Research and analysis

2024 to 2025 report of UK national reference laboratory for food microbiology

Updated 25 September 2025

Activities for Listeria monocytogenes, coagulase-positive staphylococci, Escherichia coli (including STEC), Campylobacter, Salmonella and antimicrobial resistance.

Executive summary

The UK National Reference Laboratory (NRL) for food microbiology is provided by UK Health Security Agency (UKHSA) for the Food Standards Agency (FSA) and Food Standards Scotland (FSS) to comply with assimilated Regulation (EU) 2017/625 for Official Control Regulations (OCRs) for food safety. This annual report details NRL’s activities for Listeria monocytogenes, coagulase-positive staphylococci, Escherichia coli (including Shiga toxin-producing E. coli (STEC)), Campylobacter, Salmonella and antimicrobial resistance (AMR) between April 2024 and March 2025.

The NRL liaises with and have maintained participation of the offered activities from the European Union Reference Laboratories (EURLs), post EU Exit. To keep abreast of emerging issues, developments and research related to the 6 responsibilities, the NRL regularly acquires or seeks information from relevant organisations. Information is disseminated to the Official Laboratory (OL) network, the FSA and other stakeholders through NRL quarterly newsletters and emails. The 2024 User Day was attended by 12 OLs and other stakeholders, either in-person or through a Teams link. The fourth OL audit report has been completed and findings are published online.

The UK NRL received requests for expert advice and support from FSA, OLs and other stakeholders. It includes providing information for an EU audit in November 2024 to evaluate the UK official control and certification systems over the production of milk and dairy products for human consumption destined for export to the EU. The NRL attended 2 EURL meetings remotely: the Proficiency Testing (PT) part of the STEC EURL meeting and the antimicrobial resistance (AR) EURL PT webinar. Training was offered by 2 EURLs and the UK NRL attended: a 5 day training on the ‘Detection of STEC in food matrices according to the ISO TS 13136:2012 and the characterization of the isolated STEC strains’ at the STEC EURL and a 4 day training on Oxford Nanopore sequencing delivered by the AR EURL. To keep informed of methodology developments, relevant webinars, seminars and training were attended by the NRL, including an ‘Advancing STEC diagnostics’ workshop with industry, public and government authorities. The NRL has reviewed draft Standards from the British Standards Institute (BSI) AW/9 food microbiology committee and is a member of the European Committee for Standardization (CEN) WG2 expert working group for the revision of the ISO TS 13136 (polymerase chain reaction (PCR) detection of Shiga toxin-producing Escherichia coli).

There are 16 relevant methods listed on GOV.UK which the NRL provided upon request to 9 laboratories. The NRL reviewed 2 general methods and performed 2 impact assessments on relevant external documents which generated no significant changes to referred methods.

The OLs are mandated to participate in the European Food Microbiology Legislation (EFL) PT scheme and the NRL evaluates their performance. All 14 OLs registered to participate in at least one of the 4 distributions available from the 2024 to 2025 EFL scheme. However, categorising samples are proving difficult to some of the OLs and interpretation of specific categories from the assimilated Regulation (EC) 2073/2005 (as amended) is a continuing problem – the NRL is seeking advice on this legislation to support the OLs on their test selection. The NRL participated in 13 EURL PTs from across all 6 EURLs. Performance was either satisfactory or good for 11 PTs. One PT was delayed, so was unable to perform PT and the other is awaiting EURL guidance.

The NRL organised a ‘Screening of Antimicrobial Resistant Bacteria in Food’ training workshop online and 26 delegates representing 10 OLs attended. The half-day event covered why AMR testing in foods is important, the methodology used and results from recent projects undertaken by the Food, Water and Environment Microbiology Service (FWEMS) laboratories on AMR. Feedback from participants was very good to excellent and all respondents stated it met their objectives.

Details of the proposed NRL activities for 2025 to 2026, and a timeline to achieve these complete this report.

Introduction

The UK’s National Reference Laboratory (NRL) service for food microbiology has been provided by the UK Health Security Agency (UKHSA) in compliance with assimilated Regulation (EU) 2017/625 for Official Controls, which was adopted as a UK Statutory Instrument when the UK left the EU on 31 December 2020. The Food Standards Agency (FSA) is the UK’s Central Competent Authority for food microbiology and has a Memorandum of Understanding (MoU) with UKHSA to hold responsibilities as the NRL in the following 6 areas: Listeria monocytogenes, coagulase-positive staphylococci, Escherichia coli (including Shiga toxin-producing Escherichia coli, STEC), Campylobacter, Salmonella and antimicrobial resistance (AMR). UKHSA has been the NRL for these activities for FSA since 2011 and will continue under the current agreement for a further 2 years, until March 2027.

This report describes the 7 core functions of the NRL service carried out between April 2024 and March 2025. Table 1 details the core functions and activities described in this annual report.

