Molecular characterization of OXA-198 carbapenemase producing Pseudomonas aeruginosa clinical isolates [PublishAheadOfPrint]

Carbapenemase-producing Pseudomonadaceae have increasingly been reported worldwide, with an ever-increasing heterogeneity of carbapenem resistance mechanisms depending on the bacterial species and its geographical location. OXA-198 is a plasmid-encoded class D β-lactamase involved in carbapenem-resistance in one Pseudomonas aeruginosa isolate from Belgium. In the setting of a multicentre survey of carbapenem-resistance in P. aeruginosa in Belgian hospitals in 2013, three additional OXA-198 producing P. aeruginosa originating from patients hospitalized at one hospital were detected. To reveal the molecular mechanism underlying the reduced susceptibility to carbapenems, MICs, whole genome sequencing (WGS) and PCR reactions to confirm the genetic organization were performed. The plasmid harboring bla_OXA-198 gene was characterized alongside with the genetic relatedness of the four P. aeruginosa isolates. The bla_OXA-198 gene was harbored on a class 1 integron carried itself by a ca. 49-kb IncP-type plasmid proposed as IncP11. The same plasmid was present in all four P. aeruginosa isolates. MLST typing revealed that they all belonged to ST-446 and SNP analysis revealed only a few differences between these isolates. This report describes the structure of a 49-kb plasmid harbouring the bla_OXA-198 gene and the first description of OXA-198 producing P. aeruginosa isolates associated with a hospital-associated cluster episode.

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