Prevalence, virulence factors, and antimicrobial resistance profiles of Shiga toxin-producing Escherichia coli isolated from broiler chickens in Egypt

Pathogenic Escherichia coli is one of the world’s most important zoonotic foodborne pathogens and poses a serious threat to public health. We examined the prevalence, virulence genes, and antibiotic resistance profile of Shiga toxin (Stx)-producing E. coli (STEC) isolated from broiler chickens in the Kafr El-Sheikh governorate, Egypt. A total of 410 samples (230 cloacal swabs, 180 internal organs) were collected to isolate E. coli. A total of 29 (7.07%) E. coli isolates were recovered and identified, and 18 of them harbored Stx genes (stx). Out of 18 isolates, five (17.24%) carried the stx1 gene, five (17.24%) carried the stx2 gene, four (13.79%) carried both stx1 and stx2 genes, and four (13.79%) carried stx1, stx2, and eaeA genes. Overall, complete antibiotic resistance was observed against amoxicillin, ampicillin, cefpodoxime, and cefoperazone; high resistance was observed against ampicillin/sulbactam, nalidixic acid, cefuroxime, aztreonam, ciprofloxacin, ceftriaxone, chloramphenicol, sulfamethoxazole/ trimethoprim, and ceftazidime; moderate resistance against gentamicin; low resistance against cefoxitin; lower resistance was detected against norfloxacin, cefotetan, and amikacin; and the lowest resistance against imipenem. All E. coli isolates demonstrated multidrug resistance against at least four antibiotic classes. Out of 29 E. coli isolates, STEC accounted for 18 isolates, of which the O78, O26:H11, O128:H2, O1:H7, O119:H6, and O91:H21 serogroups were predominant. All E. coli isolates were multidrug resistant and therefore pose a potential public health concern as these virulent, resistant strains may spread to humans. Thus, high levels of hygiene and biosecurity are required by chicken handlers to decrease the danger of infection spreading to humans.