Table 1. UKHSA NRL Core Functions, April 2024 to March 2025

Core function	Description
1	Secretariat services
1.a	Disseminate information or advice from international organisations to FSA, OLs and other UK laboratories in a timely and effective manner
1.a	Produce and circulate quarterly newsletters to FSA, OLs and other UK laboratories
1.a	Co-ordinate the OL User Day to update UK OLs and other relevant UK laboratories of the NRL core functions
1.b	Prepare and carry out an audit regarding the OL’s capabilities and requirements
1.b	Review content of the UK Food Examiner Register
1.b	Continue liaison meetings with APHA for AMR, Campylobacter and Salmonella
1.c	Liaise with CEFAS for E.coli and Salmonella in shellfish activities
1.c	Liaise with Campden BRI to discuss and implement challenge testing activities
1.d	Provide regular updates to the FSA on NRL activities by producing monthly reports
1.d	Produce and submit annual report to the FSA on NRL activities for 2024 to 2025
1.e	Arrange quarterly meetings with FSA and FSS
1.f	Maintain and update the NRL web content on the UKHSA website
2	Advice and representation within the UK and internationally
2.a	Provide impartial expert advice to FSA, OLs and other UK laboratories, upon request
2.b	Represent the UK at relevant international meetings and working groups; consult FSA prior to meetings and submit an internal report after attendance of meetings
2.c	Attend training workshop at international organisations, where relevant and after successful applications
2.d	Liaise with FSA in matters concerning testing capabilities
2.e	Keep abreast of methodology developments and advise FSA and OLs (for example, AMR in Listeria spp from food literature review)
2.g	Participate in the BSI AW/9 microbiology committee
2.g	Participate in Working Group to revise the ISO/TS 13136:2012 (PCR detection of STEC) and other working groups where appropriate
3	Research and development, including production of standard operating procedures, codes of practice and guidance documents
3.a	Maintain UK food method list on NRL website
3.a	Produce an AMR SOP in food
3.a	Draft a manuscript for peer-review summarising multiple-year of OL performance of the EFL PT scheme
4	Compliance assessment through audits and ring trials
4.a	Ensure consistency and quality of testing approach applied by UK OLs and support where necessary
4.b	Liaise with FEPTU and monitor OL’s comparative testing performance and assist OLs in the implementation of corrective measures
4.b	Evaluate OL’s performance using trend analysis and report appropriately to the FSA
4.c	Co-ordinate the participation of OLs in international method validation studies and other initiatives and report to FSA
4.d	Participate as UK-NRL in proficiency tests and method validation studies organised by the EURL (where available) and report to FSA
4.e	Organise Teams or classroom-based workshops for UK OLs, dependent on the 2019 audit (1.b) and OL needs
4.e	Organise a practical workshop for UK OLs, dependent on the 2019 audit (1.b) and OL needs
4.g	Analysis and publication of the 2023 OL capability and capacity audit
5	Co-ordination within the UK of international initiatives
5.a	Support the food aspect of the EU-wide AR monitoring (Decision (EU) 2020/1729), liaising with FSA, OLs, relevant Reference Laboratories and APHA.
5.a	Provide information regarding Whole Genome Sequencing when requested from the EURLs, and participate in any related workshops, proficiency testing, training and guidance documentation, where necessary
5.a	Participate in training opportunities provided by international organisations
6	Communication of results and data use
6	Communicate with FSA of results and data use, when required
7	Incident management
7	Perform defined work when requested by FSA for incident management, with joint agreement and where appropriate

Core Function 1. Secretariat services

Dissemination of information from international organisations

The NRL sources relevant information from the 6 EURLs and other international organisations, such as:

• the EU Commission
• World Health Organization
• CODEX
• European Food Safety Authority (EFSA)
• European Centre for Disease Prevention and Control (ECDC)
• Zenodo (the EU’s open research science repository)

This information is either through direct communication or through regular monitoring of their websites. Depending on the content, updates are then cascaded to the appropriate personnel and stakeholders, for example:

• OLs
• FSA
• FSS
• UKHSA Epidemiology and Reference Units
• Scottish Reference Laboratories
• Animal and Plant Health Agency (APHA)
• Agri-Food and Biosciences Institute (AFBI)
• Centre for Environment, Fisheries and Aquaculture Science (CEFAS)

These communications are summarised below and more details can be found in the monthly activity logs, which are listed in the Annexe. Information concerning meetings, training, proficiency tests (PTs) and ISO standards is incorporated into other relevant sections of this report. The E. coli, AMR and Salmonella EURLs’ work programmes have been communicated to the UK NRL, whilst the other 3 EURLs’ programmes have not been made available.

In addition, the NRL reviews information produced from UK stakeholders, such as the FSA Link platform, UK Accreditation Service (UKAS) newsletters and UKHSA publications, such as the UKHSA Health Protection Report. Information regarding import control data, consultations on legislation, research and development reports and public health guidance is disseminated to OLs and relevant NRL colleagues.

General information disseminated

The NRL received 10 CODEX newsletters from the Department for Environment, Food and Rural Affairs (Defra) in this reporting year, which were reviewed and circulated to relevant colleagues where necessary. Invitations of relevant conferences were also received, including the 23rd Genomics and Proteomics conference, the 7th congress of the European Association of Veterinary Laboratory Diagnostics and Campden BRI’s Hot Topics in Food Microbiology.

There was further correspondence concerning the Border Target Operating Model (BTOM) and relevant webinar invitations that were either sent to the NRL or otherwise identified. These were shared with relevant and interested colleagues.

The NRL received the EU One Health Zoonoses 2023 Report from an EURL, and this was further disseminated. The AR EURL sent information concerning a call for experts to the ESCMID plasmid research working group and this was also forwarded to relevant known groups. In January 2025, Regulation (EU) 2025/179 was published, which required Member States to collect and transmit molecular (whole genome sequencing, WGS) data related to epidemiological investigations of food-borne outbreaks of L. monocytogenes, Salmonella enterica, E. coli and Campylobacter jejuni and C. coli to the EU One Health system. This will apply from 23 August 2026, and the NRL informed FSA of this regulation.

Antimicrobial resistance

EURL emails concerning their planned activities for 2024 to 2025, external training courses and their annual newsletter were received and distributed as appropriate (see Annexe).

Campylobacter

The UK NRL updated contact details on the EURL website at the request of the EURL.

