Abstract
Shiga toxin-producing E. coli (STEC) are important foodborne pathogens that causing serious public health consequences worldwide. The present study aimed to estimate the prevalence ratio and to identify the zoonotic potential of E. coli O157 isolates in slaughtered adult sheep, goats, cows and buffaloes. A total of 400 Recto-anal samples were collected from two targeted sites Rawalpindi and Islamabad. Among them, 200 samples were collected from the slaughterhouse of Rawalpindi included sheep (n = 75) and goats (n = 125). While, 200 samples were collected from the slaughterhouse of Islamabad included cows (n = 120) and buffalos (n = 80). All samples were initially processed in buffered peptone water and then amplified by conventional PCR. Samples positive for E. coli O157 were then streaked onto SMAC media plates. From each positive sample, six different Sorbitol fermented pink-colored colonies were isolated and analyzed again via conventional PCR to confirm the presence of rfbE O157 gene. Isolates positive for rfbE O157 gene were then further analyzed by multiplex PCR for the presence of STEC other virulent genes (sxt1, stx2, eae and ehlyA) simultaneously. Of 400 RAJ samples only 2 (0.5%) showed positive results for E. coli O157 gene, included sheep 1/75 (1.33%) and buffalo 1/80 (1.25%). However, goats (n = 125) and cows (n = 120) found negative for E. coli O157. Only 2 isolates from each positive sample of sheep (1/6) and buffalo (1/6) harbored rfbE O157 genes, while five isolates could not. The rfbE O157 isolate (01) of sheep sample did not carry any of STEC genes, while the rfbE O157 isolate (01) of buffalo sample carried sxt1, stx2, eae and ehlyA genes simultaneously. It was concluded that healthy adult sheep and buffalo are possibly essential carriers of STEC O157. However, rfbE O157 isolate of buffalo RAJ sample carried 4 STEC virulent genes, hence considered an important source of STEC infection to humans and environment which should need to devise proper control systems.
Highlights
Shiga toxin-producing E. coli are considered important foodborne pathogens of zoonotic importance which causing mild to severe bloody diarrhea with the emergence of the hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) which is a life-threatening disease (Karmali et al, 2010; Chileshe and Ateba, 2013).There are nearly more than 200 serotypes of STEC are recognized and the most frequent outbreaks of STEC are documented to be related to serotype O157: H7 strain throughout the globe (Abrar et al, 2020)
Only two (n = 2; 0.5%) out of 400 Recto-anal mucosal swabs (RAMS) samples showed positive results for E. coli O157 gene by conventional PCR, included one (n = 1; 1.33%) RAMS sample was detected in 75/200 RAMS obtained from healthy slaughtered sheep, while the remaining 125/200 RAMS samples obtained from goats showed negative results in the region of Rawalpindi
Another positive RAMS sample (n = 1; 1.25%) was detected in 80/200 RAMS collected from healthy slaughtered buffalos, while the remaining 120/200RAMS samples collected from cows showed negative result for E. coli O157 in the region Islamabad as shown as in (Table 3)
Summary
Shiga toxin-producing E. coli are considered important foodborne pathogens of zoonotic importance which causing mild to severe bloody diarrhea with the emergence of the hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) which is a life-threatening disease (Karmali et al, 2010; Chileshe and Ateba, 2013).There are nearly more than 200 serotypes of STEC are recognized and the most frequent outbreaks of STEC are documented to be related to serotype O157: H7 strain throughout the globe (Abrar et al, 2020). Shiga toxin-producing E. coli are considered important foodborne pathogens of zoonotic importance which causing mild to severe bloody diarrhea with the emergence of the hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) which is a life-threatening disease (Karmali et al, 2010; Chileshe and Ateba, 2013). E. coli O157: H7 serotype is the most important strains in hundreds of the other E. coli serogroups which live inside healthy humans and animals digestive organs it delivers an intense toxin that can cause dangerous disease (Gyles, 2007). In 1982 the pathogen STEC O157: H7 was recognized for the first time during an outbreak in the United States (US) (Acha and Szyfres, 2003; Fernandez, 2008). For public health importance nowadays E. coli O157: H7 is widely recognized as a foodborne pathogen (Xia et al, 2010)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
