Biofilm Formation Potential and Virulence Determinants of Pseudomonas aeruginosa Isolates from Chronic Wound Infections in Calabar, Cross River State

Chronic wound infections are a significant burden in clinical settings, and Pseudomonas aeruginosa is frequently implicated as a persistent and treatment-recalcitrant pathogen due to its robust biofilm-forming capacity and diverse virulence mechanisms. This study characterized biofilm formation and virulence determinants of P. aeruginosa isolates from chronic wound infections at the University of Calabar Teaching Hospital, Cross River State, South South Nigeria. Sixty-five confirmed P. aeruginosa isolates from diabetic foot ulcers, pressure sores, and post-surgical wounds were analyzed. Quantitative biofilm formation was assessed using the crystal violet microplate assay. Virulence genes including lasB (elastase), aprA (alkaline protease), algD (alginate), toxA (exotoxin A), and rhlAB (rhamnolipid) were detected by PCR. Efflux pump overexpression and the MexAB-OprM system were investigated as contributing resistance mechanisms. Results showed strong biofilm formation in 72.3 percent of isolates. All five virulence genes were detected in 58.5 percent of isolates. Strong biofilm producers showed significantly higher rates of multidrug resistance and virulence gene co-carriage. MexAB-OprM efflux overexpression was confirmed in 66.2 percent of MDR isolates. Correlation analysis revealed that high biofilm formation was predictive of treatment failure outcomes as documented in patient records. These findings highlight the compounding effect of biofilm formation and virulence factor expression on chronicity of wound infections and inform the need for anti-biofilm therapeutic strategies. Keywords: Pseudomonas aeruginosa, biofilm, virulence genes, chronic wounds, Calabar.