Systems check

29-Jul-2007 - Last updated on 16-Mar-2017 at 21:33 GMT

A worrying rise in listeriosis could see calls for hygiene standards in food factories to be raised even higher, as Rick Pendrous discovers

Microbiological experts advising the Food Standards Agency (FSA) recognise that hygiene in food factories has improved immeasurably over the past 20 years. But with concern mounting about rising levels of the disease listeriosis via foodborne contamination with the pathogen Listeria monocytogenes, there will be calls to raise the hygiene bar even further in the food supply chain over coming years - especially for ready-to-eat foods.

The Advisory Committee on the Microbiological Safety of Food (ACMSF) received a report in June, which highlighted a rising incidence of listeriosis across Europe. What most concerned members of the ACMSF, however, were that the reasons for the rise in this disease - among some of the most serious human foodborne illnesses - was unknown.

Vulnerable groups such as the elderly and people who are immunocompromised are most at risk. But the experts are flummoxed about the precise source of infection. According to the Health Protection Agency (HPA), in the first 22 weeks of 2007 there were 87 reported cases of listeriosis resulting in 25 deaths, of which 20 were in patients over 60 years of age.

"I am really puzzled from a food perspective," says Sainsbury's chief microbiologist Alec Kyriakides. "The incidence of listeria in food is at its lowest level ever ... it does worry me about the expectations in respect to food. To expect a step change in food [pathogen reduction] is probably unrealistic."

Carole Payne, food director for third-party hygiene inspection and certification body SAI Global/Efsis, adds: "I can't help thinking, the more you look for things, the more you find them. All the serious players are working to some very high standards now."

But Payne adds: "It is about maintaining systems, it's not about getting a certificate." One of the areas warranting more attention from an inspector's point of view is in-depth hygiene and cleaning, she says.

"We are not there all night, although we are there for at least a day-and-a-half, generally during operational hours because you want to see the process," she says. "But actually there is an argument which says it would be worth being there when they are not processing as well - and perhaps even on an unannounced basis, because then you could get a really true picture of the hygiene standards."

Guidelines suggest ready-to-eat food should contain no more than 100 colony-forming units per gramme (cfu/g) of Listeria monocytogenes at point of sale. However, a report in the publication Communicable Disease and Public Health from as long ago as September 2000 stated: "Counts of this level may also indicate a significant failure of hygiene standards in the preparation and/or storage of such foods."

Recent surveys carried out by the Local Authorities Coordinator of Regulatory Services (Lacors) and the HPA, showed that from 2,981 samples of vacuum-packed and modified atmosphere packed (MAP) cooked meats at the end of their shelf-life there was "a considerably high percentage of contamination", according to HPA infection researcher Jim McLaughlin. Of the total, 190 exhibited contamination with Listeria monocytogenes while 27 samples were at levels above 100cpu/g.

The worrying question now increasingly being asked by the experts is: 'Are products with Listeria monocytogenes levels below 100cpu/g safe?' Some fear that there could be a cumulative affect for some vulnerable groups, such as the elderly. For them, consumption of food with lower levels of contamination could increase the risk of infection if the contaminated food is consumed regularly. Foods that are particularly susceptible include soft ripened cheese, vacuum-packed pâté and sliced meats, which have a long shelf-life.

If the cumulative affect hypothesis is true, this could have serious implications for many older people who tend to eat the same types of food repeatedly on a day-to-day basis.

McLaughlin recognises that great strides have been made by the food supply chain in improving hygiene: "Compared to the 1980s, manufacturers are much, much better." However, he adds: "There are still problems out there in the food chain and it's about the strategy of dealing with those."

On the issue of safe Listeria monocytogenes levels, he says: "I feel uncomfortable about some of the lower levels - especially in food given to vulnerable groups, such as in hospital." His concerns are specifically related to sandwiches, where questions have also been raised about poor hygiene controls (such as storing sandwiches for extended periods above 8°C) before they are consumed by patients.

Irradiation and disinfection

Clearly the food industry has the primary responsibility for ensuring the food it supplies is safe. But, if it has to start shouldering more responsibility for what happens to the food after it leaves its control, this could re-ignite the debate about permitting the use of processing technologies which reduce food poisoning risks caused by 'temperature abuse' further along the supply chain - potentially, even as far as people's homes and fridges.

But can the industry practically be expected to ensure that food contains zero pathogens without the adoption of techniques such as irradiation - which zaps the bugs completely? At the moment, irradiation is only legally permitted on a very limited range of foodstuff in Europe, notably some herbs. In contrast, in the US irradiation is used to kill off potential bacteria, such as Escherichia coli (E.coli) in minced beef. It is used as an insurance policy, because of the US's lengthy supply chains, which would otherwise provide ample opportunity for pathogenic microbes to multiply to dangerous levels.

Although some European research has pointed to potential links with increased cancer risk when certain fatty foods are irradiated, the bigger concern seems to be that such a safety net would encourage bad practices and deter adherence to good hazard analysis critical control point (HACCP) procedures along the supply chain - something that would be most undesirable.

Following risk assessments carried out by the European Food Safety Authority, the ACMSF is considering the use of 'disinfection' techniques using four different antimicrobial surface treatment chemicals on carcases of chickens contaminated with campylobacter (see Food Manufacture, July p23). Similar techniques could also be approved for treating pork contaminated with salmonella.

Some ACMSF members raised concerns that the approval of these treatments could encourage bad control practices, although others suggested they could prove effective where on-farm controls have failed to work.

Ultimately, assuming risk assessments exonerate them, the use of any novel treatment process to kill off pathogens will come down to consumer acceptance, since products treated will have to be labelled. At the moment, more futuristic processes such as using viruses in the form of bacteriophages to disinfect poultry or irradiation to kill off E.coli in minced beef, are unlikely to receive public approval. But McDonald's senior food safety manager for Europe Bizhan Pourkomaillian, believes Europe will eventually follow the US lead in permitting the use of irradiation.

Allergens of growing concern

It's not just microbiological pathogens that are causing manufacturers increasing problems. While regular surveys help to ensure that potential problems arising from other contaminants such dioxins and polychlorinated biphenyls (PCBs), heavy metals, radionuclides and various other fungal contaminants such as mycotoxins are kept in check, one area of growing concern is the presence of undeclared allergens in food.

Poor allergen control and labelling is causing rising numbers of product recalls. Some even suggest the problem of allergens could equal those caused by the illegal dye Sudan 1.

What makes the allergen issue even more problematic is that no lower limits for contamination levels exist and, according to a spokesman for RSSL, which offers manufacturers specialist services to resolve potential allergen problems: "Nobody anywhere will say that this level of allergen contamination is safe or unsafe because it is so much dependent on individual response."

One thing is certain, pressure on suppliers to improve their hygiene standards and reduce levels of contamination of their products is set to increase. "As retailers are leading the charge for stricter standards of food safety and are unrelenting in pushing costs back to their suppliers, it is becoming increasingly important that manufacturers have not only the right protection in place but also have appropriate pre-emptive risk management systems in place," says Chris Woodcock, md of risk management PR consultancy Razor.

While the FSA's focus on reducing food safety incidents has cut foodborne illness in the UK by 19.2% between 2001 and 2006, you can expect the regulator to be looking for further improvement going forward. FM

Key Contacts