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.