Outer membrane vesicles in Pseudomonas aeruginosa pathogenesis: a systematic review of virulence dissemination, immune modulation, and antimicrobial resistance, with perspectives for veterinary and one health practice.
Sophian Alfi A
Pseudomonas aeruginosa is an opportunistic pathogen recognised for its intrinsic and acquired antibiotic resistance, its capacity to establish chronic infections in cystic fibrosis (CF) airways, and its clinical importance in immunocompromised human and animal hosts. While its extensive secretome has been intensively studied, a mechanistically distinct dissemination strategy has emerged: the constitutive production of outer membrane vesicles (OMVs) that concentrate, protect, and deliver virulence cargo to host cells beyond direct bacterial contact. This systematic review evaluates the molecular mechanisms, biological consequences, antimicrobial resistance implications, and therapeutic prospects associated with OMV-mediated virulence in P. aeruginosa infection, and additionally considers the veterinary and One Health relevance of this evidence base. A systematic search of PubMed/MEDLINE, Scopus, Web of Science, and EMBASE was conducted from database inception to January 2025 following PRISMA 2020 guidelines. Studies investigating OMV production, cargo characterisation, or biological activity in the context of P. aeruginosa infection were eligible. Risk of bias was assessed using the ToxRTool (in vitro) and SYRCLE tool (in vivo). Inter-rater agreement was quantified by Cohen's kappa (kappa = 0.82). Fifty-eight studies (predominantly in vitro and murine models) met the inclusion criteria. P. aeruginosa OMVs (50-250 nm) carry biologically active type III secretion effectors (ExoS, ExoU), elastase (LasB), alkaline protease (AprA), pyocyanin, quorum-sensing autoinducers (3-oxo-C12-HSL), Hcp1, siderophores, and beta-lactamase enzymes including VIM and OXA-type carbapenemases. OMV-packaged beta-lactamases were shown, principally in co-culture experiments, to confer transferable resistance by degrading beta-lactam antibiotics in the extracellular milieu, shielding susceptible bystander bacteria. OMVs drive biofilm maturation, suppress CF airway innate immunity, and induce TLR4-mediated hyperinflammation. OMV output was consistently increased under antibiotic selection pressure, in the CF mucus environment, and during quorum-sensing activation, although the magnitude of increase varied considerably across experimental conditions and should be interpreted qualitatively rather than as directly comparable pooled estimates. Therapeutic strategies targeting OMV biogenesis, cargo neutralisation, and OMV-based vaccine platforms are evaluated, and remain at a predominantly preclinical stage of development. P. aeruginosa OMVs constitute a versatile virulence amplification platform that contributes to tissue destruction, immune evasion, biofilm consolidation, and antibiotic resistance dissemination. Disrupting this multi-functional delivery system represents a promising, though still largely preclinical, antibiotic-independent therapeutic direction for managing refractory P. aeruginosa infections, particularly in CF and critical care settings. Extension of this evidence base to animal-associated P. aeruginosa infections and One Health surveillance is identified as an important priority for future research.