MOLECULAR DETERMINANTS OF ANTIMICROBIAL RESISTANCE AND VIRULENCE IN CLINICAL PSEUDOMONAS AERUGINOSA ISOLATES IN NIGERIA

Pseudomonas aeruginosa remains one of the leading causes of healthcare-associated infections and is recognized for its remarkable ability to acquire antimicrobial resistance while maintaining multiple virulence traits that contribute to persistent and difficult-to-treat infections. In Nigeria, increasing reports of multidrug-resistant (MDR) and carbapenem-resistant P. aeruginosa from tertiary healthcare facilities have raised significant concerns regarding treatment outcomes and infection control. This review synthesizes current evidence on the molecular determinants of antimicrobial resistance and virulence among clinical P. aeruginosa isolates in Nigeria, with emphasis on epidemiology, resistance patterns, resistance genes, virulence determinants, and existing knowledge gaps. Relevant literature published between 2021 and 2025 was retrieved from PubMed, Scopus, Web of Science, Google Scholar, and African Journals Online (AJOL). Available evidence indicates increasing resistance to β-lactams, fluoroquinolones, aminoglycosides, and carbapenems, driven by intrinsic, acquired, and adaptive resistance mechanisms, including carbapenemase genes, efflux pump overexpression, AmpC hyperproduction, and OprD porin alterations. Virulence determinants, particularly biofilm formation, quorum-sensing systems, and genes such as lasB, toxA, exoS, and exoU, remain widely distributed and frequently coexist with antimicrobial resistance determinants, enhancing bacterial persistence and pathogenic potential. However, molecular epidemiological data remain fragmented, with most studies originating from a limited number of tertiary hospitals and few incorporating whole-genome sequencing or comprehensive genomic surveillance. Strengthening nationwide molecular surveillance, integrating genomic epidemiology into antimicrobial resistance monitoring, standardizing laboratory methodologies, and reinforcing antimicrobial stewardship programmes are essential for improving patient management, guiding empirical therapy, and limiting the dissemination of high-risk P. aeruginosa clones in Nigeria.