Antimicrobial Resistance Profiles and Clonal Relationship among Non-ESBL Avian Pathogenic Escherichia coli Isolates and ESBL Producing E. coli Isolates from Human Urinary Tract Infections

We aimed to investigate antimicrobial resistance and clonal relationships among poultry Escherichia coli isolates from different broiler farms and their relationships with Extended-Spectrum Beta-Lactamase (ESBL) producing urinary pathogenic E. coli (UPEC) isolates from the same geographical area.

Twenty four E. coli isolates from six broiler farms with colibacillosis and 97 ESBL producing human UPEC isolates were investigated for resistance to critically important antimicrobials in human medicine in Shiraz, central Iran in 2015-16. In addition, clonal relationships of these isolates were investigated with Pulse Field Gel Electrophoresis (PFGE).

As expected, cephalosporins and imipenem resistance were significantly higher in ESBL producing human E. coli isolates in comparison with non-ESBL avian pathogenic E. coli (APEC) isolates. In addition, significantly higher percentages of gentamycin and trimethoprim-sulfamethoxazole resistance were seen in human isolates. In contrast, nitrofurantoin resistance was significantly higher in APEC isolates. Based on PFGE patterns, five clusters were identified in APEC isolates. Isolates from each farm were closely related to each other by PFGE patterns. However, different PFGE restriction profiles were seen among the E. coli isolates from different broiler farms. Comparison of PFGE patterns among APEC and UPEC isolates showed two closely related PFGE patterns.

There were clonally related E. coli isolates caused the outbreaks of colibacillosis within broiler farms. Some of these isolates had closely related PFGE patterns with human UPEC isolates which suggest avian pathogenic E. coli strains as a potential zoonosis.