Listeria

There have been 2 Rapid Outbreak Assessments in this period, produced by EFSA/ECDC: Prolonged multi‐country outbreak of Listeria monocytogenes ST1607 linked to smoked salmon products, EFSA and Prolonged multi‐country outbreak of Listeria monocytogenes ST173 linked to consumption of fish products, EFSA. These were distributed to stakeholders through the quarterly newsletters. The NRL also received and responded to a query from an OL regarding Listeria testing.

An amendment to Regulation (EC) 2073/2005, microbiological criteria for foodstuffs, was published on 20 November 2024 as Regulation (EU) 2024/2895, as regards Listeria monocytogenes. This amendment will tighten existing controls for food businesses that cannot provide assurance that L. monocytogenes will remain below 100 colony-forming units per gram (cfu/g) throughout shelf-life. The current requirement is for these businesses to demonstrate absence of L. monocytogenes in 25g of ready-to-eat food at the end of production. In contrast, the amendment will extend this requirement of absence in 25 g to apply throughout shelf-life where FBOs cannot assure growth will be under 100 cfu/g. This will apply in the EU from 1 July 2026. However, in the UK, this will currently only affect Northern Ireland (under the Windsor Framework) and FBOs that trade with the EU, especially where they are exporting products to the EU. The FSA has not yet published a decision regarding whether Regulation (EU) 2024/2895 will be assimilated into UK law in the future.

The NRL has been active in following the progress of this decision in the EU, clarifying the position in the UK and ensuring that OLs and other stakeholders are updated with developments.

STEC/E.coli

In December 2024, the EURL sent an overview of the planned activities for 2025, which the NRL logged. They also shared details about planned training sessions at the EURL, which are described under Core Function 2.

Salmonella

The EURL sent 4 quarterly newsletters by email, informing NRLs of their activities, which were forwarded to the FSA, the OLs and other relevant laboratories in the UK. The EURL newsletters can be found in the Annexe.

Related to core functions: 1.a, 1.c, 2.d, 2.e, 2.f.

Production of NRL quarterly newsletters

The NRL produces quarterly newsletters to disseminate information to OLs and other stakeholders regarding NRL activities and aspects of food legislation and food microbiology that may affect them. The newsletters, distributed in June, September and December 2024 and March 2025, are available in the Annexe.

Related to core functions: 1.a, 2.d, 2.e, 2.f

Co-ordination of the 2024 OL User Day

The NRL User Day was held on 30 September 2024 and was organised as a hybrid event with 21 participants meeting face-to-face at Colindale. Attendees had the opportunity to exchange information, share experiences and engage in informal discussions between the sessions. A further 41 delegates joined online, with 62 participants overall, attending from 12 OLs, UKHSA’s Gastrointestinal Bacteria Reference Unit (GBRU), Food and Environmental Proficiency Testing Unit (FEPTU) and Clinical Teams, FSA and FSS, CEFAS, APHA and AFBI.

The day’s objective was to inform and update stakeholders of the NRL’s areas of responsibility. Presentations (see Annexe for agenda) included a summary of the main outputs from the NRL in the last year, UK epidemiology of GI pathogens, the PathSAFE programme for an environmental AMR surveillance system, the revised ready-to-eat (RTE) guidelines, the proposed change in Listeria monocytogenes legislative criteria, and rounding off with future activities of the NRL.

A feedback form was sent to attendees to evaluate and help improve future NRL events. The NRL received responses from 34% of the participants (of whom there were 21 respondents), and most found the content, slides and overall administration was very good or excellent. The length of the meeting and speaker’s pace scored a little lower, mostly receiving very good or good, and with 12 comments stating a little more time for discussion or fewer presentations would have been better. Positive comments received included “a good mix of attendees who asked good questions”, “No improvement needed in my opinion” and ”Good ratio of everything”.  All except one respondent reported they would recommend the User Day to their colleagues. Future workshop topics that participants are interested in include ‘categorising food and interpretation of EC 2073/2005’ (16 participants), ‘measurement of uncertainty’ (10 participants) and ‘witness statements’ (8 participants). The NRL distributed and made available presentations on request.

Related to core functions: 1.a, 1.b, 1.c, 2.a, 2.d, 2.e, 2.f, 6.l

Figure 1. NRL User Day delegates 2024, photographed by the memorial bench of Dr Jim McLauchlin

Figure 1 shows 21 NRL user day delegates sitting and standing by a bench.

2023 Audit: official laboratories’ capabilities and requirements

As part of the contract with FSA to monitor and support the UK OLs’ capabilities, the NRL launched a fourth audit in November 2023 to all UK OLs. Questions used in this audit were predominantly unchanged to compare results from the 3 previous audits and evaluate change. The online survey tool, SelectSurvey, was used to ask UK OLs details of Food Examiner (FE) status, schedule of tests performed, participation in proficiency testing (PT) schemes and problem areas where OLs would like support. All 14 OLs responded, although responses to individual questions were missing from one or 2 OLs.

