An audit of laboratories in the United Kingdom has revealed a number of potential issues ranging from staff retention to a lack of shelf-life and virus testing knowledge.

The UK Health Security Agency (UKHSA) provides the UK’s National Reference Laboratory (NRL) for food microbiology for the Food Standards Agency (FSA).

The audit found that although the number of laboratories has remained stable since 2016, the number of food examiners has decreased from 55 to 39 between 2013 and 2023. One lab has six public analysts but 11 have none. Findings, recently reported, come from a survey sent to 14 Official Laboratories (OLs) in 2023 from the NRL to evaluate the capability and capacity for microbial testing of food.

Official microbiological testing in the UK requires food examiners to oversee the process, due to legislative requirements. UKHSA said the audit suggests that retention of these highly trained staff seems to be difficult.

There is good testing capability for Listeria and Salmonella in line with food safety rules, with only a few criteria seeing less capability, possibly because of low testing demand in these food categories.

There are some tests wher only a few labs are accredited including Cronobacter in dried products for infants younger than 6 months of age, with only one of 14 labs holding accreditation and histamine in fish wher four labs are accredited. UKHSA said low uptake may be because the tests are highly specialized or rarely requested in the UK. This makes maintaining accreditation and competence difficult.

Areas that need attention
There are no OLs able to detect staphylococcal enterotoxins in cheeses, milk powder and whey powder but there is an agreement with a lab in the EU that performs this test. Detection of Shiga toxin producing E. coli (STEC) in sprouts has continued to see good implementation.

Detecting antimicrobial resistant (AMR) bacteria in food is only carried out in two UK labs while none said they perform testing for viruses. Detection of viruses in food, such as norovirus and hepatitis A, has until recently been limited to one or two labs in the UK and focused on shellfish and fruit and vegetables. While viruses are not in the remit of the NRL for Food Microbiology, UKHSA said the survey indicates a review of resources may be needed to enable OLs to investigate potential sources of viral foodborne incidents.

Microbiological testing is done for commercial clients such as food companies, local governments, port health authorities, and for surveillance and outbreak purposes. The average number of official control samples received annually varied from none to 6,400.

Some labs had difficulty in classifying, processing or interpreting results for products with melted cheese on top, fresh fruit smoothies, and those wher it was not clear whether they were ready-to-eat or not.

There is increased uptake in proficiency tests (PT) by the OLs, with participation ranging from two to 11 different PTs, including the FEPTU European Food Microbiology Legislation (EFL) Scheme. Participation assures competence and quality when generating laboratory results, which is important for official controls and formal samples, said UKHSA.

only half the OLs perform shelf-life and challenge testing, which has remained stable since 2016. This area requires different procedures to microbiology testing of food and is difficult for labs to include in routine activities.