Antibiotic resistance mechanisms and global resistance patterns of Pseudomonas aeruginosa in microbial keratitis

Microbial keratitis (MK) is a rapid and devastating infection that can result reduced vision, with lack of treatment potentially resulting in stromal necrosis and even permanent vision loss. Pseudomonas aeruginosa is a common cause of MK and its rise in antibiotic resistance has made it increasingly difficult to treat. This review aims to provide a better understanding of the resistance mechanisms of P. aeruginosa and highlights major adaptations to combat fluoroquinolones, aminoglycosides, β-lactams and polymyxin antibiotics commonly used in MK, and addresses the global resistance profiles of P. aeruginosa keratitis. A narrative review was conducted using PubMed, Scopus, Web of Science, MEDLINE, and Google Scholar. Search terms included “Pseudomonas aeruginosa”, “microbial keratitis”, “antibiotic resistance”, antibiotic class-specific resistance terms, “surveillance studies”, and “regional resistance patterns” to consolidate current information of the various intrinsic, acquired and adaptive resistance mechanisms of P. aeruginosa conferred across fluoroquinolones, aminoglycosides, β-lactams and polymyxin along with resistance profile of keratitis isolates across continents. P. aeruginosa displays complex resistance mechanisms, including intrinsic efflux systems, reduced porin permeability, enzymatic drug inactivation, horizontal gene transfer, and target-site mutations, contributing to MDR in MK. Resistance patterns vary markedly by region, with higher resistance to fluoroquinolones, cephalosporins, and aminoglycosides reported in Asia, while Europe and North America showed lower rates. Australian isolates demonstrate heterogeneous resistance, retaining susceptibility to aminoglycosides. Future studies comparing resistance mechanisms and data of P. aeruginosa across regions will be essential to identify geographical variations, inform region-specific surveillance, guide targeted therapies to improve interventions of MK.