The audit revealed that, although the number of laboratories has remained stable since the 2016 audit, numbers of Food Examiners have decreased from 55 to 39 between 2013 and 2023. Overall, testing capabilities of the UK OL network has remained stable, according to the EU microbiological criteria regulation (the assimilated Regulation (EC) 2073/2005 (as amended)). There is good testing capability for Listeria and Salmonella in line with the Food Safety Criteria (FSC), with reduced capability for only a few FSC. For example, only a small number of laboratories are accredited for Cronobacter testing of dried products intended for infants below 6 months of age (only 1 of 14 labs holds accreditation) and histamine detection in fish (4 of 14). Reasons for the low coverage of these tests may include that they are highly specialised tests or that they are rarely requested in the UK. This makes maintaining accreditation and competence in OLs difficult to attain and justify. Furthermore, there are no OLs capable of detecting the presence of staphylococcal enterotoxins in cheeses, milk powder and whey powder. In contrast, detection of Shiga toxin producing E.coli (STEC) in sprouts (criterion 1.29) has continued to be implemented in additional OLs. Although added to the microbiological criteria over a decade ago, OLs are continuing to develop and implement this methodology as there is a growing need for STEC in other matrices. The NRL has arranged training workshops to support the OLs in the development of this technique, which may also have contributed to the improvement in this area of capability. The NRL aims to support the OLs in implementing further tests, especially where there is a demand and need for them.

There is an increased uptake in PTs by the UK OLs, with participation ranging from across 2 to 11 different PT schemes, including the FEPTU European Food Microbiology Legislation (EFL) Scheme, which assesses competence and quality when generating and interpreting laboratory results in line with assimilated EU legislation. Only half the OLs perform shelf-life and challenge testing, which has remained stable since 2016. This complex area requires different procedures compared to routine microbiological testing of food and is thus difficult for OLs to include in their routine laboratory activities. Detection of viruses and antimicrobial resistant (AMR) bacteria in the food chain are only carried out in a small number of UK laboratories, but as the One Health approach is adopted, AMR testing may be required or requested more frequently in the future, and the OLs may need to consider these approaches.

To continually improve and meet the needs of the OLs, the survey included questions regarding NRL activities and support. Six OLs would like to see smaller discussion groups at the annual User Days to facilitate cross-communication. Topics suggested for more support from the NRL include ‘validation or verification of ISOs’, ‘uncertainty of measurement’ and ‘interpretation of EC 2073/2005’, for which the NRL can organise future workshops or breakout sessions at the User Days. From the survey, the NRL identified some issues and areas of concern, along with associated recommendations for actions to address these.

See the full report.

Related to core functions: 1.b, 2.d, 2.e, 4.g.

Review content of the UK Food Examiner register

A Food Examiner register has been maintained by the NRL since 2014 to assist FSA to rapidly contact them for appropriate local support with incidents and investigations. In February 2025, the register was updated in response to a request from FSA.

Related to core functions: 1.b, 4.g.

Liaise with APHA regarding mutual NRL activities (Campylobacter, Salmonella and antimicrobial resistance)

The UK NRL for Food Microbiology (UKHSA) shares responsibilities with the UK NRL for Animal Microbiology (APHA) for Salmonella, Campylobacter and antimicrobial resistance (AMR). To help strengthen relationships and share information, regular liaison meetings are held to discuss activities organised by the EURLs. Since EU Exit, participation in these meetings has expanded to include AFBI for Northern Ireland. Meetings were held remotely in May and November 2024.

Related to core functions: 1.b, 4.c, 5.a.

Liaise with CEFAS for overlapping NRL activities

CEFAS is the UK NRL for foodborne viruses and bacteriological contaminants of shellfish and liaises with the E. coli and Salmonella EURLs. As mutual activities, such as PT participation and meeting attendance, are shared with the UKHSA and APHA NRLs, relevant information from EURLs is shared with CEFAS colleagues.

Related to core functions: 1.a, 1.c, 4.c, 5.a.

Liaise with Campden BRI to discuss and implement challenge testing activities

Campden BRI has expertise in a wide variety of challenge testing approaches and their experts sit on working groups for relevant ISO Standards. Therefore, the NRL arranges yearly meetings, and a Teams meeting was held in June 2024 to discuss the ISO Standard 20976 series on challenge tests in food, EURL documents on shelf-life determination, participation in EURL PTs and other relevant guidance.

Related to core functions: 1.c, 2.e, 4.c, 5.a.

Provide regular updates to Food Standards Agency

Quarterly meetings were held between NRL representatives and FSA colleagues (17 June 2024, 3 September 2024, 11 December 2024, 4 March 2025) to discuss objectives’ progress, difficulties met, and future or new activities (see Annexe for minutes). Monthly reports were also submitted electronically to the FSA, listing NRL activities (see Annexe). This comprehensive annual report provides a summary of all the NRL activities within the 12 month period and is published on the NRL page of the GOV.UK website.

Related to core function 1.d, 1.e, 6.a, 6.d, 6.k.

NRL web content

General information about the NRL, expert witness information and contact details are on GOV.UK. It also hosts the NRL annual reports, completed OL audit reports and a list of 16 NRL-relevant UKHSA standard methods (last accessed 8 August 2025). To obtain these methods, OLs and other relevant laboratories can contact the NRL, who can provide the most current versions available. This process allows the NRL to monitor how frequently methods are accessed and, by directly contacting theses laboratories, to understand the users’ needs. In this review period, the NRL has received 13 separate requests for 34 methods and has sent them to 3 OLs, 2 private UK laboratories and 4 overseas state laboratories.

To find the NRL web page, OLs and other stakeholders are advised to use a search engine and type the search term ‘fwe nrl’, which usually results in the NRL web page appearing as the top search result.

Related to core functions: 1.a, 1.f, 3.a.

Core Function 2. Advice and representation within the UK and internationally

Provide impartial advice to FSA, OLs and other UK laboratories

The NRL receives requests for expert advice from stakeholders ranging from small food businesses to FSA and international institutes. These are responded to by NRL colleagues, and where further expertise is required, forwarded to relevant experts. Requests received between April 2024 and March 2025 are summarised below, and more detail can be found in the monthly logs (see Annexe).

