The search for the presence of Escherichia coli O157:H7 and Stx1/Stx2 gene in cattles and diarrheal human stools and some foods

Infectious diseases originating from foods constitute a serious threat for human and public health. The toxin–producing strains of E. coli, which one of these causative organisms, (Shiga–toxin-STEC or Verotoxin-VTEC) can cause serious infections, and even death. The basic reservoir of STEC is the cattle, and although it does not cause clinical disease in the cattle, it causes serious food–origin infections in humans. Humans can be infected through direct contact with the stools of carrier animals, contaminated water and soil, with consumption of half–done minced meat other animal–origin products or contaminated vegetables or fruits. Minimal infectious dose of E. coli O157 is low, and it has the capability of causing serious infections. In this study, it was aimed at detecting E. coli O157:H7, EHEC and toxin genes in stools of animals aged between 2 and 4 found in Afyonkarahisar Province and districts and in milk, products including fermented sausage and salad, and in the stools of patients with diarrhea. With this purpose, 718 speciments consisting of stools of 237 animals collected from different areas in Afyon (Şuhut, Sinanpaşa, Tatarlı / Haydarlıand Bolvadin) and 162 milk specimens from some of these animals, 106 fermented sausage specimens and 103 salad specimens as well as stool specimens of 110 patients who applied to outpatient clinics of Afyon Kocatepe University Hospital with diarrhea were cultured in modified Tryptic Soy Broth (mTSB) medium for bacterial enrichment. After eliminating the parasites and commonly seen bacteria in the human specimens with conventional diagnostic methods, they were first passed to MacConkey Agar (CT–SMAC) medium containing Cefixime–Tellurite Sorbitol; after this three colonies that grew in this medium from each that did not ferment sorbitol were selected and passed to Violet Red Bile Agar (VRBA) medium containing 4–methylumbelliferyl b–D–glucuronide (MUG) and were plaques left to incubate for 18 hours at 37oC. Colonies that grew during the incubation were subjected to UV (Herolab UVT – 20 M, Germany) test (366 nm) by with identification purposes by placing plaques on the light source of the UV device, and those colonies that did not produce fluorescentradiation were selected and subjected to biochemical separation tests including Indole, Methyl Red, Voges Proskauer, Kligler Agar, Citrateand Urea. As a result of the tests, existence of E. coli that does not ferment sorbitol was found in 63 specimens out of 237 animal stool specimens tested (26,58%), in 32 raw milk specimens out of 162 specimens tested (19,75%), in 13 fermented sausage specimens out of 106 specimens tested (12,26%), in 17 specimens out of 103 specimens tested (16,50%) and in 15 patient stool specimens out of 110 specimens tested (13,63%); and with the latex agglutination tests carried out on these isolates (Wellcolex, Remel UK) O157 antigen was detected 5,48% in animal stool (13/237), 2,46% in raw milk (4/162), and 0,94% in fermented sausage (1/106), H7 antigen was found in none. Furthermore, stx toxin gene has been detected EHEC (ABI 7500 Fast, England) (Liferiver, China) test using Real–time PCR in animal stool by 20,6% (49/237), in raw milk by 16,6% (27/162), in fermented sausage by 1,8% (2/106), in salads by 3,8% (4/103) and in patients' stool specimens by 1,81% (2/110). The serious morbidity and mortality of EHEC infections with complications including hemolytic uremic syndrome and hemorrhagic colitis, and its epidemiologic significance, show the requirement of investigating E. coli O157:H7 at least in patients presenting with bloody stool. Good hygiene and hand washing before eating and preparing food is required to prevent contamination from contact with animals and their surroundings. Ensuring the safe supply of food requires hygienic operation from the farms to table ware as well as interdisciplinary coordination through the creation of a multidisciplinary understanding between the operations and the state management.