Phenotypic and molecular analysis of Pseudomonas aeruginosa virulence and association with antibiotic resistance in Egypt.

Introduction: Pseudomonas aeruginosa is a common nosocomial pathogen with multidrug resistance (MDR) and virulence factors (VFs). This study assessed the VFs and their associations with MDR and non-MDR isolates.

Methodology: One hundred clinical isolates were analyzed for 12 VFs, encoding genes, and phenotypic traits. Antibiotic resistance patterns and correlations between VFs and MDR were investigated.

Results: Aztreonam showed the highest resistance rate among MDR (94.7%) and ceftazidime showed the highest resistance rate among non-MDR isolates (44.2%). Carbapenems demonstrated the greatest susceptibility. VF positivity rates included 91% for algD, 90% for lasB, 86% for toxA, 82% for exoS, 19% for exoU, 78% for aprA, 75% for plcH, 94% for pigment production, 93% for biofilm formation, 72% for hemolysin, 65% for lipase, and 36% for DNase. Strong biofilm formation correlated with algD and lasB (93%). Pigment production was linked with lasB and toxA (94%). Strong biofilm formation was significantly higher in MDR isolates and resistant strains, than non-MDR isolates. No significant differences in VFs were observed between susceptible and resistant strains for lasB, algD, toxA, plcH, exoU, or general biofilm production; except for strong biofilm formation. Certain VFs correlated with susceptible isolates: exoS with tobramycin, aprA with aztreonam and piperacillin-tazobactam, pigment production with imipenem, DNase with aztreonam and norfloxacin, and lipase with tobramycin and ceftazidime.

Conclusions: P. aeruginosa isolates displayed diverse VFs, biofilm-forming abilities, and MDR profiles; with strong biofilm formation closely linked to MDR. Targeting biofilm-related genes (algD, lasB) could offer effective therapeutic interventions, helping mitigate MDR infections and improve clinical outcomes.