Monitoring and molecular characterization of multidrug resistant enteropathogenic E. coli in dairy calves and their environment

This study was performed to investigate the frequency and the distribution of antimicrobial resistance and resistant genes in enteropathogenic Escherichia coli (EPEC) isolated from both calves and their environment. Fecal samples (n=136) were collected from calves, besides 270 environmental samples for isolation and identification of EPEC. 50 E. coli isolates comprising 6 serogroupgs were recovered and tested against 12 antimicrobials comprising 4 different groups and 3 disinfectants with characterization of resistance genes. Results revealed that E. coli was isolated in the highest percentage from diarrheic calves (68.3%) followed by apparently healthy and environment (56.7 and 56.6 %, respectively). Six serogroups of E. coli were identified from diarrheic calves with the highest percentage of O26 (27.8 %) followed by O159 and O55 (16.7 and 16.6 %, respectively). The tested isolates showed high rates of resistance to tetracycline, ampicillin, and sulfamethoxazole-trimethoprim whereas the highest rates of susceptibility were found to enrofloxacin and neomycin. Meanwhile the highest bactericidal effect against E. coli isolates from calves and environment was exhibited by Virkon® S (80 % and 70 %, respectively) compared to 80 % and 50%, respectively for TH4+ and 60 and 70 %, respectively for iodine. E. coli isolates were found to include the following genes blaTEM, qacED1, dƒrA, tetA, and sul1. In conclusion, the high prevalence of multidrug resistant E. coli provided insights about the possibility of dairy calves to act as source of resistance genes in the environment that pose health risk for humans and animals.