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Jordan University of Science and Technology Faculty of Veterinary Medicine Department of Pathology and PUBLIC Health Prof Akram Al Abboodi. E. coli O157:H7 Characteristics, Pathogenicity, Spread and Control. E. coli. Gram-negative rod, facultative anaerobe
Jordan University of Science and TechnologyFaculty of Veterinary MedicineDepartment of Pathology and PUBLIC Health Prof Akram Al Abboodi
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.
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)
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).
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.
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).
Has HACCP led to a reduction in human incidence?
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.
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.
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
Green shows most common serogroups of sporadic cases
Isolates with clinical information submitted to CDC, 1983-2002
Overall, 61% of human non-O157 STEC produced only Shiga toxin 1
Brooks, JID 2005
Reported to health department & CDC
Clinical lab tests for STEC
Person seeks care
Person becomes ill
Exposed to STEC
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.
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.
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.
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.
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.
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
(Barkocy-Gallagher et al., 2003, Nostosijevic et al 2008).
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.
Incubation at 37oC
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
Table 1: Number of samples with presumptive colonies of E.coli O157:H7 on CT-SMAC and CHROM agar.Growth on selective media
Figure 3: Multiplex PCR for detection of virulent and toxigenic gene for E.coli O157:H7. Electrophoresis analysis (2% agarose gel) of PCR patterns for E.coli O157:H7 detection. Lane M= DNA ladder marker (Promega, USA). Lane 1 = positive control E.coli O157:H7 (ATCC # 43895). Lane 4, 6, 8, and 10 = positive result for (hly , Stx1, aea, Stx2,) with expected band size 166, 210, 397, 484 respectively. Lane 2, 3 = negative control. Lane 5, 7, and 9 No sample.
(Borhom et al., 2002, Tutenel et al. 2003b).
(Laegreid et al., 1999; Bonardi et al., 2001; Chapman et al., 2001; Conedera et al., 2001; Meyer-Broseta et al., 2001; Paiba et al., 2002).
0.2% reported In the U.S (FSIS, 1994).
The prevalence of E.coli O157:H7 on beef sample under study were 10%, 8.3%, and 7.8% for hides, feces and carcasses respectively.
Contamination of carcasses with VTEC can occur when gut contents or fecal matter come into contact with meat surfaces.
(Chapman et al 1994; Elder et al 2000; Bonardi et al 2001., Barkocy-Gallagher et al 2003).
Therefore the main sources of possible carcass contamination source in abattoir are both of hides or fecal content. However possible cross contamination from utensils and employers has not to be neglected.
The distribution of E.coli O157:H7 among hides and carcasses depends mainly on level of hygienic precautions taken during slaughtering; hide removal evisceration and carcass dressing.
The apparently high 7.8% prevalence on carcasses surfaces reported in this study is most likely related to no good hygienicmeasures applied in studied abattoir .
Non- pathogenic E.coli O 157:H7 strains (without toxins factors) have also been identified from feces or beef carcass by other researchers
(Cerqueira et al., 1999; Guyon et al., 2001; Rogerie et al., 2001; Genevieve et al., 2005).6% NON TOXIGENIC ISOLATES
The minimum inhibitory concentration (MIC) values for 40 chosen E.coli O157:H7 isolates :
1- All isolates were susceptible to
(Gentamicin, Ampicillin, Tetracycline, Ciprofloxacin).
2- 50% of the isolates were resistant to three antibiotics (Erythromycin, Vancomycin and Neomycin).
3- 25% were multi resistant to four antibiotics
(Erythromycin, Vancomycin, Doxycycline ,Neomycin).
4- 5% resistant to five antibiotics
(Erythromycin, Vancomycin, Doxycycline, Neomycin , Streptomycin).Susceptibility to antimicrobial agents
The results of present study indicated that E. coli O157:H7 were susceptible to gentamicin and ciprofloxacin, which come in agreement with local Jordanian isolates from sheep and goat(Tarawneh et al., 2008) and other studies in USA among E. coli O157:H7 isolates from humans, cattle, swine and food, where all E. coli O157:H7 isolates, regardless of the source of isolation were susceptible to gentamicin and ciprofloxacin
(Schroeder et.al, 2001; Steve et.al, 2005).
all E.coli O157:H7 tested were also susceptible to tetracycline which again comes in parallel with Dontorou et al.,2003, testing three isolates obtained from ewes’ milk, fresh sausages and swine intestines in Greece.
The uses of IMS showed increased sensitivity of the isolation method.
The results of this study may help in establishing a risk based analysis systems for E.coli and developing criteria for routine microbiological food standardization.
1- Further studies could follow to determine the prevalence of E. coli O157:H7 in other animal’s species from different farms and slaughterhouses
3- Further studies are needed to determine other E.coli serotypes and shiga toxins subtypes.