Column Gerard Kramer: CSI Salmonella

With great regularity, we detect Salmonella in feed raw materials, animal by-products, and raw chicken meat. Fortunately, we find Salmonella far less often in food products, because in that case the customer must immediately initiate a recall. The impact of such a recall is significant. In situations like this, the customer’s very first question is almost always: “Are you sure there wasn’t a mistake in the lab?” In the past, we often found ourselves at a loss for words: “Well, that’s unlikely, because we have taken numerous precautionary measures, but…”

Using classical serotyping based on the Kauffmann–White scheme, we were ultimately able to establish that it was not our control strain, nor the strain from another positive sample in the same series. However, that clarity took time: the result was only available after ten days. That waiting period was a problem. For customers in the animal feed sector as well. Entire batches remained blocked until it was clear whether a notifiable serotype had been found, or a variant that posed no risk to the target animal.

Fortunately, Check&Trace 2.0 is now available, a PCR method that allows us to identify the serotype within a matter of hours; a major step forward in reliability, speed, and source tracing. The method offers so many advantages that we now use this test as an additional confirmation for all positive samples. This allowed us to quickly demonstrate that the same unique serotype kept appearing at intervals in environmental samples from a customer. Without any doubt, it was the same source, which clearly had not yet been eliminated. Incidentally, we later detected the same serotype at the processor handling a residual stream from the customer’s factory. In a second case, we were able to immediately confirm that large series of contaminated samples from one specific customer had not contaminated other samples.

The additional costs are more than justified. For the customer, speed and traceability are essential. And for us, it provides extra peace of mind and solid assurance of the result.

Gerard Kramer
Agro-Food Specialist at Nutrilab