Molecular detection of ExoU and ExoS virulence genes among clinical isolates of P. aeruginosa recovered from patients attending a private tertiary hospital in southwestern Nigeria

Background: Pseudomonas aeruginosa is a notorious opportunistic pathogen associated with severe nosocomial infections. This study aimed to investigate the prevalence and distribution of ExoU and ExoS virulence genes among clinical isolates of P. aeruginosa in patients attending a private tertiary hospital in southwestern Nigeria. Methods: A total of fifty (50) non-duplicate clinical isolates of P. aeruginosa recovered from various clinical specimens were analyzed using Polymerase Chain Reaction (PCR) to detect the presence of ExoU and ExoS virulence genes. Statistical analysis was carried out with SPSS – Version 22.0. P-value <0.05 was considered to be statistically significant. Results: Among the 50 samples examined, 47 (94%) showed detectable presence of ExoU and/or ExoS genes, while only 3 (6%) showed no detectable presence. The number of samples with detectable ExoU and/or ExoS genes was significantly higher (P=0.01, χ² = 45.92) than those without detectable ExoU and/or ExoS genes highlighting the widespread occurrence of these virulence factors. The ExoU gene was detected in 36 (72%) isolates, while the ExoS gene was detected in 40 (80%) isolates. The difference was not statistically significant (P=0.170, χ² = 2.313). There is a statistically significant association (P=0.01, χ² = 61.985) between gene presence and sample type. ExoU and ExoS genes were predominantly associated with ear swabs. Conclusion: This study contributes to our understanding of molecular epidemiology and pathogenesis of P. aeruginosa in southwestern Nigeria and underscores the importance of considering infection site when assessing virulence gene prevalence. Further research is warranted to validate and expand upon these findings.