E. coli O157:H7 Characteristics, Pathogenicity, Spread and Control

1. Jordan University of Science and TechnologyFaculty of Veterinary MedicineDepartment of Pathology and PUBLIC Health Prof Akram Al Abboodi

2. E. coli O157:H7Characteristics, Pathogenicity, Spread and Control

3. E. coli Gram-negative rod, facultative anaerobe Normal flora of the mouth and intestine Protects the intestinal tract from bacterial infection Assists in digestion Produces small amounts of vitamins B12 and K Colonizes newborns GI tract within hours after birth E. coli 0157:H7 on the other hand produces toxins that cause severe damage to the lining of the intestine, and produce illness in humans.

4. Serotypes Antibody – antigen rxn Many strains • O antigen • Somatic (on LPS) • 174 antigens • H antigen • Flagella • 57 antigens • K antigen • Capsule and or fimbria antigen • 80 antigens • There are more than 700 different serotypes of E. coli • Distinguished by different surface proteins and polysaccharides

5. E. coli that cause human gastrointestinal illness • Shiga toxin-producing (STEC), also called Enterohemorrhagic (EHEC) • E. coli O157 serogroup • Non-O157 serogroups • Enteropathogenic (EPEC) • Enterotoxigenic (ETEC) • Enteroinvasive (EIEC) • Other types, less well characterized

7. E coli O157 Pathogenic E. coli are classified according to virulence factors(aea,hly,stxs) Intimin,Hemolysin,,Shiga toxin mechanisms of diseases(adhering) clinical signs(HUS)Hemolytic-uremic syndrome presence of O and H antigens (174 O, 57H)

8. The Shiga toxin-producing E. coli(STEC) pathotype refers to those strains of E. coli that are capable to produce one class of cytotoxins called Shiga toxin. Shiga toxin-producing E. coli (Sub set) that cause hemorrhagic colitis and hemolytic uremic syndrome are commonly knows as enterohemorrhagic E. coli (EHEC).

9. The STEC are also named verotoxin producing E. coli (VTEC). The name Shiga toxin (Stx), derived from similarity to a cytotoxin produced by Shigella dysenteriae serotype 1. verotoxin (VT), means they are cytotoxic to Vero cells.

10. Shiga toxin-producing E. coli (STEC) serotypes commonly isolated from beef cattle or their products. Therefore beef cattle or it is products can cause severe gastrointestinal disease in humans, such as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS).

12. Excretion Re-colonization Environment Death • SOURCES of E coli • Primary habitat: • large intestine, recto-anal junction? • warm, constant • nutrient rich • vigorous growth • Secondary habitat: • water, soil, sediment • cool, fluctuating • nutrient limiting • survival

13. Excretion Re-colonization Environment Death Has HACCP led to a reduction in human incidence?

18. Indirect contact (environmental) transmission

21. An estimated 73,000 cases occur annually in the United States. That number is probably many times multiplied due to poor reporting in less industrialized countries.

24. Example of a case study In February 2004, the Okinawa Prefectural Chabu Health Center and the Okinawa Prefectural Institute of Health and Environment reported multiple cases of E. coli 0157:H7 in a single family possibly after eating contaminated meat bought at a U.S. military commissary in Okinawa. Positive ID of E. coli 0157:H7 was made on 02/17/2004, after OCHC gathered samples of the frozen meat and analyzed it by means of pulse field gel electrophoresis (PFGE), . The samples were sent to Pulse Net USA for comparison to U.S. isolates, and matched E. coli 0757:H7. To exclude the possibility of contamination after opening of the meat packages, the U.S. Naval Hospital, Okinawa, Jp. Obtained unopened packages, leftovers, and the samples of human isolates, and compared all the samples.

