Abstract: Pseudomonas aeruginosa, a widespread ubiquitous opportunistic pathogen, is a leading cause of opportunistic infections in humans and is associated with an ever-widening spectrum of infections and multidrug-resistance phenomena. The evolution and spread of antibiotic resistant pathogens has become a threat to public health and strongly affects the effectiveness of most currently available antimicrobial agents, compromising the treatment of infections. This review will explore how its physiology, social behaviour and genome plasticity are shaped towards competitiveness and improved fitness. When facing a stressor, P. aeruginosa can adapt by different mechanisms, such as phenotypic switching, which might result in a worsening clinical outcome (e.g. increased antimicrobial resistances). Such phenotypic flexibility renders P. aeruginosa a feared nosocomial pathogen that continues to be problematic from a clinical perspective.

Keywords: Pseudomonas aeruginosa; Pathogen; Virulence; Multidrug resistance; Phenotypic switching