Over 20 queries concerning method advice and support, the interpretation of results or implications of testing were received by the NRL from OLs, other departments of UKHSA, FSA, an EURL and other overseas laboratories, and undergraduates.

The NRL received at least 4 requests to test products from FBOs, which were forwarded to the geographically closest OL to the FBO.

There were 5 queries relating to NRL training events, workshops and conferences from an OL, FSA, 2 international countries and a private UK laboratory.

The AR EURL sent a survey in January 2025 to capture the methods and media used to screen and identify AMR isolates pertaining to the Commission Decision (EU) 2020/1729, for the monitoring and reporting of AMR in zoonotic and commensal bacteria. The NRL collated and submitted information through the online survey.

An OL query was received regarding the revised UKHSA Guidelines for assessing the microbiological safety of ready-to-eat foods placed on the market, which were published in September 2024 by FWEMS.

Related to core functions: 2.a, 2.d.

Representation at relevant international meetings and submission of meeting reports

Since leaving the EU, the UK NRL is able to participate in EURL proficiency testing and attend the PT sections of their network annual meetings. However, although in-person attendance is offered, travel to the meeting locations cannot be justified for the relatively short duration of these sessions and therefore NRL representatives attend remotely. On this basis, UK NRL received invitations for, and attended, a special webinar for the PTs organised by the AR-EURL and the PT session of the Escherichia coli (incl. STEC) EURL meeting.

For updates on the remainder of the EURL workshops, NRL checks regularly on EURL websites for workshop reports (where available) and shared presentations and produces reports on these where available. Reports for the AR, E.coli, Listeria, Salmonella and Campylobacter meetings were sent to FSA and relevant NRL colleagues (see Annexe).  Presentations from the coagulase positive staphylococci EURL meeting are held on restricted access webpages, which the UK NRL is no longer able to access.

Where available, agendas for the meetings were also forwarded to the FSA as they were received (see Annexe).

Related to core functions: 1.a, 2.b.

Attend training workshops at international organisations

In February 2024, the STEC EURL circulated an Expression of Interest (EoI) request to attend training in 2024. The NRL submitted 2 applications, and both were accepted by the EURL. One applicant attended a 5 day training on the ‘Detection of STEC in food matrices according to the ISO TS 13136:2012 and the characterization of the isolated STEC strains’ in Rome, Italy at the STEC EURL in April 2024. Feedback from the attendee was good and the participant gained skills regarding PCR technologies.

The other applicant was registered to ‘Identification and characterisation of the different groups of pathogenic E. coli’ training in September 2024 but was unfortunately unable to take up the opportunity.

The AR EURL invited NRLs to a 4-day training on Oxford Nanopore sequencing, where the UK NRL successfully secured one place for the 2 day ‘wet-lab’ training at the EURL in Kings Lyngby, Denmark. Held in December 2024, the first and last days were ran as webinars to maximise attendance. Consequently, one NRL scientist also attended the online webinars. Feedback from the full UK attendee noted that it “covered both theoretical and practical aspects of the technology, enabling a comprehensive understanding of the sequencing process” and provided awareness of user-friendly tools and techniques.

UK trainees reported that they would recommend the courses they attended.

The inter EURLs working group for WGS holds annual training workshops for EU Member State NRLs. Whilst the UK NRL is unable to participate, extensive material relating to this event can be found on the EU platform, Zenodo.

In January 2025, the STEC EURL sent out an EoI invitation to attend their training in 2025. The UK NRL submitted 2 EoIs to attend the ‘detection of STEC in food’ workshop, one of which were accepted.

Related to core functions: 2.c, 2.e, 5.a.

Liaise with FSA concerning testing capabilities

Correspondence concerning testing capabilities, including method development queries and feedback on the National Monitoring Plan was mentioned above, under ‘Provide impartial advice to FSA, OLs and other UK laboratories’. Results from the 2023 OL audit were also shared and discussed with FSA, which included testing capabilities (under ‘2023 Audit: official laboratories’ capabilities and requirements’).

In April 2024, FSA hosted an online ‘Food and Feed Laboratory Workshop’, to which all UK NRLs and OLs were invited. The UK NRL prepared a pre-recorded slide-set on how the EFL scheme is used to assess the OLs’ performance and attended the workshop. There were 2 breakout discussion sessions addressing collaboration between NRLs and OLs and identifying skill gaps in laboratories, with good engagement from participants at the meeting.

There was a specific request for information from FSA in November 2024, as the UK underwent an EU audit on dairy controls including microbiological testing. The NRL sent information to Defra concerning UK’s current testing capability, OLs’ performance in relevant PTs, and the STEC practical training given to OLs. The FWEMS Lead Microbiologist represented the NRL at the remote technical meeting and findings from the EU audit indicated that laboratory testing was adequate.

Related to core functions: 2.d.

Keep abreast of methodology developments

The NRL participates in national and international meetings to keep abreast of emerging issues and developments for food microbiology. These included 2 FW&E Food Examiner sessions in June 2024 and March 2025, focusing on FW&E project and survey findings and Witness Statement writing, respectively; several FSA Food for Thought webinars on a variety of topics; and the Food and Waterborne Infections session of the 2024 ESCAIDE conference, held as a hybrid event. The NRL attended the 23rd conference on Genomics and Proteomics, held in West London in June 2024, which included a presentation on the use of a MALDI-ToF approach to determine subtyping of food pathogens, giving Salmonella as an example. The FEPTU international meeting was held online in October 2024 and included an ISO update, the microbiological safety of plant-based alternatives to meat and dairy products and the challenges of recent FEPTU PTs.

