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 bla VIM-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.