Pseudomonas aeruginosa epidemic high-risk clones and their association with horizontally-acquired β-lactamases: 2020 update

Abstract

Pseudomonas aeruginosa global clones associated with multidrug-resistant (MDR) and extensively drug-resistant (XDR) phenotypes, denominated high-risk clones, are a growing threat in hospitals worldwide. Here we provide a 2020 update on nosocomial MDR/XDR high-risk P. aeruginosa clones. According to their prevalence, global spread and association with MDR/XDR profiles and regarding extended-spectrum β-lactamases (ESBLs) and carbapenemases, the worldwide top 10 P. aeruginosa high-risk clones includes ST235, ST111, ST233, ST244, ST357, ST308, ST175, ST277, ST654 and ST298. ST235 is certainly the most relevant high-risk clone, showing a worldwide dissemination associated with over 60 different β-lactamase variants, including multiple carbapenemases from classes A and B. Moreover, ST235 shows a highly virulent phenotype associated with a high mortality rate, likely due to the production of the ExoU cytotoxin. ST111 and ST233 are also worldwide disseminated MDR/XDR clones, particularly linked to VIM-2 metallo-β-lactamase (MBL), whereas ST244 is a very prevalent clone not always associated with MDR/XDR profiles. ST357, ST308 and ST298 are also exoU+ and are therefore potentially associated with higher virulence. In contrast, ST175, prevalent in some European countries, shows a MDR/XDR phenotype frequently caused by specific chromosomal mutations and is associated with lower virulence. Finally, ST277 is highly prevalent in Brazil and is specifically associated with the SPM MBL. A deeper understanding of the underlying factors driving the success of high-risk clones, including the reported increased capacity for acquiring exogenous determinants, increased spontaneous mutation rates or greater ability to develop biofilms, is required to develop global strategies to combat them.

Keywords: Carbapenemase; Extended-spectrum β-lactamase; Extensively drug-resistant; High-risk clone; Multidrug-resistant; Pseudomonas aeruginosa.