25. Example of a case study Outbreak of Shiga toxin-producing E. coli O157 associated with consumption of watercress, United Kingdom, August to September 2013N Launders ()1, L Byrne1, N Adams1, K Glen1, C Jenkins2, D Tubin-Delic3, M Locking4, C Williams5, D Morgan1, An increase in the number of cases of Shiga toxin-producing Escherichia coli O157 PT 2 stx2 infection was reported in the United Kingdom on 9 September 2013. Of the 19 cases, 13 were interviewed, of which 10 reported consuming watercress purchased from one retailer. The retailer recalled pre-packed bagged salads containing watercress on 12 September. The descriptive epidemiology was supported by a case–case study performed after control measures were implemented. The outbreak strain was intimin (eae)positive and haemolysin (hylA) positive

29. Serogroups of 23 non-O157 STEC outbreaks, U.S., 1990-2007 Green shows most common serogroups of sporadic cases

30. Persons with HUS rarely had non-O157 STEC strains that produced only Shiga toxin 1 Isolates with clinical information submitted to CDC, 1983-2002 Overall, 61% of human non-O157 STEC produced only Shiga toxin 1 Brooks, JID 2005

31. Food vehicles in non-O157 STEC outbreaks, U.S., 1990-2007 N = 11

34. Pyramid of Surveillance Reported to health department & CDC STEC isolated Clinical lab tests for STEC Specimen obtained Person seeks care Person becomes ill Exposed to STEC

39. Control Being educated about foods that hold a certain risk to consumers is very important in preventing outbreaks of E.coli as well as other food borne pathogens. • Get off to a CLEAN start: One of the best ways to prevent the spreading of and illness is hand washing. This needs to be done before and after food handling as well as when switching between different foods. • CHILL food and stop bacteria cold: The danger zone for bacterial growth is between 40-140 degrees F. Chilling foods does not kill the bacteria it only stops growth. Cooking kills. • SEPARATE don’t cross contaminate: Raw meat should be placed on the bottom shelf in the fridge so it cannot drip onto other foods. When shopping, storing or preparing food, raw meat should be placed away from ready to eat foods. • COOK safely: Cooking meat to the safe temperature, 160 degrees F, kills E.coli. Hamburger can turn brown before it is at this safe temperature. The look, color, or feel of the meat is not a test for doneness, only trust the thermometer.

41. Meat Science 93 (2013) 463–468 Prevalence and antimicrobial susceptibility of Escherichia coli O157:H7 on beef cattle slaughtered in Amman abattoirAkram R. Alaboudi ,Tareq M. Osaili, Majdi Rahahlahb Department of Pathology and Animal Health, Faculty of Veterinary Medicine, Jordan University of Science and Technology, Irbid, 22110, Jordan

42. Sources of Carcass Contamination 1- Hide • Cattle hides is an important source of microbial contamination of carcasses (McEvoy et al., 2000). • E.coli O157:H7 and non-O157:H7 STEC can get it is way from cattle hides to the carcass (Barkocy-Gallagher et al., 2003, Nostosijevic et al 2008).

43. 2-Feces Many surveyed studies suggested that more than 20% of cattle shed VTEC in their feces and it might that these animals are the principle source of contamination (Elder et al. 2000; Smith et al. 2001). The carcasses could be contaminated with VTEC when the gut contents or fecal materials get in contact with meat surfaces.

44. Clinical lab testing for STEC • E. coli O157 • Unusual feature: does not ferment sorbitol • streak stool specimen onto plate containing Sorbitol-MacConkey (SMAC) medium • select clear colonies (others are pink) • O157 strains agglutinate when O157 antisera is added • Non-O157 STEC • Lack unusual features, look like good E. coli

47. Inoculation of buffered washed onto selective medium Chrom agar CT-SMAC medium Incubation at 37oC for 18h-24h Incubation at 37oC for 24 hrs five typical sorbitol- negative colonies five typical colonies Confirmation of pure colonies by indole formation , biochemical (MUG) and serological with antiserum (O157,H7) Identification by PCR; Stx1, Stx2, Hly, eae ,O157,H7

48. Results

49. Table 1: Number of samples with presumptive colonies of E.coli O157:H7 on CT-SMAC and CHROM agar. Growth on selective media

50. Confirmation of E.coli O157:H7