High Prevalence of GES-5 Variant and Co-Expression of VIM-2 and GES-45 among Clinical Pseudomonas aeruginosa Strains in Tunisia

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) are a global health concern. The antimicrobial resistance, virulence, and molecular typing of 57 CRPA isolated from 43 patients who attended a specific Tunisian hospital from September 2018 to July 2019 were analyzed. All but one were multidrug-resistant CRPA, and 77% were difficult-to-treat-resistant (DTR) isolates. The blaVIM-2 gene was detected in four strains (6.9%), and among the 36 bla(GES)-positive CRPA (62%), the bla(GES-5) gene was the predominant variant (86%). Three strains co-harbored the bla(VIM-2) and bla(GES-45) genes, and seven CRPA carried the bla(SHV-2a) gene (14%). OprD alterations, including truncations by insertion sequences, were observed in 18 strains. Regarding the 46 class 1 integron-positive CRPA (81%), the bla(GES-5) gene was located in integron In717, while the bla(GES-29) and bla(GES-45) genes were found in two new integrons (In2122 and In4879), and the bla(VIM-2) gene was found in In1183 and the new integron In2142. Twenty-four PFGE patterns and thirteen sequence types (three new ones) were identified. The predominant serotype O:11 and exoU (81%) were mostly associated with ST235 and the new ST3385 clones. The seven bla(SHV-2a)-CRPA from different patients belonged to ST3385 and the same PFGE pattern. The bla(GES-5)- and bla(VIM-2) + bla(GES-45)-positive CRPA recovered mostly from ICU patients belonged to the high-risk clone ST235. Our results highlight the alarming prevalence of bla(GES-5)- and ST235-CRPA, the co-existence of bla(GES-45) and bla(VIM-2), and their location within integrons favoring their dissemination.