The United Kingdom’s top food microbiology lab has continued to see a drop in communications with European counterparts after Brexit.

Findings come from a report covering work of the UK’s national reference laboratory (NRL) for food microbiology between April 2022 and March 2023.

The UK Health Security Agency (UKHSA) provides the service for the Food Standards Agency (FSA) and Food Standards Scotland (FSS). It covers Listeria monocytogenes, coagulase-positive staphylococci, E. coli, Campylobacter, Salmonella, and antimicrobial resistance.

EU exit impact

The UK NRL had reduced opportunities with European Union Reference Laboratories (EURLs) due to EU exit, but participated in certain activities. It is no longer on the EURL Listeria challenge testing working groups and has been unable to attend all EURL annual workshops and training sessions. Certain presentations are on private webpages, which can no longer be accessed.

Despite some restrictions, the NRL attended the proficiency testing part of three of six EURL meetings remotely. The NRL gave advice to FSA, Official Laboratories (OLs) and other stakeholders and liaised with FSA on UK lab capabilities, including responding to queries.

Other work with the FSA included feedback on national monitoring plan sampling priorities and results of a Shiga toxin-producing E. coli (STEC) in flour study.

After the COVID-19 pandemic and leaving the EU, there has been a downward trend in EpiPulse and other alerts being sent to the UK NRL. In the latest reporting period, only one query was received from the Salmonella EURL regarding monophasic Salmonella Typhimurium and whether the strain had been seen in the UK in 2021-22, to which the NRL replied that it had not.

An audit report on Official Laboratories’ capabilities in England, Scotland, Wales and Northern Ireland is due to be published shortly. The NRL is also working on a review of AMR in Listeria monocytogenes and other Listeria in food.

Since exiting the EU, the UK has been developing a strategy for border controls on imported products from EU and non-EU countries, including animal and plant products and high risk food and feed of non-animal origin. The NRL met with the FSA to clarify sampling arrangements and expected sample numbers. However, delays in implementation of new sampling requirements for imported foods from the EU have meant that planning for additional testing within the OLs has also been delayed, according to the report.

Proposed activities for April 2023 to March 2024 include meetings with the Animal and Plant Health Agency (APHA) for AMR, Campylobacter and Salmonella, liaising with CEFAS on E. coli and Salmonella in shellfish and with Campden BRI to discuss challenge testing activities, and monitoring Official Laboratory performance.

Salmonella in UK eggs

In other news, the FSA has looked at Salmonella in UK-produced table eggs. The agency said the analysis does not indicate there is a need for another risk assessment. 

A risk assessment in 2016 found that due to a significant reduction in the risk from Salmonella in UK hen shell eggs produced under a recognized farm assurance scheme, such as the Lion Code or equivalent, the risk to consumers was very low. This led the FSA and FSS to update public advice on eating eggs in 2017, so that vulnerable groups could consume raw or runny eggs produced within an assurance scheme.

Eggs and egg products were the food type most commonly linked to Salmonella outbreaks in the UK between 2015 and 2020, said the review.

Between 2015 and 2019, 954 confirmed cases of salmonellosis were associated with consumption of eggs and/or egg products. This is a similar number of infections per year as reported in the 2016 assessment. Ten of 15 outbreaks had fewer than 45 cases. The largest incidents occurred in 2016 with 158 cases, in 2017 with 162 cases and in 2018 with 259 cases.

Two outbreaks of around 100 cases each were linked to Lion Code eggs. The 2016 risk assessment only found one small outbreak in 2009 traced to Lion code eggs. 

Prevalence of all Salmonella types in laying flocks in the UK in 2017 to 2021 was similar to 2009 to 2016 levels. However, the prevalence of regulated Salmonella serovars and Salmonella Enteritidis has roughly doubled in 2017 to 2021 but still remains within National Control Program (NCP) requirements.

Since the 2016 report, the implementation of whole genome sequencing for Salmonella surveillance by UK public health agencies has become routine. This has increased the sensitivity and specificity of case ascertainment in outbreak investigations, and confidence in source attribution, said FSA.

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