Microbiological and molecular detection of virulent and antibiotic-resistant Escherichia coli in retail chickens from the metropolitan region of Belém, Pará, Brazil

This study aimed to investigate the occurrence of Escherichia coli isolates in retail poultry from open-air markets and supermarkets in the metropolitan region of Belém, State of Pará, Brazil, and to characterize their antimicrobial resistance profiles and the presence of selected virulence-associated genes. In this study, 14 chicken samples were collected from open-air markets (n=7) and supermarkets (n=7) and subjected to microbiological analysis and multiplex PCR to detect the iss and tsh virulence genes. Following strain identification, antimicrobial susceptibility testing (AST) was performed to evaluate the effects of five antimicrobial agents (amoxicillin, cephalexin, doxycycline, enrofloxacin, and sulfamethoxazole). Microbiological analysis showed that E. coli was detected in 71.42% (10/14) of the chicken carcasses. In contrast, PCR detected at least one virulence gene in all positive samples, with the iss gene being identified in 100% and the tsh gene in 85.7% (12/14) Among the 25 E. coli isolates obtained from the organs of chickens from both retail sources, 76% were resistant to enrofloxacin (76%), sulfamethoxazole (40%), doxycycline (36%), amoxicillin (32%), and cephalexin (28%). These findings indicate that retail broilers may harbor E. coli strains carrying virulence genes and exhibiting multidrug resistance, suggesting a potential public health concern for food safety.