Introduction to Non-O157 STECs James Marsden Distinguished Professor Food Safety and Security Kansas State University SteakExpert 2012 What we know about STECs Emerging STECs (Shiga Toxin Producing strains of E. coli) Six strains of STECs have been associated with ¾ of the food safety illnesses in the United States (O26, O45, 0103, O111, O121, and O145 -- termed the “Big Six). What we know about STECs Illnesses associated with STECs are identical to E. coli O157:H7 Symptoms include diarrhea, bloody diarrhea, HUS and death Increased reports of illnesses may be due to a higher prevalence of possibly improved surveillance FoodNet reported 575 STECs between 2000 – 2006 (209 in 2006) What we don’t know about STECs No one really knows how prevalent these STECs are in nature or in the food supply FSIS estimates that the incidence in dairy cattle may be between 0-19% and the incidence in beef cattle feces and hides may be 19.4 – 56.3%; Pre-evisceration beef carcasses – >50%; Retail Ground Beef – 2-3% What we don’t know about STECs The beef industry has been successful in reducing the incidence of E. coli O157:H7 We don’t know for certain whether the same interventions that are effective on E. coli O157:H7 will also inactivate STEC strains. We don’t know enough about thermal resistance, acid resistance, effect of Aw and HPP We don’t know to what extent STECs are associated with beef What we need to know about STECs The ideal approach to the challenges posed by STECs would first involve a national baseline study and risk assessment Secondly, research is needed to identify and validate effective interventions. Thee beef industry has been focused on interventions for E. coli O157:H7 since the 1993 Jack-in-the-Box outbreak It’s possible that the food safety systems already in place for control of E. coli O157:H7 are effectively controlling nSTECs as well. However, that needs to be proven. What we need to know about STECs We need to better understand the biology of STECs We need to determine the thermal resistance, acid resistance, effect of Aw and HPP We need to identify modes of contamination and whether they are similar to E. coli O157:H7 Pathogenicity Not all E. coli strains are pathogenic. To be pathogenic, a strain must have the necessary properties to cause disease in human. These properties are called “virulence factors.” Exactly what virulence factors are required is unknown. Pathogenicity • E. coli can cause human disease when they possess stx1 or stx2. • Individuals infected with strains producing stx2 are more likely to develop severe disease than those infected with strains carrying Shiga toxin 1. • It is commonly thought that E. coli must contain stx1 or stx2 and eae (intimin) and its substitutes to have the highest chance of causing disease in humans – of course there are always exceptions. CDC Reports on STECs According to the US Centers for Disease Control and Prevention, nonO157 E. coli STECs (like O26, O45, 0103, O111, O121, and O145) cause 36,700 illnesses, 1,100 hospitalizations and 30 deaths in America each year Top Non-O157 Serotypes (CDC) O26 22% of non-O157 STEC O111 16% of non-O157 STEC O103 12% of non-O157 STEC O121 9% of non-O157 STEC O45 7% of non-O157 STEC O145 5% of non-O157 STEC Annual Submission of Non-O157 to PulseNet CDC E. coli O157 vs. Non-O157 E. coli Persons with non-O157 STEC USUALLY have less severe illness Non-O157 STEC include many serogroups, with varying virulence some typically cause only mild diarrhea others can cause HUS and death Non-O157 isolates predominantly have shiga toxin 1 Food commodities implicated outbreaks of non-O157 STEC infections with known food commodity, 1990-2007 Commodity Fruit-nuts Number outbreaks 3 Dairy 2 Leafy vegetables 1 No outbreaks due to beef Food items Juice, apple cider, berries Cheese, margarine Lettuce But it all changed in 2010 with the recall of ground beef because of human illness associated with O26 contamination Testing for STEC E. coli O157 Unusual feature: does not ferment sorbitol Non-O157 STEC Lack unusual features A group of organisms USDA Approach Top 6 serotypes Responsible for about 70% of non-O157 human illness. O26 O111 O103 O121 O45 O145 22% of non-O157 STEC 16% of non-O157 STEC 12% of non-O157 STEC 9% of non-O157 STEC 7% of non-O157 STEC 5% of non-O157 STEC How Do Pathogens Find Their Way into Beef Supply? Hide is the principal sources of these pathogens. Inadequate dressing