Contribution of Healthy Chickens to Antimicrobial-Resistant Escherichia coli Associated with Human Extraintestinal Infections in Egypt.

Abstract

Chickens are considered potential reservoirs for human extraintestinal infections with pathogenic Escherichia coli. However, information about genetic relatedness between E. coli from healthy chickens and human patients is still limited. In this study, clinical samples from patients with extraintestinal infections and healthy broiler chickens were collected from geographically related locations in Egypt during the 2nd half of 2015. The recovered isolates were tested for susceptibility against β-lactam antimicrobials and screened for the presence of extended-spectrum β-lactamases (ESBLs) and virulence genes; clonal and phylotypes were also determined. Forty-eight percent (48/100) and 31.3% (50/160) of human and chicken samples were positive for E. coli, respectively. Although only 4% (2/50) of the chicken isolates were resistant to the tested β-lactams, over 58% of human E. coli isolates (28/48) exhibited resistance to cefotaxime. For β-lactamases, 52.1%, 33.3%, 20.8%, and 6.25% of human E. coli were positive for blaCTX-M, blaTEM, blaOXA, and blaCMY, while blaTEM, blaOXA, and blaCMY were found in 32%, 4%, and 34% of chicken isolates, respectively. Low frequencies of virulence genes within human and chicken E. coli isolates were detected by PCR. The majority of E. coli isolates harboring β-lactam resistance genes from human and chicken sources belonged to phylogroup C and B1, respectively. Using pulsed-field gel electrophoresis (PFGE), some E. coli grouped based upon source; however, most clusters contained isolates from both humans and chickens. The above findings suggest that although no single clone appeared to be circulating among E. coli isolates from human and chicken, some shared characteristics exist among isolates from both sources. Increased study will aid to track the dissemination of β-lactam-resistant E. coli from healthy chickens to humans for implementation of effective intervention strategies.