Background: Escherichia coli  strains are the most commonly isolated bacteria in hospitals. The normally harmless commensal E. coli  can become a highly adapted pathogen, capable of causing various diseases both in healthy and immunocompromised individuals, by acquiring a combination of mobile genetic elements. Our aim was to characterize E. coli  strains from a hospital in western China to determine their virulence and antimicrobial resistance potential.
Methods: A total of 97 E. coli  clinical isolates were collected from the First Affiliated Hospital of Chengdu Medical College from 2015 to 2016. Microbiological methods, PCR, and antimicrobial susceptibility tests were used in this study.
Results: The frequency of occurrence of the virulence genes fimC, irp2, fimH, fyuA, lpfA, hlyA, sat , and cnf1  in the E. coli  isolates was 93.81, 92.78, 91.75, 84.54, 41.24, 32.99, 28.86, and 7.22%, respectively. Ninety-five (97.9%) isolates carried two or more different virulence genes. Of these, 44 (45.4%) isolates simultaneously harbored five virulence genes, 24 (24.7%) isolates harbored four virulence genes, and 17 (17.5%) isolates harbored six virulence genes. In addition, all E. coli isolates were multidrug resistant and had a high degree of antimicrobial resistance.
Conclusion: These results indicate a high frequency of occurrence and heterogeneity of virulence gene profiles among clinical multidrug resistant E. coli  isolates. Therefore, appropriate surveillance and control measures are essential to prevent the further spread of these isolates in hospitals.
Keywords: Escherichia coli , clinical isolates, virulence genes, antimicrobial resistance, MDR