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

Abstract

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 blaGES-positive CRPA (62%), the blaGES-5 gene was the predominant variant (86%). Three strains co-harbored the blaVIM-2 and blaGES-45 genes, and seven CRPA carried the blaSHV-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 blaGES-5 gene was located in integron In717, while the blaGES-29 and blaGES-45 genes were found in two new integrons (In2122 and In4879), and the blaVIM-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 blaSHV-2a-CRPA from different patients belonged to ST3385 and the same PFGE pattern. The blaGES-5- and blaVIM-2 + blaGES-45-positive CRPA recovered mostly from ICU patients belonged to the high-risk clone ST235. Our results highlight the alarming prevalence of blaGES-5- and ST235-CRPA, the co-existence of blaGES-45 and blaVIM-2, and their location within integrons favoring their dissemination.

Molecular characterization of Pseudomonas aeruginosa from diabetic foot infections in Tunisia

“…The spread of antimicrobial resistance genes through integrons is a growing problem in DFIs [78, 79]. In our study, the ST235-MDR Ps1311 strain harboured the In51 class 1 integron with the cassette gene arrangement aadA6-orfD, linked with resistance to aminoglycosides, and previously identified among P. aeruginosa isolated from clinical settings [16, 33, 67, 80, 81]. Class 1 integrons are potential threat to the emergence of MDR strains in clinical P. aeruginosa isolates [82, 83].…”

“…Class 1 integrons are potential threat to the emergence of MDR strains in clinical P. aeruginosa isolates [82, 83]. Moreover, it is frequently associated with the high-risk clone ST235 as demonstrated in other previous studies of our group [33, 80, 84].…”

“…Among the diversity of STs found in this work, the high-risk clone ST235 was encountered in two strains. ST235 has been largely reported in different other infections such as in wound infections and in burn patients [70–72] and has been associated with fatal patient outcomes [33, 73–76]. However, to the best of our knowledge, ST235 has not been previously described in DFIs, highlighting the presence and subsequent dissemination of this clone in this type of infections.…”

“…The clonal relationship among the P. aeruginosa recovered isolates was determined by pulsed-field gel electrophoresis (PFGE) with Spe I restriction enzyme [33]. DNA profiles were analysed by the GelJ software 2.3 (UPGMA algorithm; Dice coefficient) [34].…”