practices is responsible for transferring generic and pathogenic bacteria from hides onto the carcass. Once on the carcass it is impossible to be 100% sure that you have eliminated them. The Ability to Detect Pathogens Hides Carcass (right after hide is removed) Carcass (after all interventions) Trim Ground Beef Message: If it is on the carcasses after hide is removed, sooner or later it will be on the subprimals, trim and ground beef. Control Hide is the principal source of most pathogens. An effective control in order of significance is: 1st - Dressing practices 2nd - Effective interventions – scientific support Works in your hands – validation Must make contact the potential pathogens Effective 3rd - Effective test and hold Control of STECs STEC are a natural part of the animal microflora. Some Non-O157 STEC can cause severe disease in humans. Non-O157 STEC is found at high frequency in preharvest samples (feces and hides). Non-O157 STEC is probably just as prevalent, maybe more, than O157 STEC in pre-harvest samples. Interventions used at the processing plants affect STECs similarly. HACCP Reassessment Issues Lack of information in incidence of Big 6 STECs in beef Lack of scientific documentation regarding validation of interventions and their effect on Big 6 STECs Questions about availability and relevancy of supplier COAs Questions about trim testing and finished product testing Test and Hold policy? HACCP Reassessment Issues According to the Federal Register Notice, USDA FSIS is assuming that the slaughter and processing interventions, testing programs and COAs in effect to address E. coli O157:H7 will apply directly to the Big 6 STECs There are potential problems with COAs as they relate to non-E. coli O157:H7 STECs Problems in Conducting Reassessment Without extensive testing for the Big 6 STECS – will the packers be willing to issue COAs and if they, will they be meaningful? Problems in Conducting Reassessment Another problem will be how to provide scientific support for slaughter and processing interventions Many NAMP members use ambient temperature control as a CCP for E. coli O157:H7 – There is a need for scientific documentation specifically to address the Big 6 STECs Problems in Conducting Reassessment US Beef Processors use processing interventions, including Sanova, organic acids and UV – USDA FSIS in the Federal Register assumes that interventions for controlling E. coli O157:H7 will be effective for the Big 6 STECs – In order for HACCP plans to be valid, there should be real scientific support for that assumption Interim Reassessment Steps 1. Request updated COAs from suppliers to address the Big 6 STECs 2. Assume all slaughter and processing interventions in place to address E. coli O157:H7 are effective at controlling other STECs 3. Conduct some level of testing for STECs in raw materials and finished product to verify the effectiveness of HACCP plans 4. Continue to reassess and provide scientific documentation as it becomes available USDA Testing of Trimmings for STECs USDA Testing for non-E. coli O157:H7 STECs began earlier this month Expect about 4-10% of the sample to be “potential positive” that is the enrichment is eae + stx Expect to have about 10 times the prevalence of that of E. coli O157:H7 Effect on trim prices (tested negative and positive) Industry Initiative on nSTECs Regardless of potential FSIS actions on nSTECs, it is in the interest of the beef industry to address the issue of nSTECs before it explodes into a major public health crisis. Scientific Issues Testing methods for the BIG 6 STECs are available and will improve over time USDA has funded research to answer many of the outstanding questions about the validity of slaughter and processing interventions These studies will eventually provide the necessary scientific documentation to support HACCP plans Long Term Solution Interventions designed to virtually eliminate surface contamination on beef carcass - Carcass Pasteurization Post-Chill UV/Photohydroionization Staged Antimicrobial Treatments Thermal – Steam or Hot Water The best outcome (sliver lining) Renewed focus on dressing practices and process control. Current E. coli O145 Outbreak 14 Confirmed cases in Southeastern US 1 Death Appear to be a sporadic outbreak So far, the CDC has been unable to identify the source of the outbreak This outbreak underscores the need to address Non-E. coli O157:H7 STECs Questions?