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

Olawale AK, David OM, Oluyege AO, Osuntoyinbo RT, Laleye SA, Famurewa O - Infect Drug Resist (2015)

Bottom Line: The results showed differences in enterococcemia and hematological parameters between the control group and experimental animal group.White blood cell count, packed cell volume, and platelets were significantly reduced (P<0.05) in the experimental animals compared with the controls.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Sciences, Osun State Polytechnic, Iree, Nigeria ; Department of Microbiology, University of Ado-Ekiti, Ado-Ekiti, Nigeria.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus

Pathogenic effects of Enterococcus faecalis strains on experimental animals (magnification 400×). (A) Liver tissue of albino rat (control group) showing normal tissue appearance. (B) Liver tissue of albino rat, fed with EFC 12 (having four virulence genes gel+, esp+, cylA+, and asa1+) showing pronounced renal corpuscles and areas of inflammatory changes (arrow). (C) Liver tissue of albino rat fed with EFT 148 (having three virulence genes gel+, ace+, and asa1+) showing necrosis of hepatic cells with pyknotic nuclei, disorganization of hepatic laminae, and dilation of sinusoids (arrow). (D) Liver tissue of albino rats, fed strain of E. faecalis strain EFS 18 (having two virulence genes, ie, gel−, esp+, and cylA+) showing well preserved renal corpuscles and less pronounced areas of inflammatory changes (arrow).
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f2-idr-8-181: Pathogenic effects of Enterococcus faecalis strains on experimental animals (magnification 400×). (A) Liver tissue of albino rat (control group) showing normal tissue appearance. (B) Liver tissue of albino rat, fed with EFC 12 (having four virulence genes gel+, esp+, cylA+, and asa1+) showing pronounced renal corpuscles and areas of inflammatory changes (arrow). (C) Liver tissue of albino rat fed with EFT 148 (having three virulence genes gel+, ace+, and asa1+) showing necrosis of hepatic cells with pyknotic nuclei, disorganization of hepatic laminae, and dilation of sinusoids (arrow). (D) Liver tissue of albino rats, fed strain of E. faecalis strain EFS 18 (having two virulence genes, ie, gel−, esp+, and cylA+) showing well preserved renal corpuscles and less pronounced areas of inflammatory changes (arrow).

Mentions: Histopathological investigation showed areas of pronounced hemorrhage, necrosis, and distortion in the liver tissues (Figure 2A–D), which were more marked in rat tissues infected with EFC 12 than in rat tissues infected with EFS 18 and EFT 148. Other tissues examined did not reveal any significant difference compared with control tissue. The combination of cytolysin and Esp seems to confer more virulence on EFS 18 than EFT 148. An association between hemolysin production and virulence is well known for bacteria such as streptococci, pneumococci, listeria, clostridia, and some strains or serotypes of E. coli.41–43 Previous research suggests that hemolysin contributes to virulence in experimental and human enterococcal infections. In a rabbit model of endophthalmitis,44 infections caused by cytolytic E. faecalis resulted in 99% loss of retinal function at postoperative day 3, with near total destruction of retinal architecture, compared with loss of 74% in infections caused by non-cytolytic strains, which produced few changes.


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

Olawale AK, David OM, Oluyege AO, Osuntoyinbo RT, Laleye SA, Famurewa O - Infect Drug Resist (2015)

Pathogenic effects of Enterococcus faecalis strains on experimental animals (magnification 400×). (A) Liver tissue of albino rat (control group) showing normal tissue appearance. (B) Liver tissue of albino rat, fed with EFC 12 (having four virulence genes gel+, esp+, cylA+, and asa1+) showing pronounced renal corpuscles and areas of inflammatory changes (arrow). (C) Liver tissue of albino rat fed with EFT 148 (having three virulence genes gel+, ace+, and asa1+) showing necrosis of hepatic cells with pyknotic nuclei, disorganization of hepatic laminae, and dilation of sinusoids (arrow). (D) Liver tissue of albino rats, fed strain of E. faecalis strain EFS 18 (having two virulence genes, ie, gel−, esp+, and cylA+) showing well preserved renal corpuscles and less pronounced areas of inflammatory changes (arrow).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492643&req=5

f2-idr-8-181: Pathogenic effects of Enterococcus faecalis strains on experimental animals (magnification 400×). (A) Liver tissue of albino rat (control group) showing normal tissue appearance. (B) Liver tissue of albino rat, fed with EFC 12 (having four virulence genes gel+, esp+, cylA+, and asa1+) showing pronounced renal corpuscles and areas of inflammatory changes (arrow). (C) Liver tissue of albino rat fed with EFT 148 (having three virulence genes gel+, ace+, and asa1+) showing necrosis of hepatic cells with pyknotic nuclei, disorganization of hepatic laminae, and dilation of sinusoids (arrow). (D) Liver tissue of albino rats, fed strain of E. faecalis strain EFS 18 (having two virulence genes, ie, gel−, esp+, and cylA+) showing well preserved renal corpuscles and less pronounced areas of inflammatory changes (arrow).
Mentions: Histopathological investigation showed areas of pronounced hemorrhage, necrosis, and distortion in the liver tissues (Figure 2A–D), which were more marked in rat tissues infected with EFC 12 than in rat tissues infected with EFS 18 and EFT 148. Other tissues examined did not reveal any significant difference compared with control tissue. The combination of cytolysin and Esp seems to confer more virulence on EFS 18 than EFT 148. An association between hemolysin production and virulence is well known for bacteria such as streptococci, pneumococci, listeria, clostridia, and some strains or serotypes of E. coli.41–43 Previous research suggests that hemolysin contributes to virulence in experimental and human enterococcal infections. In a rabbit model of endophthalmitis,44 infections caused by cytolytic E. faecalis resulted in 99% loss of retinal function at postoperative day 3, with near total destruction of retinal architecture, compared with loss of 74% in infections caused by non-cytolytic strains, which produced few changes.

Bottom Line: The results showed differences in enterococcemia and hematological parameters between the control group and experimental animal group.White blood cell count, packed cell volume, and platelets were significantly reduced (P<0.05) in the experimental animals compared with the controls.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Sciences, Osun State Polytechnic, Iree, Nigeria ; Department of Microbiology, University of Ado-Ekiti, Ado-Ekiti, Nigeria.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus