pyrazinamide

Int J Mycobacteriol. 2016 Dec:5 Suppl 1:S46-S47. doi: 10.1016/j.ijmyco.2016.10.015. Epub 2016 Oct 27.

Authors

Géraldine Daneau¹, Mourad Gumusboga², Pim De Rijk², Arnaud Trebucq³, Leen Rigouts⁴, Armand Van Deun⁵, Bouke C de Jong²

Affiliations

¹ Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. Electronic address: gdaneau@itg.be.
² Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
³ International Union against Tuberculosis and Lung Disease (The Union), Paris, France.
⁴ Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. Electronic address: lrigouts@itg.be.
⁵ Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium; International Union against Tuberculosis and Lung Disease (The Union), Paris, France.

PMID: 28043604
DOI: 10.1016/j.ijmyco.2016.10.015

Abstract

Objective/background: Pyrazinamide (PZA) is an antibacterial used in the first-line regimen against tuberculosis (TB) for its action against dormant bacilli. PZA is also included in the new short regimen to treat multidrug-resistant TB (MDR-TB). However, the prevalence and significance of PZA resistance is not known in Central and West Africa.

Methods: Between 2013 and 2016, we collected samples from MDR-TB patients recruited in an observational study implementing the new short MDR-TB regimen in six countries: Burundi (n=35), Cameroon (n=135), Niger (n=57), Central African Republic (n=35), Democratic Republic of the Congo (n=99), and Rwanda (n=16). Resistance to rifamipicine, isoniazide, injectables, and fluoroquinolones was tested by phenotypic (live strains) or genotypic methods (inactivated strains). Resistance to PZA was analyzed through sequencing of the pncA gene. Relevance of mutations was established based on recent literature.

Results: From 377 patients with MDR-TB, 354 (94%) samples were successfully sequenced. Among those, 53% (189) presented a mutation in pncA that confers a reported (121), potential (56), or unclear (12) resistance. Furthermore, six isolates presented a mutation associated with PZA sensitivity. The frequency of resistance per country was 26% in Central African Republic, 39% in Niger, 49% in Cameroon, 66% in Burundi, 68% in Democratic Republic of the Congo, and 87% in Rwanda. Isolates presented 109 different profiles of mutations, including 73 occurring only once. Codon 12 was most frequently affected (15 isolates), including 10 isolates with Asp12Ala. These 10 isolates came from three different countries, and presented different profiles of resistance to other drugs. The two next most frequent mutations, Met175Ile and Gln10Pro (8 isolates and 7 isolates, respectively), each suggest clusters of transmission, with similar geographical and resistance characteristics. Moreover, four isolates presented two simultaneous genetic variations, and 11 patients had a mix of sensitive and resistant bacilli. Preliminary data tend to indicate that patients carrying a PZA-resistant isolate had a higher failure rate on the new short MDR-TB treatment regimen (7% vs. 3%). All isolates resistant to injectables (4) and most (19/21) of those resistant to fluoroquinolones, including two extremely-resistant TB isolates, were also resistant to PZA.

Conclusion: Similar to other regions in the world, the majority of MDR-TB strains from Sub-Saharan Africa countries are resistant to PZA, albeit with diverse rates between countries. We identified a diverse range of mutations in pncA, with 30% of them not previously reported. The impact of such resistance on the success of the short MDR-TB regimen will require more investigation.

Keywords: MDR-TB; Mutation; Pyrazinamide (PZA); Resistance; Tuberculosis; pncA.