Virulence Factors in Enterococci from Partridges (Alectoris rufa) Representing a Food Safety Problem

Abstract

Forty-three Enterococcus isolates recovered from fecal samples of partridges, during the partridge hunting season, were studied for gelatinase and β-hemolysis activities. The presence of fsr-gelE genes and the cyl operon was studied by polymerase chain reaction and correlated with gelatinase and β-hemolysis production, respectively. In addition, genes encoding additional virulence factors (cpd, hyl, agg, esp, and ace) was also analyzed in all enterococci. Most of our Enterococcus faecalis isolates showed gelatinase activity (10 of 15 isolates), and this activity was not present in the other enterococcal species. All enterococci that showed gelatinase activity harbored the gelE and fsr genes. A large proportion of our isolates harbored genes of the cyl operon (19 of 43 isolates), although only 1 isolate contained the five cyl tested genes (E. faecalis), being the only one that expressed β-hemolysis. From the additional virulence factors (cpd, hyl, agg, esp, and ace), at least one virulence gene was detected in 13 of the 15 E. faecalis isolates, with cpd being the most frequently detected gene (9 isolates), followed by agg (5 isolates) and ace (4 isolates) genes. These virulence genes were not detected in the other enterococcal species with the exception of one E. faecium and E. casseliflavus isolate that harbored the hyl and cpd genes, respectively. Moreover, the esp gene was not detected in any of our isolates. In conclusion, this study showed the presence of virulence factors in enterococci of partridges and the possible transmission to humans through the food chain.