In November 2024, a workshop entitled ‘Advancing STEC diagnostics’ was jointly organised by the FSA, the Chilled Food Association and the Quadrum Institute to bring together industry, public and government authorities to address the urgent need in the industry to conduct accurate, timely and economical testing for STEC. Representatives of the NRL attended and participated in open discussions which resulted in 4 proposed workstreams:

• sampling for STEC
• diagnostic testing for STEC
• standardisation in test result reporting and mechanisms for data sharing
• developing frameworks for test result interpretation and actions

The NRL regularly reviews international organisations’ websites, such as the EURLs, Zenodo, CODEX and ISO for new methods or developments, and these are shared to relevant colleagues to evaluate whether they should be incorporated into the UK microbiology testing portfolio.

In January 2023, the FSA requested the NRL to perform a literature review on ‘AMR in Listeria monocytogenes and other Listeria spp. in food’. After an initial literature search and draft, the NRL updated the literature search in this reporting period, and a revised draft is being produced.

Related to core functions: 2.e, 2.f.

Participation in the BSI AW/9 microbiology committee and other working groups

There were 2 meetings of the BSI AW/9 committee that the UK NRL attended remotely, in May and November 2024. Relevant ISO Standards to the NRL were reviewed at these meetings. The NRL can view and comment on draft and final draft ISOs (for example, those at NP, DIS and FDIS stages of development) through the BSI AW/9 portal throughout the year. Therefore, the NRL submitted comments for the following draft standards under the ISO/TC 34/SC 9 committee, Microbiology of the Food Chain:

• ISO 13136-1 (Detection and isolation of STEC)
• ISO 13136-2 (Characterisation of STEC isolates)
• ISO 22174 (PCR general requirements and definitions)
• ISO 16140-2 amendment (revising calculations and including a commercial sterility testing protocol)
• ISO 6887-1 amendment (use of larger portion size)
• ISO 16140-3 amendment (verification of validated identification methods)
• ISO 16140-4 amendment 2 (single-laboratory validation of identification methods)
• ISO 16140-7 (validation of identification methods)
• ISO 6579-4 (Identification of monophasic Salmonella Typhimurium by PCR)

In addition, there was a call for data to compare the pour plate and spread plate methods for ISO 11649-2 (Glucuronidase positive Escherichia coli enumeration) and the FWEMS/NRL participated in this exercise and submitted data in January 2025.

A representative of the UK NRL is an active member of the CEN/TC 463/WG2 expert working group for the revision of the ISO TS 13136 standard (PCR detection of Shiga toxin-producing Escherichia coli) and participated in meetings in June, October and December 2024.

Related to core functions: 2.e, 2.f, 2.g.

Core Function 3. Research and development, production of standard operating procedures, codes of practice and guidance documents

Maintain food methods list on NRL webpage

On the NRL webpage there is a list of methods and guidance documents that laboratories can request using the NRL contact details. This allows audit of the methods and ensures the most up-to-date versions are given. There are 16 relevant documents which are listed in Table 2. The methods are based on ISO standards and UKHSA in-house procedures and assist OLs to comply with the requirements of assimilated Regulation (EC) 2073/2005. In addition, other UKHSA standard operating procedures (SOPs) are available to OLs upon request.

Table 2. List of standard methods archived on the NRL website, March 2025

Document number	Title
FNES63	Determination of pH in food and water samples
FNES67	Determination of water activity in food
FNES8 [F12]	Enumeration of coagulase positive staphylococci (Staphylococcus aureus and other species)
FNES26 [F2]	Preparation of samples and dilutions, plating and sub-culture
FNES3 [F8]	Enumeration of β-glucuronidase positive Escherichia coli: Pour plate method
FNES22 [F19]	Detection and enumeration of Listeria monocytogenes and other Listeria species
FNES131	Enumeration of β-glucuronidase positive Escherichia coli – TEMPO most probable number technique
FNES16 [F13]	Detection of Salmonella species
FNES15 [F21]	Detection and enumeration of Campylobacter species
FNES4 [E1]	Detection and enumeration of bacteria in swabs and other environmental samples
FNES18 [Q4]	Guidance on Public Health response: involvement of UKHSA Food Water and Environmental Microbiology laboratory staff in the investigation of outbreaks of food or waterborne disease
FNES61 [Q3]	Verification and validation of methods
FNES66	Measurement uncertainty in testing
FNES144	Detection and isolation of Shiga toxin-producing E. coli
FNES45	Preparation of positive control DNA for use in real-time PCR assays for foodborne pathogens
FNRLW1	FEPTU/NRL EFL scheme – monitoring performance protocol

The UK NRL is responsible for the authorship and review of 2 general methods for the Food, Water and Environment Microbiology Service (FWEMS):

• Verification and Validation of Methods (FNES61)
• Measurement Uncertainty in Testing (FNES66)

Both of these were due for routine review in 2024, and this was performed by the NRL. Two impact assessments were completed by the NRL for relevant external documents:

• the UKAS publication M3003, Edition 5 September 2022: The Expression of Uncertainty and Confidence in Measurement
• the ISO Standard 17468:2023 – Technical requirements and guidance on establishment or revision of a standardised reference method

In addition, the NRL reviews the above methods and other relevant FWEMS methods and external documents when they are being revised.

Related to core functions: 1.a, 1.e, 3.a.

Produce a Standard Operating Procedure for the detection of AMR in food

In October 2023, the FSA asked the NRL to produce an SOP for the detection of antimicrobial resistant (AMR) E. coli in food, including shellfish, to ensure there is a protocol that the UK could use in the future. Therefore, in March 2024, the NRL produced a draft document, FNES136, ‘Detection of presumptive AMR E.coli in food’ and submitted this to FSA. Subsequently, additional information was added to describe techniques for enumeration of AMR E. coli, and at the time of writing, the SOP is undergoing internal quality checks before publication.

