A rare class A carbapenemase FRI-11 in Enterobacter clinical strain

We found a carbapenem-resistant Enterobacter clinical strain which was susceptible to cefotaxime and ceftazidime. This unusual susceptibility profile promoted the investigation. This strain had bla(FRI-11), a rare carbapenemase-encoding gene, on a 93,864-bp plasmid containing two replicons of IncFII(pECLA) and IncFIA(HI1). FRI-11, FRI-2, FRI-3, FRI-4, FRI-6, FRI-7, and FRI-9 belong to the same group of FRI beta-lactamases based on the amino acid sequence similarity and their encoding genes are carried by plasmids containing an IncFII(pECLA) replicon. Awareness should be raised towards FRI carbapenemases that are plasmid-encoded and confer an unusual carbapenem-resistant but 3rd-generation-cephalosporin-susceptible resistance profile.

Automated summary

We identified a clinical strain of Enterobacter that was resistant to carbapenems but susceptible to cefotaxime and ceftazidime. The presence of the rare carbapenemase-encoding gene bla(FRI-11) on a plasmid containing two replicons, IncFII(pECLA) and IncFIA(HI1), sparked further investigation. The FRI carbapenemases, including FRI-11, FRI-2, FRI-3, FRI-4, FRI-6, FRI-7, and FRI-9, belong to the same group based on amino acid sequence similarity and are carried by plasmids containing an IncFII(pECLA) replicon. Awareness should be raised regarding plasmid-encoded FRI carbapenemases that confer an unusual carbapenem-resistant but 3rd-generation-cephalosporin-susceptible resistance profile.