Evaluation of the extent of spreading of virulence factors and antibiotic resistance in Enterococci isolated from fermented and unfermented foods

Abstract

The aim of this work was to evaluate the impact of fermentation processes on the incidence of virulence and antibiotic resistance determinants in Enterococcus strains from food origin (milk, fermented milk, cheese, fresh meat and fermented meat) with regards to potential pathogenicity. A total of 167 enterococcal strains were used in this study. Of those, 2 were reference strains, and 165 were isolated and identified by molecular methods and screened for virulence factors including ace, agg, ccf, cpd, esp, efaAfm and gelE as well as resistance against ten antibiotics. Enterococcal isolates were identified as Enterococcus faecium (54), Enterococcus faecalis (86), Enterococcus casseliflavus (10) and other Enterococcus spp. (15). Only 3 out of 88 fermented food isolates were free from virulence determinants while approximately 16 % of strains isolated from unfermented foods were free from virulence determinants. Unusually, the Ace gene was detected in E. faecium, especially in fermented foods. In contrast, antibiotic resistance in enterococci was not potentiated by the fermentation process. This study has revealed the important role that may be played by fermentation processes in virulence gene incidence and the potential of such processes to disseminate these traits throughout the enterococci food chain.