Molecular Characterization of OXA-198 Carbapenemase-Producing Pseudomonas Aeruginosa Clinical Isolates

Carbapenemase-producing have increasingly been reported worldwide, with an ever-increasing heterogeneity of carbapenem resistance mechanisms, depending on the bacterial species and the geographical location. OXA-198 is a plasmid-encoded class D β-lactamase involved in carbapenem resistance in one isolate from Belgium. In the setting of a multicenter survey of carbapenem resistance in strains in Belgian hospitals in 2013, three additional OXA-198-producing isolates originating from patients hospitalized in one hospital were detected. To reveal the molecular mechanism underlying the reduced susceptibility to carbapenems, MIC determinations, whole-genome sequencing, and PCR analyses to confirm the genetic organization were performed. The plasmid harboring the gene was characterized, along with the genetic relatedness of the four isolates. The gene was harbored on a class 1 integron carried by an ∼49-kb IncP-type plasmid proposed as IncP-11. The same plasmid was present in all four isolates. Multilocus sequence typing revealed that the isolates all belonged to sequence type 446, and single-nucleotide polymorphism analysis revealed only a few differences between the isolates. This report describes the structure of a 49-kb plasmid harboring the gene and presents the first description of OXA-198-producing isolates associated with a hospital-associated cluster episode.