Related to core functions: 2.d, 3.a.

Report of multi-year OL performance in the EFL scheme

This activity has been delayed due to other work priorities and NRL staff changes.

Related to core functions: 3.a, 4.b.

Core Function 4. Compliance assessment through audits and ring trials

OL participation in the European Food Microbiology Legislation Proficiency Testing Scheme

The NRL organises relevant comparative testing through proficiency studies to monitor, assess and follow-up performance of official laboratories as required by the assimilated (EU) Law for official controls from European Regulation (EC) 625/2017. The European Food Microbiology Legislation (EFL) External Quality Assessment Scheme is provided by the UKHSA Food and Environmental Proficiency Testing Unit (FEPTU) and is based on the requirements of assimilated Regulation (EC) 2073/2005 for the microbiological criteria for foodstuffs which remains relevant to UK official controls.

The NRL supports participation of this scheme, which allows direct performance comparison across the OL network, whilst acting independently from the scheme organisers. Results are coded (see Annexe for distribution reports), and the NRL monitors performance of each laboratory and invites laboratories to seek assistance from the NRL when experiencing difficulties.

2024 to 2025 EFL Scheme analysis

In January 2024, the NRL invited all UK OLs for food microbiology to re-register to the EFL scheme for the 2024 to 2025 scheme year. Registrations were received from all 14 OLs to receive samples for at least one distribution, with 13 laboratories registering to receive all 4 distributions. Table 3 summarises the samples for the 2024 to 2025 scheme and the performance of laboratories that carried out the examinations.

Simulated food samples with a product description were distributed between May 2024 and January 2025, where participating OLs decided which food categories from the process hygiene and food safety criteria in assimilated Regulation (EC) 2073/2005 the food is tested under, resulting in a score. Other parameters scored are examination name, number of samples from a batch required for compliance, the microbiological result and a relevant conclusion. Laboratories are awarded marks where data is entered and can achieve a maximum of 8 marks. One or more examinations per sample may be applicable for compliance, and there are 3 samples per distribution. Figure 2 shows the median laboratory scores for distributions from the 2023 to 2024 (EFL63 to EFL66) and 2024 to 2025 (EFL67 to EFL70) schemes.

This year, the median percentage scores from submitting laboratories for each distribution were 95.00%, 94.79%, 97.50% and 97.87% respectively. For both scheme years, OL performance has been shown to be significantly above the 70% threshold (red line, Figure 2) that the NRL and FEPTU have assigned for follow-up action.

Figure 2. Median OL scores for EFL distributions from 2023 to 2025

Table 3. Overview of performance of the 2024 to 2025 European Food Microbiology Legislation Scheme

Sample code	Brief sample details	Required examinations	OLs achieving over 70% of the maximum possible score [note 1]
Distribution EFL67 Meat foods
EFL199	Raw chicken burger made with herbs and seasoning, sampled from a local butcher during product’s shelf-life	Salmonella spp.	12/13
EFL200	Japanese sashimi made with raw beef mixed with a garlic soy-based sauce, sampled during the shelf-life from a local supermarket	L. monocytogenes enumeration Salmonella spp.	10/13 12/13
EFL201	Mince lamb meat sampled at the end of the manufacturing process	Aerobic colony count Escherichia coli	12/13 13/13
Distribution EFL68 Dairy foods
EFL202	Home-made butter made from raw cow’s milk, purchased from a local artisan farm shop during the shelf-life	L. monocytogenes enumeration Salmonella spp.	14/14 14/14
EFL203	Dried infant milk formulae for babies below 6 months, sampled at the end of the manufacturing process	Enterobacteriaceae (detection) Cronobacter spp. Presumptive Bacillus cereus	Not scored [note 2] 2/10 [note 3] 14/14
EFL204	Brie made from milk that has undergone pasteurisation, sampled during the manufacturing process	L. monocytogenes detection Escherichia coli Coagulase-positive staphylococci	13/14 14/14 8/13 [note 4]
Distribution EFL69 Ready-to-Eat foods
EFL205	Steak tartare made with minced raw beef steak mixed with raw egg yolk, onions, and spices. Shelf life of less than 5 days, product sampled whilst on the market	L. monocytogenes enumeration Salmonella spp.	13/14 14/14
EFL206	Whey protein powder made from milk. Sampled at the end of the manufacturing process	Enterobacteriaceae Coagulase-positive staphylococci	13/14 14/14
EFL207	Ready to eat pre-cut tropical fruit salad with no additives and shelf-life of less than 5 days (pH 5) sampled at the end of the manufacturing process	L. monocytogenes detection Escherichia coli	Not scored [note 5] 13/14
Distribution EFL70 Miscellaneous foods
EFL208	Unsalted garlic butter made from raw milk. Sampled at the farm’s shop before product is put on the market for sale	L. monocytogenes detection Escherichia coli	12/12 10/12
EFL209	Italian salami made with mixed spices, sampled from the fridge of a local delicatessen whilst on sale	L. monocytogenes enumeration Salmonella spp.	11/13 11/11
EFL210	Mechanically separated meat sampled at the end of the manufacturing process	Aerobic colony count Escherichia coli	12/13 13/13

Note 1: Number of laboratories achieving over 70% compared to the total laboratories participating in the examination of the sample. A maximum possible score is 8 marks per examination. Those that did not return any data or did not examine samples were not included in this table.
Note 2: A performance issue was identified due to the low level of organisms within the Enterobacteriaceae group; therefore, this examination was not scored.
Note 3: Ten laboratories indicated the requirement to examine Cronobacter spp. in parallel with Enterobacteriaceae for this sample type.
Note 4: Thirteen laboratories indicated the requirement to examine Coagulase-positive staphylococci, and 6 laboratories additionally indicated that due to the levels of the S. aureus in this sample (more than 10⁵ cfu/g), a Staphylococcal enterotoxin test would be required for compliance.
Note 5: Due to the complexity of the requirements for L. monocytogenes under assimilated Regulation (EC) 2073/2005 (as amended), the organisers of the scheme did not score the examination of L. monocytogenes for this sample.

