Antibiotic Resistance in Pseudomonas Aeruginosa: Resistance Mechanisms, Clinical Significance, and Current Challenges

Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium associated with healthcare-associated infections and difficult-to-treat infections in vulnerable patients. Its clinical importance is driven by intrinsic resistance, the ability to acquire additional resistance determinants, multiple virulence factors, and biofilm formation. This review summarises major resistance mechanisms, including reduced outer-membrane permeability, efflux pumps, chromosomal AmpC beta-lactamase, acquired beta-lactamases, target mutations, and biofilm-associated tolerance. It also outlines the implications of carbapenem resistance, laboratory susceptibility testing, antimicrobial stewardship, and infection-prevention measures. Recent literature highlights the continuing global concern about multidrug-resistant P. aeruginosa and the need for local surveillance and susceptibility-guided therapy. This manuscript is a narrative review; it does not report a new clinical isolate collection or original experimental results. Therefore, no unverified local resistance percentages or patient-outcome estimates are presented.