We have discussed why environmental pathogen management is important and shared some cautionary tales. Now we can start the design of our programme and the first question to ask is: what are we looking for?

Traditionally, foods have been classified as high or low risk, based on the potential for pathogen contamination and subsequent growth in the product. Typically, fresh products like meat, soft cheeses and shellfish have been classed high risk, whereas low pH products like yoghurt and high heat products like UHT are considered low risk.

Whilst some of the rationale for high and low risk food makes sense, the boundary between this “black and white” distinction has become blurred. For example, following well documented pathogen outbreaks, our views for foods like fresh and frozen vegetables, ice cream, cereals and peanut butter have well and truly shifted. As we improve our diagnostic capability with tools like Whole Genome Sequencing, this list may well continue to grow.

In addition, the end-use of our food products by the consumer can push a low-risk food into a high-risk category. In the US, kale was not considered a “ready-to-eat” product until it became a raw superfood.

I think it could be more useful to look at food on a grey scale and I now routinely talk about “higher” risk and “lower” risk foods.

The reason I raise this point, is that several food factories I have visited do not monitor for environmental pathogens at all, based on the assumption that they produce a “low risk” food. My routine answer to this argument is that “we don’t know what we don’t know” (remember?) and at least should be aware of what’s lurking in our factory environment.

However, I do agree that an extensive, expensive pathogen management plan for a UHT or yoghurt plant does not appear to make sense, so let me introduce the concept of “target” and “surveillance” pathogens.

Target Pathogens

Listeria monocytogenes in chilled and ready-to-eat products, Salmonella in dry products, Cronobacter sakazakii in infant formula and E. coli in lettuce are all examples of pathogens that are linked to a specific food group. We know, either through scientific research or from experience that some foods are linked to particular pathogens.

When it comes to the food you make, you are probably very familiar with the pathogens that are a risk to your product and I call these the target pathogens. In a nutshell, “target” pathogens are the pathogens that are known to be a risk to your product and can make your customers sick.

Obviously, if you have a target pathogen associated with the food you make, your environmental pathogen management programme should focus on this pathogen.

For target pathogens, the purpose of your environmental pathogen programme is to “seek and destroy”! Because left unchecked, this pathogen is an immediate risk to your food business.

Surveillance Pathogens

Some food products have never been associated with a known pathogen, nor implicated in food poisoning outbreaks. As a result, the manufacturers of these foods have not been concerned about pathogens in the factory environment (or their product).

Whilst I understand this reasoning, I’m no longer convinced any food is safe from pathogens. The fact we are now dealing with antibiotic resistant “super bugs”, shows the incredible adaptability of micro-organisms. My thinking is that a contaminated factory environment may well lead to a “house bug” that could adapt to your product.

A food plant should never become a harbourage site for pathogens and for this reason I recommend lower risk food plants to have a programme for “surveillance pathogens”: pathogens that do not pose an immediate risk to your product.

The purpose to monitor for surveillance pathogens is to keep an eye on your factory environment and the focus of the programme shifts from “seek and destroy” to “seek and be aware”.

Will we look as hard for surveillance pathogens as for target ones? No! Looking for surveillance pathogens is like keeping an eye on the weather – you may actually not be able to do something about it, but it’s useful information to be aware of.

In summary, regardless of your product, an environmental pathogen management programme will provide very useful information. In both cases the purpose of “seek” remains but our response will differ.

For higher risk foods, an extensive environmental management programme for target pathogens is strongly recommended, preferably combined with a less frequent routine for the surveillance one. For example, a soft cheese plant may have an extensive programme for Listeria (Target) and a low-level programme for Salmonella (Surveillance).

For lower risk foods, a low frequency environmental programme for Salmonella and Listeria will be useful to understand your general factory condition.

Because you never know when to expect the unexpected.

About the Author

With over 30 years experience in the global food industry, Jack has led the international food safety assurance team at Fonterra and is currently working as an independent consultant. Jack has managed consultancy projects in the USA, Europe and China and led the design of Fonterra’s Environmental Pathogen Monitoring Programme. If you would like to get in contact with Jack, you can do so by emailing him at jack.vds@xtra.co.nz.