The polymerase chain reaction (PCR) method can detect 2-40 colony forming units (cfu) per 25g of sample and is specific for STEC.
Foods at risk of contamination include raw meat, especially raw ground beef and seeds intended for sprouting.
Campden BRI has a category three laboratory which is required for STEC testing and needs an enhanced level of containment because STEC are highly pathogenic.
It developed, optimised and validated the method as part of its £2m annual research programme.
ISO standard revision
Meanwhile, ISO 16140:2003 for validation of alternative microbiological methods has been revised.
The multipart standard provides a specific protocol and guidelines for the validation of methods both proprietary (commercial) or not.
Proprietary methods are generally cheaper to use, produce results faster than traditional culture and are simpler to perform as they require fewer technical skills.
ISO 16140-1:2016, Microbiology of the food chain – Method validation – Part 1: Vocabulary, describes the terminology used in microbial testing, while ISO 16140-2:2016, Microbiology of the food chain – Method validation – Part 2: Protocol for the validation of alternative (proprietary) methods against a reference method, looks at the validation of proprietary microbiological methods.
ISO 16140-2 includes the method comparison study and the inter-laboratory study, with separate protocols for validation of qualitative and quantitative microbiological methods.
“The validation according to ISO 16140-2 will lead to a higher reliability of the alternative method test result and the users will benefit from having microbiological test results available sooner. Most likely, this will contribute to greater food safety,” said Paul in ‘t Veld.
Four other parts of ISO 16140 are still under development.