Multidrug Resistance, Biofilm Formation, and Virulence of Escherichia coli Isolates from Commercial Meat and Vegetable Products.

Escherichia coli is an important food safety and public health concern because of its pathogenicity and potential for antimicrobial resistance. E. coli isolates as food contaminants and their antimicrobial resistance, biofilm-forming ability, and virulence genes were analyzed to identify the potential of E. coli in food as a major transmission route for antimicrobial resistance and infectious agents. Among the 709 samples of minced meat and fresh vegetable products tested, 18.6% were positive for E. coli. One hundred nine (29.2%) out of 383 E. coli isolates were resistant to 1 or more of the 25 tested antimicrobials. Among the isolates from minced pork, the highest rate of resistance was observed for tetracycline (52.8%), followed by ampicillin (41.6%). The highest resistance rates against tetracycline were coincident with the high amount of tetracycline sold for veterinary use. Because penicillin is the most frequently used antimicrobial in humans, with 4.52 defined daily doses per 1000 people per day, the high rate of resistance to ampicillin (41.6%) supported the potential risk of E. coli food contaminants. However, only 1.3% of the isolates possessed the virulence genes commonly involved in foodborne outbreaks of E. coli. Sixty-seven isolates (17.5%) were multidrug-resistant (MDR), and the highest MDR was observed against 14 antimicrobials. Most of the MDR E. coli isolates showed biofilm-forming ability. Therefore, these isolates will have additional protection from environmental stresses, including antimicrobials. Given the importance of E. coli to food safety and public health, our results on the prevalence of antimicrobial resistance and virulence factors provide useful information for risk management options to protect public health.