Mobilization of an ICEclc-Like Element as a Potential Mechanism for the Spread of IMP-13 Carbapenemase in Pseudomonas aeruginosa

Carbapenem-resistant Pseudomonas aeruginosa is a global public health concern. IMP-13 is a carbapenemase that was described for the first time in 2001 but is often underestimated due to poor hydrolysis of carbapenems and a lack of molecular detection. The aim of this study was to characterize the genetic support of bla_IMP-13 in P. aeruginosa and to assess the ability of mobile genetic elements to disseminate this resistance. A retrospective analysis conducted between 2010 and 2020 revealed eight multiresistant P. aeruginosa isolates by their production of the carbapenemase IMP-13 in Bordeaux. Additionally, three of the studied isolates exhibited high-level resistance to imipenem and imipenem-relebactam that was linked to an insertion sequence in the oprD gene. Successful mating was achieved, and transconjugants and parental clinical isolate genomes were sequenced. All clinical isolates were found to be ST621 strains. The data revealed that bla_IMP-13 was carried on an Integrative and Conjugative Element (ICEclc-like) of 88,589 bp with a 62% GC content harboring 85 CDSs, and was inserted at the tRNA^Gly locus PA0729.1. The ICE was identical in the eight studied clinical isolates and in all the ST621 strains found in the databases. The conjugation rate was low, at approximately 10^-8 transconjugants per donor and ICE transfer appeared to mobilize some adjacent parental genes located immediately downstream of the ICE. In conclusion, these results suggest that even if the spread of bla_IMP-13 is mainly due to an epidemic ST621 clone, the mobilization of a bla_IMP-13-carrying ICEclc-like element is possible and should not be underestimated.