Investigation of Antibiotic Resistance Patterns and the Prevalence of Virulence Genes in the Clinical Strains of Carbapenem-Resistant <i>Escherichia coli</i>

Background and aims: The emergence of resistance to antibiotics in Escherichia coli has raised significant concerns in the medical community. This study evaluated the antibiotic resistance pattern and prevalence of virulence genes (pap, fimA, and aer) in carbapenem-resistant E. coli clinical isolates. Methods: A total of 96 E. coli isolates were collected from clinical samples from various hospital departments in Isfahan. The isolates were confirmed using biochemical and molecular tests. Antibiotic susceptibility patterns were determined based on the CLSI guidelines. The presence of virulence genes underwent investigation. Results: Among the isolates, 61% were obtained from male patients, and 39% were from female patients. The highest frequency was observed in the age groups of 41–50, 51–60, and 81–90 years old. The majority of antibiotic-resistant isolates (41%), multidrug-resistant (MDR) isolates (43.3%), and carbapenem-resistant isolates (41.7%) were collected from the emergency department (41%). The isolates showed the highest resistance to ampicillin (92%), while they exhibited the highest sensitivity to amikacin (96%). The MDR isolates were most resistant to ampicillin (93%), cotrimoxazole (88%), cefixime (80%), cefotaxime (67%), and ceftriaxone (50%). In general, 12 carbapenem-resistant isolates were confirmed to carry the OXA-48 gene, among which 100% harbored the aer gene and 75% had the pap gene, whereas none overcame the fimA gene. Conclusion: The highest rates of antibiotic resistance were in the emergency department, and urinary tract infections were the most common carbapenem-resistant infections. The high prevalence of virulence genes (aer and pap) should also be considered by the medical community to control strains carrying these genes.