In December 2024 NHS Care Homes suffered three deaths as a result of listeria poisoning. The deaths were investigated as part of a listeria outbreak linked to desserts supplied to NHS hospitals and care homes. The UK Health Security Agency (UKHSA) confirmed it is investigating the deaths as well as two non-fatal cases between May and December 2024
The Listeria bacteria was detected in a chocolate and vanilla mousse and a strawberry and vanilla mousse, both supplied by Cool Delight Desserts, UKHSA said – although it was not confirmed as the source of the infections. The threshold of listeria found in the desserts was known to be below the legal threshold of what healthy people can tolerate, the PA news agency reported.
The Food Standards Agency said that the desserts were being removed from the supply chain as a precaution while investigations continue.
Listeria is can have a harmful impact in care homes and places where people have weakened immune systems. The reason comes down to how this bacteria works and who it tends to hurt most.
Listeria monocytogenes is a type of bacteria that can cause serious illness, especially in people whose bodies aren’t great at fighting off infections—think the elderly, cancer patients, folks with chronic illnesses, or anyone taking medications that suppress their immune response. What makes Listeria tricky is that it doesn’t mind the cold. Unlike most bacteria, it can grow even inside a refrigerator. That means food that’s supposed to be “safe” because it’s chilled can still become contaminated.
In care homes, food safety isn’t just about following the rules, it’s about pre-emptive action to protect vulnerable people who are far more likely to become ill, or even die, from what might be a minor bug for someone else. Listeria infection can lead to severe outcomes like sepsis, meningitis, or miscarriage in pregnant women. Outbreaks in these settings can happen quietly, with no obvious signs until someone gets critically ill.
This is where the importance of a fridge temperature monitoring food safety system comes in.
Systems like Gurdstar Food Safety don’t just tell you what the temperature is right now—they record temperature data over time, send alerts if things get too warm, and provide proof that you’re staying within safe limits (usually 0°C to 5°C for chilled food). This matters because if a fridge creeps above the safe zone, even for a few hours, Listeria can multiply to dangerous levels. Manual checks are easy to forget or fake, but automated systems make mistakes less likely and create a solid audit trail.
If someone gets sick—or worse, dies—from Listeria, the fallout for a business or care home is massive. There’s the human cost, obviously, but the reputational damage can be just as devastating. News spreads fast. Regulators get involved. Families lose trust. You might be facing investigations, lawsuits, or even closure. Even if you fix the problem, rebuilding your reputation is an uphill battle. People remember the headlines, not the changes you made afterward.
In short: Listeria is a silent threat in settings with immune-compromised people. Proper fridge monitoring isn’t just a box to tick—it’s a vital part of keeping vulnerable people safe and protecting your business from the kind of incident that can ruin its reputation forever.
Listeria can grow on milk and a wide range of dairy products. Here’s how it works:
- Milk: Listeria can be present in raw (unpasteurized) milk, and if milk isn’t handled or stored properly, the bacteria can multiply—even in the fridge. Pasteurization kills Listeria, but if milk is contaminated after pasteurization (for example, through dirty equipment or containers), it can still be a risk.
- Other Dairy Products: Listeria can also grow on soft cheeses (like brie, camembert, blue-veined cheeses, feta, and queso fresco), as well as in products like ice cream, butter, and yogurt. Soft cheeses are especially risky because they contain more moisture and less acid, which creates a friendlier environment for Listeria to thrive. Hard cheeses and processed cheeses are generally safer, but they aren’t completely risk-free if they become contaminated after production.
- Why It’s a Problem: The real issue is that Listeria can keep growing at refrigerator temperatures, which is unusual for bacteria. That’s why even chilled dairy foods can become dangerous over time if Listeria is present.
Overview: Listeria can grow on most dairy products, especially if they’re made from unpasteurized milk or have been contaminated after pasteurization. Soft cheeses and unpasteurized dairy are the biggest risks, but even pasteurized products can be unsafe if not handled or stored properly.
The importance of Weekly cleaning and Temperature Monitoring is the gold standard in care homes or any setting with vulnerable people. Here’s why:
- Listeria can survive and even grow in cool, damp environments—like the inside of a fridge, especially if there are spills or food debris.
- Fridge temperatures need to be monitored so the EHO protocol of a 4-hour window can be followed. If fridges go over 5’c for a duration of 4 hours or more the contents should be discarded. This can be hard to monitor without a temperature monitoring system.
- A weekly clean removes spills, spoiled food, and any lurking bacteria before they get a chance to multiply.
- In busy environments, food gets moved around, things spill, and old items can get forgotten. A week is about as long as you want to go before things can get out of hand.
Monthly cleaning is better than nothing, but it’s not enough in high-risk settings. For homes with healthy adults, a monthly deep clean might be fine, but in care homes or clinics? Aim for weekly.
Temperature: Always Below 5°C
Absolutely, yes—keeping the fridge below 5°C (41°F) is crucial for preventing Listeria growth. This is the recommended safe temperature because:
- Listeria grows slowly, but steadily, at fridge temperatures—especially above 5°C.
- Most food safety guidelines (including the UK Food Standards Agency and CDC) recommend 5°C as the upper limit for chilled foods.
- The lower you go (without freezing things you don’t want frozen), the safer you are.
According to UK Environmental Health Officer (EHO) guidelines, if a fridge temperature rises above 5°C for more than four hours, any high-risk foods inside are considered potentially unsafe and should be discarded. This rule is particularly important in care homes, where residents are more vulnerable to foodborne illnesses like listeria, which can still multiply slowly at fridge temperatures and become dangerous as temperatures climb. Listeria is especially risky because it thrives in moist, chilled environments and targets those with weaker immune systems. That’s why a temperature monitoring system is so valuable—it provides a constant record and real-time alerts if the fridge temperature drifts out of the safe range, giving staff a chance to intervene before food safety is compromised. Having this level of oversight not only protects residents, but also helps care homes comply with EHO requirements and avoid the serious health and legal consequences of a listeria outbreak.
Key Points
- Weekly fridge sanitising is essential for care homes and anywhere with immune-compromised people.
- Fridge’s must maintain their temperature below 5°C at all times—this is non-negotiable for safety. A fridge monitoring system is essential to monitor this as fridges can reach high temperatures overnight, resulting in spoilt milk which no one is aware of.
Guardstar Food Safety is proud to supply Food Safety Systems and advise care homes around the UK.