Shiga Toxin-Producing E. coli (STEC) and HUS Risk

Shiga toxin-producing E. coli (STEC), including serotype O157, is a dangerous group of gut bacteria that can cause bloody diarrhoea and, in a minority of cases, haemolytic uraemic syndrome (HUS) — a serious illness that can lead to kidney failure. It spreads through undercooked mince, contaminated fresh produce and unpasteurised products. Control it by cooking mince right through to 75°C in the centre, washing produce and preventing raw-to-ready cross-contamination. Key takeaways: STEC — including E. coli O157 — produces Shiga toxin that can cause bloody diarrhoea and, in a minority of cases, haemolytic uraemic syndrome (HUS), which can lead to acute kidney failure.. The infectious dose is very low, so even small lapses in cooking or hygiene can cause illness; young children, older adults, pregnant people and anyone with a weakened immune system are most at risk.. Mince, burgers, meatballs and sausages must be cooked right through to 75°C in the centre, because grinding spreads any surface bacteria all the way through the meat.. Wash fresh produce in safe water, keep raw meat separate from ready-to-eat food, and treat unpasteurised milk and juice as high-risk foods.. What is STEC and why is O157 so serious? Escherichia coli (E. coli) is a large group of bacteria that lives naturally in the gut of people and animals. Most strains are harmless and are simply used as an indicator of faecal contamination in food and water. The strains that cause serious foodborne illness are the Shiga toxin-producing E. coli — known as STEC, and sometimes called VTEC. The best-known member is serotype O157, but other serotypes can be just as dangerous. What sets these strains apart is that they produce a powerful toxin that damages the lining of the gut and, in severe cases, the small blood vessels of the kidneys. STEC matters out of proportion to how often it occurs. The infectious dose is very low compared with many other foodborne bacteria, so it takes only a small amount of contaminated food to make someone ill. Illness usually starts with stomach cramps and diarrhoea that can become bloody. In a minority of cases the infection progresses to haemolytic uraemic syndrome (HUS), a serious complication that can cause acute kidney failure and is most dangerous for young children, older adults, pregnant people and anyone with a weakened immune system. Typical symptoms: severe stomach cramps, watery then often bloody diarrhoea, and sometimes vomiting.. HUS warning signs can appear after the diarrhoea eases and may include reduced urination, tiredness and pallor — these need urgent medical attention.. Antibiotics are not routinely recommended for STEC and may increase the risk of complications, so prevention through food handling is critical.. How STEC gets into food Cattle and other ruminants carry STEC in their gut without becoming sick, so the bacteria can end up on the outside of carcasses during slaughter and dressing. When meat is minced, any bacteria on the surface are mixed all the way through the product. That is why mince, burger patties, meatballs and sausages carry more risk than a whole cut such as a steak. Meat processors manage this hazard tightly, but the final cook in your kitchen is the step that actually protects the customer. Fresh produce becomes contaminated in a different way — usually through faecal material reaching the crop via contaminated irrigation water, run-off, manure or handling. Leafy greens and sprouts are a recognised concern because they are often eaten raw, with no cook step to destroy bacteria. Unpasteurised milk and products made from it can carry STEC directly from the animal. Once STEC is in a kitchen, it also spreads by cross-contamination — from raw meat, dirty hands, boards, knives and cloths onto ready-to-eat food. Cooking mince, burgers and sausages to 75°C The single most important control for STEC in cooked foods is a thorough cook. Because grinding spreads surface bacteria throughout minced products, they must be cooked right through — you cannot serve a burger rare the way you might a steak. Aim for a core temperature of 75°C, checked with a clean, calibrated probe thermometer in the thickest part. Colour is not a reliable guide on its own; a patty can look brown before it is fully cooked, or stay pink when it is safe. Whole, intact cuts of muscle meat are lower risk because any bacteria stay on the surface, which is seared during cooking — this is why a steak can be served less than well done while a burger cannot. Reheat previously cooked foods to 75°C as