Virulence and antimicrobial resistance mechanisms in Pseudomonas aeruginosa in dogs and cats: a review

Pseudomonas aeruginosa is an important opportunistic pathogen in companion animal medicine, because it is associated with chronic, recurrent, and treatment-refractory infections. In dogs and cats, it has been identified in a range of clinical conditions, most notably otitis externa (OE), but also urinary tract, ocular, skin and soft tissue, and less frequently, respiratory infections, usually as opportunistic secondary pathogens. The pathogenic success of P. aeruginosa is related to its broad virulence repertoire, including adhesion factors, extracellular enzymes, exotoxins, secretion systems, quorum sensing regulation, and a marked capacity for biofilm formation. These virulence factors contribute to tissue damage, persistence, and treatment failure. In parallel, its intrinsic resistance and ability to acquire additional resistance determinants frequently result in multidrug-resistant (MDR) phenotypes, while the detection of internationally recognises high-risk clones in companion animals raises concern from both clinical and One Health perspectives. This review summarises current knowledge on the epidemiology, clinical manifestations, virulence traits, biofilm-associated persistence, antimicrobial resistance, and molecular epidemiology of P. aeruginosa in companion animals. Emphasis is placed on the diagnostic and therapeutic challenges posed by chronic and resistant infections, as well as on the growing pertinence of genomic tools for surveillance and characterisation of high-risk lineages. Overall, this review aims to better define the role of companion animals in the maintenance and dissemination of clinically important lineages.