blaCTX-M-15 carried by IncF-type plasmids is the dominant ESBL gene in Escherichia coli and Klebsiella pneumoniae at a hospital in Ghana

• We characterize the resistance phenotypes of 101 E. coli and K. pneumoniae isolates at a major teaching hospital in Ghana.
• All isolates with an ESBL phenotype carried a blaCTX-M gene, and CTX-M-15 is the predominant CTX-M enzyme.
• blaCTX-M-15 is mostly carried on IncFII plasmids in E. coli and IncFIIK in K. pneumoniae.
• This study reveals a polyclonal spread of blaCTX-M-15 among Enterobacteriaceae with an ESBL phenotype in Ghana.

Escherichia coli and Klebsiella pneumoniae producing extended-spectrum β-lactamases (ESBLs) are among the most multidrug-resistant pathogens in hospitals and are spreading worldwide. Horizontal gene transfer and spread of high-risk clones are involved in ESBL dissemination. Investigation of the resistance phenotypes of 101 consecutive clinical E. coli (n = 58) and K. pneumoniae (n = 43) isolated at the Komfo Anokye Teaching Hospital in Ghana over 3 months revealed 63 (62%) with an ESBL phenotype. All 63 had a blaCTX-M gene, and sequence analysis showed that 62 of these were blaCTX-M-15. blaCTX-M-15 was linked to ISEcp1 and orf477Δ in all isolates, and most isolates also carried blaTEM, aac(3)-II, aacA4cr, and/or blaOXA-30 genes on IncF plasmids. XbaI/pulsed-field electrophoresis showed heterogeneity among isolates of both species, suggesting that blaCTX-M-15 dissemination is caused by horizontal gene transfer rather than clonal spread of these species in Ghana.