From the detection of Listeria monocytogenes to the risks associated with edible insects and Clostridium perfringens, food safety can no longer be considered solely at the level of the finished product. During a session organised with the French Society for Microbiology at Forum LABO, several experts showed how new analytical methods can help us better understand contamination and the connections between the environment, animals, food and human health.

Listeriosis remains a major public health concern, particularly for vulnerable populations. For food manufacturers, however, detecting Listeria monocytogenes is not always enough: it is also important to determine which strain is present and where it comes from.

MLST typing can differentiate strains according to their genetic profile, but it requires sequencing and several days of analysis.

To speed up this process, ANSES developed GenoListeria, a real-time PCR method capable of identifying around 30 major clonal complexes. Validated through an interlaboratory study involving 15 laboratories from 11 European countries, the method provides much more discriminatory information than traditional serotyping approaches.

Genetic characterisation becomes particularly valuable when applied directly to the production environment.

By comparing strains found in raw materials, drains, processing areas and finished products, it becomes possible to reconstruct contamination pathways. A company can determine whether contamination originated from a supplier or raw material, or whether a particular strain has become established within the production environment.

This information can guide targeted corrective actions: reinforcing cleaning in a specific area, increasing controls on incoming materials, auditing a supplier or monitoring the recurrence of the same clone over time.

A new version of the method, GenoListeria Detect, is also under development to analyse samples directly from the enrichment stage. Initial tests have identified samples containing several clonal complexes where conventional methods detected only one.

Food microbiological safety must also adapt to the emergence of new foods. In Europe, insects intended for human consumption fall under the Novel Food regulatory framework.

Mealworms, crickets and other authorised species offer several potential advantages, including high protein content, efficient production and relatively low water requirements.

But “new” does not mean “risk-free”. Like any other food, insects require a comprehensive hazard analysis before being placed on the market.

Potential hazards can be physical — particularly when whole insects are consumed — as well as chemical or biological. Discussions during the session also highlighted the importance of considering certain contaminants, spore-forming bacteria and allergens, including potential cross-reactions in people allergic to crustaceans.

The development of this emerging food sector must therefore be accompanied by analytical and risk-assessment methods adapted to its specific characteristics.

Another example is Clostridium perfringens, a bacterium capable of producing several toxins and associated with food poisoning.

It can be found in the digestive systems of humans and animals, but also in soil, water and other environments. Its ability to form spores allows it to survive unfavourable conditions and resume growth when conditions improve.

The challenge is that not all strains present the same level of risk. Simply detecting or counting the bacterium in food does not necessarily provide enough information about its pathogenic potential.

Research is therefore increasingly focusing on virulence genes, toxins and the genetic diversity of strains. The aim is to distinguish simple bacterial presence from contamination that represents a genuine risk to consumers.

A research project involving the cattle, pig and poultry sectors studied C. perfringens directly in several slaughterhouses. More than 1,800 samples were collected from carcasses, processed meat, surfaces and air.

The analyses showed that the bacterium can be found at different stages of the production process. Genetic typing can then reveal the circulation of the same clone within a facility, or even its persistence over time.

This information can help manufacturers assess the effectiveness of their control measures. If the same strain reappears several months after cleaning or disinfection, it may indicate a persistent contamination source requiring additional corrective action.

These studies illustrate the importance of the One Health approach, which considers human, animal and environmental health as interconnected.

Understanding a foodborne outbreak therefore requires looking beyond the contaminated food itself. The entire chain may need to be considered: livestock, raw materials, the production environment, equipment, processing, finished products and potentially the wider natural environment.

Research on C. perfringens is now extending to soils to investigate possible genetic links between strains found in the environment, those circulating through food-production chains and those involved in human food poisoning.

Real-time PCR, genome sequencing, virulence markers and source attribution are gradually transforming food microbiology.

The question is no longer simply “Is this bacterium present?” It is increasingly about understanding which strain is present, whether it represents a genuine risk, how it circulates and where it comes from.

This evolution could enable more targeted preventive actions, better monitoring of production environments and, ultimately, stronger food safety throughout the entire chain.

Article based on the session dedicated to food microbiological safety through a One Health approach, organised with the French Society for Microbiology at Forum LABO.