Novel allelic variants of bla carried on IncN and IncC plasmids isolated from clinical cases in Argentina: In vivo emergence of bla.

OBJECTIVE

The OXA-48-like enzymes have the capacity to hydrolyse carbapenems and are members of class D β-lactamases that are primarily detected in Enterobacterales. The allelic variant bla, which has low hydrolytic activity towards carbapenems, was detected in Argentina in 2011 and has spread successfully since then, giving sporadic origin to novel local variants. The aim of this study was to analyse the phenotypic profile and dissemination strategies of two novel OXA enzymes, bla and bla, located in Escherichia coli M17224 and Klebsiella pneumoniae M21014, respectively, isolated from two paediatric patients.

METHODS

Minimum inhibitory concentration measurements were performed to determine the phenotypic profile of the clinical isolates, transconjugants and transformant cells. Biparental conjugation, PCR, Sanger and whole-genome sequencing were performed to determine the complete genetic characteristics of the plasmids.

RESULTS

Both isolates were found to be resistant to carbapenems and susceptible to ceftriaxone. bla was located on a 69-kb IncN plasmid, while bla was found on a 175-Kb IncC plasmid, both transferable by biparental conjugation. The close genetic environment of the bla genes suggests a common origin likely involving mobile genetic elements. Finally, the clinical case of M21014 revealed that the patient had previous infections with two genetically related K. pneumoniae ST6838 that carried bla on an IncC plasmid with equal size and genetic hallmarks to that of M21014, providing strong evidence for the intra-patient emergence of bla CONCLUSIONS: This research underscores the need for ongoing surveillance and integral studies to understand the emergence, biochemistry and dissemination capacity of OXA enzymes with the overarching aim to halt their spread.