Histopathological changes induced in an animal model by potentially pathogenic Enterococcus faecalis strains recovered from ready-to-eat food outlets in Osun State, Nigeria

Enterococci have been implicated as an emerging important cause of several diseases and multiple antibiotic resistance. However, there is little information about the prevalence of pathogenic and/or antibiotic-resistant Enterococcus faecalis in ready-to-eat foods in Nigeria. Here we report the pathogenic potential of three selected antibiotic-resistant E. faecalis strains isolated from food canteens and food outlets with different virulence determinant genes, including EFC 12 (with gel(+), esp(+), cylA(+), and asa1(+)), EFT 148 (with gel(+), ace(+), and asa1(+)), and EFS 18 (with esp(+) and cylA(+)) in an animal model. Enterococcemia, hematological parameters, and histopathological changes in organ tissues were examined in experimental animals. The results showed differences in enterococcemia and hematological parameters between the control group and experimental animal group. Enterococcemia was observed for 7 days, and the animal group infected with EFC 12 showed the highest growth rate, followed by EFT 148, with the lowest growth rate seen in the EFS 18-infected group. White blood cell count, packed cell volume, and platelets were significantly reduced (P<0.05) in the experimental animals compared with the controls. White blood cells decreased drastically during the study period in rats challenged with EFC 12 (from 7,800 to 6,120 per mm(3)) but levels remained higher in the control group (from 9,228 to 9,306 per mm(3)). Histopathological changes included areas of pronounced hemorrhage, necrosis, and distortion in liver tissues, which were more marked in rats infected with EFC 12, followed by EFT 148, then EFS 18. The results of this study suggest the presence of potentially pathogenic E. faecalis strains in food canteens and food outlets; hence, there is a need for strict adherence to good hygiene practices in the study area owing to the epidemiological significance of foods.