Purpose: Our goal was to examine the microbiological quality of imported vegetables available in Canada.
Methods: Fresh imported produce (61 herb, 20 spinach, and 25 leafy greens) from five cities across Canada were microbiologically tested for quality (total bacterial count, coliforms, enterococci, Escherichia coli) and the presence of E. coli O157:H7 and Salmonella spp. Recovered enterococci were screened for antimicrobial resistance (AMR). The mobility of R-plasmids in enterococci was examined through transformation into Staphylococcus aureus.
Results: No pathogenic bacteria were recovered. With the exception of one sample, total microbial loads were >4 log CFU/g. Overall, coliforms were detected in 45.3% of samples, enterococci in 55.7%, and E. coli in 3.8%. Produce originating from Columbia had the highest recovery of E. coli (11.1%). Of enterococci recovered, 33.9% were Enterococcus faecium and 16.4% were En. faecalis; in Mexican produce, these were recovered at a rate of 44.3% and 9.8%, respectively. Enterococci were observed to be resistant to antimicrobials used in animal feed, including bacitracin, tetracycline, and penicillin. Additionally, reduced susceptibility to clinically relevant antimicrobials (chloramphenicol, kanamycin, synercid) was also observed. En. faecalis R-plasmids possessing a tet gene were transferrable to S. aureus through transformation, but not conjugation.
Significance: Overall, a lack of pathogens and the observed incidence and levels of indicator organisms show imported produce to be of acceptable quality. However, the transmission of clinically relevant antimicrobials via imported produce warrant further investigation to ascertain risk to the consuming public.