In the past few years, we have seen an increase in customers asking for an onsite audit of their internal labs. These requests may occur when new tests are brought online or in-house, when there are questionable results or as a routine activity in the company’s food safety program. Not surprisingly, members of our technical team love doing these audits! We get to share our lab experience, technical microbiology knowledge and best practices to help our customers improve the quality of testing they perform. We always learn after an audit, seeing different operations and processes from the customer perspective.
Here are some observations from our most recent audits and a brief discussion on why the finding is important.
- Media for pathogen testing was not prepared correctly and there was no QC testing performed. Media is one of the most important parts of a microbiology test. Bad media may not grow the target organism if present, causing a false negative result. This means unsafe food could be released.
- pH of samples was not checked and adjusted before plating on Petrifilm. Each type of Petrifilm has a target pH range for samples to ensure the media works correctly and organisms can grow. If the pH is too low or high, plate counts may be underestimated.
- Pathogen samples were held in the fridge over the weekend between enrichment steps, a deviation from the validated method. Validated methods need to be followed as written unless a study is performed to assess the change. In this case, it is unknown what the impact of refrigerating the samples had on test results. It is possible that refrigeration affects pathogen growth.
There is immense value in conducting a lab audit, whether done internally or by a third party. A significant investment goes into the lab and results are often used to assess product safety or quality, so it is critical to ensure tests are done correctly. A lab audit is just one of the many ways we can partner with you to achieve your food safety and quality objectives. Let us know if you want to talk more and take us up on this opportunity to help you improve your processes!