IAHJ Spring 2021

Page 37


Salmonella Sampling: Achieving the Right Result Begins Outside the Chicken House Salmonella seems to be inextricably linked with poultry farming. Not so much due to a general belief that all salmonella comes from chickens, but because of the many measures put in place in the sector to prevent salmonella and reduce the risk to humans. One important measure within the EU is the determination of the salmonella status of each flock by collecting samples from the chicken house. But what is the correct way to take a sample and how can you reduce the chances of a false positive result? If the salmonella status of a flock is determined, products (such as eggs) from flocks infected with salmonella can be processed separately and undergo additional processing where necessary. This prevents vertical transmission and ensures that the food delivered to consumers is safe. As (part of) the costs for this processing are borne by the poultry farmer, a positive salmonella sampling will have a significant impact on business operations and the financial results. For layers, in the case of a positive result, it is sometimes possible to request a confirmation sampling by the government. For broilers and breeders, this option is not available. It is therefore important to minimise the chance of cross-contamination or sample mix-ups during sample collection and at the laboratory. Usually, you cannot see if an animal is infected with salmonella, so it is entirely possible that one of the houses or the farm is infected.

Hygienic Sample Collection is Particularly Important when Verification is Not an Option: Prevent an Incorrect Result

Figure 1. What you will need to take a salmonella sample.

How to Get Started A hygienic sample collection always starts with clean and aseptic or sterile sampling equipment, so this should not be stored on a dusty shelf but in a clean cupboard. You should also wash your hands before you start the sample collection. Label the sample pot or sample bag with the farm number, house number and the sample collection date, so that the sample can always be traced back to the house it was taken from. Then go to the house and put on a pair of clean, house-specific boots or overshoes as you step over the threshold (i.e. as you step into the house). Disinfect your hands or put on gloves. Then put on the boot swabs and walk around the house. While still in the house, place the boot swabs in the sample pot or sample bag and then seal it. Put the pot(s) or bag(s) down outside the house. Disinfect your hands again, then repeat the process in the next house. Make sure that the sampling equipment used in the next house is not contaminated by material from the previous house. I’ve Finished Taking the Samples; What’s Next? Once you’ve finished taking the samples, gather them together and clean the outside of each pot or bag if necessary. If there is faecal matter or dust on the sample pot or sample bag, this can cause cross-contamination or even infection of the laboratory worker during handling of the samples. You will want to avoid this, for yourself and for others. Then package the samples in a second, leakproof bag to keep them together, possibly grouping them by house and by farm, and send them to the laboratory along with a completed submission form (not in the bag with the samples). Avoiding Cross-contamination at the Laboratory The way work is carried out at the laboratory is also determined www.animalhealthmedia.com

Figure 2. What you should not do. Ensure hygienic sample collection. International Animal Health Journal 35

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