Molecular insights into carbapenemase-producing Enterobacterales from Senegal.

Background: Carbapenemase-producing Enterobacterales (CPE) are an urgent global health threat, especially in resource-limited countries. Here we determined the prevalence and the molecular characteristics of CPE isolated from infections in Dakar, Senegal.

Method: From January 2019 to December 2020, Enterobacterales with reduced susceptibility to ertapenem (diameter < 25 mm) from infections were collected at the Pasteur Institute of Dakar. Carbapenemases were detected using biochemical and immunochromatographical assays. WGS was used to determine resistome, MLST, plasmids, virulence genes and genetic relatedness.

Results: Of the 1045 Enterobacterales collected during the study period, 86 had a diameter around ertapenem of <25 mm (8%) and 19 were confirmed as CPE (2%). These included Escherichia coli (n = 6) [ST410 (n = 3), ST405 (n = 2) and ST2083], Enterobacter spp. (n = 6) [ST231 (n = 3), ST245, ST760 and ST960] and Klebsiella spp. (n = 5) (ST22, ST25, ST231, ST1535, ST4843), Citrobacter freundii ST22 (n = 1) and Citrobacter koseri with unknown ST (n = 1). blaOXA-48 (n = 7; 35%), blaOXA-181 (n = 7; 35%) and blaNDM-5 (n = 6; 30%) genes were identified. C. freundii ST22 harboured blaNDM-5, blaOXA-48 and blaCTX-M-15 genes. Some E. coli isolates belonging to the high-risk clone ST410 were closely related (<20 SNPs) to isolates recovered in France from patients returning from Senegal, suggesting transnational spread. In addition, 5/6 carbapenemase-producing E. coli isolates possessed a four amino acid insertion in PBP3, conferring reduced susceptibility to aztreonam/avibactam and cefiderocol.

Conclusions: This study highlights the spread of NDM-5 and OXA-181 in Senegal, and reports the first co-occurrence of NDM-5 and OXA-48 in sub-Saharan Africa. The spread of CPE, especially in high-risk clones, underscores the urgent need for continued surveillance and targeted interventions.