well, and keep hot food at 60°C or above and cold food at or below 5°C to stay out of the 5–60°C danger zone where bacteria multiply. When food sits in that range, apply the 2-hour/4-hour rule to decide whether to use, refrigerate or discard it. Cook mince, burgers, meatballs, rissoles and sausages to 75°C in the centre.. Whole cuts (steak, whole roasts) may be cooked to preference, as bacteria remain on the outer surface that is seared.. Use a probe thermometer rather than relying on the colour of the meat or juices alone.. Controlling STEC on fresh produce and leafy greens Because produce eaten raw has no cook step, prevention starts with sourcing. Buy fruit and vegetables from reputable suppliers who can demonstrate safe growing and washing practices, and store them cold and away from raw meat. Wash leafy greens, salad items and other raw produce thoroughly in clean, potable (drinking-quality) water before use, and discard damaged or slimy leaves. Washing reduces contamination but does not reliably remove all bacteria, so it is a control, not a guarantee. Prepare produce on clean, dedicated boards and equipment — never the ones just used for raw meat — and sanitise afterwards. Sprouts (such as alfalfa and bean sprouts) are a recognised higher-risk item because the warm, moist conditions used to grow them also suit bacteria; take extra care with them, especially when serving vulnerable customers. The risk in unpasteurised milk, cheese and juice Pasteurisation is a heat process designed to destroy harmful bacteria, including STEC, in milk and juice. Raw (unpasteurised) drinking milk therefore carries a real risk of STEC and other pathogens, and its sale for human consumption is tightly restricted under Australian food regulation. Some cheeses made from unpasteurised milk are permitted only where they are made under specific, controlled conditions set in the Food Standards Code. For a food business, the safe default is to use pasteurised milk, cream and juice, and to know the status of any specialty dairy products you buy. Be especially cautious about serving unpasteurised products to young children, older adults, pregnant people and immunocompromised customers, for whom STEC and HUS are most dangerous. If you are unsure whether a product may be sold or served, check the requirements with your state or territory food regulator before putting it on the menu. Stopping cross-contamination and protecting vulnerable customers Even perfectly cooked mince becomes a hazard if it touches, or is handled alongside, ready-to-eat food. Keep raw meat below and away from ready-to-eat items in the fridge, use separate or clearly identified boards and utensils, and clean then sanitise surfaces and equipment between raw and ready-to-eat tasks. Thorough handwashing with soap and warm water — especially after handling raw meat or produce and after using the toilet — is a frontline defence, because STEC spreads readily from hands. Manage unwell staff carefully. Food handlers who have had diarrhoea or vomiting should not handle ready-to-eat food, and confirmed STEC can attract longer exclusion periods and medical clearance set at state and territory level. Settings that serve vulnerable people — aged care, childcare, hospitals — should be especially conservative, avoiding higher-risk raw and unpasteurised foods and applying temperature and hygiene controls rigorously. These controls sit within your food safety obligations under Standards 3.2.2 and 3.2.2A. Checklist: Mince, burgers and sausages cooked to 75°C in the centre, verified with a probe. Raw meat stored below and separate from ready-to-eat food at or below 5°C. Separate or clearly identified boards and utensils for raw and ready-to-eat. Fresh produce washed in clean drinking-quality water before service. Only pasteurised milk and juice used, or the status of specialty products confirmed. Surfaces and equipment cleaned and sanitised between raw and ready-to-eat tasks. Handwashing enforced after handling raw meat and produce. Staff with diarrhoea or vomiting excluded from handling ready-to-eat food. Common mistakes: Serving burgers or other minced products rare or pink in the middle, as you might a steak. Judging doneness by colour instead of measuring the 75°C core temperature. Using the same board or tongs for raw mince and then for salad or cooked food. Assuming a rinse removes all bacteria from leafy greens or sprouts. Serving unpasteurised milk or juice to young children, older adults or immunocompromised customers. Letting a food handler who recently had diarrhoea return to ready-to-eat tasks too soon.