An improvement was observed in the number of samples for which the appropriate tests were identified for compliance with the statutory criteria. Of the 12 samples distributed, 8 samples had all examinations correctly identified by all laboratories returning a result for that sample (compared to 4 samples last year). Of the remaining 4 samples, one had all its examinations correctly identified by 93% of submitting laboratories, 2 samples by 85% of submitting laboratories and one sample by 71% of submitting laboratories.

The examination requirements for infant milk formulae against the micro-criteria continues to challenge OLs, although some improvements are observed compared to results from a previous identical sample. Sample EFL203, (Table 3) required testing against criterion 2.2.9 for Enterobacteriaceae. Fourteen laboratories correctly identified this criterion, and 7 laboratories performed microbiological examination. This is compared to 12 (out of 14 participating) laboratories identifying this for sample EFL197 (from the 2023 to 2024 scheme) and 8 laboratories performing microbiological examination under the same criterion.

Footnote 9 of food category 2.2.9 requires parallel testing of Enterobacteriaceae and Cronobacter spp. 10 OLs identified the requirement for both examinations and this compares to 8 OLs identifying both organisms for sample EFL197.

This product is problematic, as the 2 examinations above are required to be selected from the microbiological criteria, but sampling occurs at only one stage of the product’s life. Food safety criterion 1.24 requires the absence of Cronobacter spp. in dried infant formulae intended for infants below 6 months during its shelf life whereas the process hygiene criterion 2.2.9 requires the absence of Enterobacteriaceae in the same product type at the end of its manufacturing process. Both criteria have identical footnote statements with regards to parallel testing of Enterobacteriaceae and Cronobacter spp. and the scheme design requires the selection of an appropriate microbiological criterion based on the sample description provided. It remains unclear which food category should be selected for Cronobacter spp. when sampled at end of manufacture, and the number of samples to test, due to the ambiguous footnotes related to categories 1.24 and 2.2.9. For these reasons, the selection of either criterion to examine Cronobacter spp. was accepted as being correct for sample EFL203.

A sample of pasteurised brie sampled during the manufacturing process required examination of coagulase positive staphylococci (CPS) against process hygiene criterion 2.2.4 (EFL204, Table 3). Thirteen OLs identified the CPS test and 8 reported a correct result over 10⁵ cfu/g, a level that triggers further testing for enterotoxin. Six OLs additionally indicated this in their reporting. Five OLs reported a count outside the expected range; 3 of those reported a high censored value (that is, greater than the laboratory’s upper detection limit for this test, for example, more than 30,000), but below 10⁵ cfu/g. Therefore, these labs did not identify the requirement for enterotoxin testing and were reminded of the importance of using a method that ensures the reporting of this organism to the correct level for compliance.

Two samples (EFL205 and EFL207), both from the distribution focused on ready-to-eat foods, had mixed results for the legislative requirements for Listeria monocytogenes. A sample of steak tartare with a shelf life of less than 5 days and sampled at market (EFL205, Table 3) required examination against category 1.3 (for RTE foods unable to support the growth of L. monocytogenes). Whilst 8 OLs indicated this correctly, 5 OLs incorrectly indicated examination against category 1.2 for foods able to support the growth of L. monocytogenes. Footnote 8 of category 1.3 states ‘…products with a shelf life of less than 5 days shall be automatically considered to belong to this (1.3) category’. Laboratories are reminded of statements in the footnotes associated with the food categories of relevance.

EFL207, a ready-to-eat pre-cut fruit salad also with a shelf life of less than 5 days but sampled at the end of its manufacturing process, was indicated to require L. monocytogenes by 8 OLs, of which 6 stated this would be part of food category 1.2 and 2 as part of food category 1.3. With a shelf life of less than 5 days, this food would automatically belong to food category 1.3 (according to associated footnote 8). However, the stage at which this sample was taken (that is, end of manufacturing) means that it would not be required to comply with 1.3. The requirements for L. monocytogenes under the legislation are complex and there appears to be no provision for the examination of L. monocytogenes for a product of this description. The examination of L. monocytogenes was therefore not scored.

The difficulty of categorising samples in relation to Salmonella testing was observed for some samples this year. Several food types (and therefore categories) described in Chapter 1 of the legislation require Salmonella testing, but with some differences in the testing volume and interpretation of results. Laboratories indicated a range of food categories for a Salmonella test for the same sample. Category 1.4 for the examination of Salmonella for sample EFL205, described as a steak tartare made with minced raw beef steak mixed with raw egg yolk and sampled at market, was correctly indicated by 11 OLs. However, 3 OLs selected other food categories for Salmonella (FSC 1.5, 1.8 and 1.15) due to the similar food descriptions stated in them.

Similarly, sample EFL209, an Italian salami sampled at the point of sale (Table 3) was also categorised differently by different OLs. Whilst 6 OLs correctly identified category 1.8 (meat product intended to be eaten raw), categories 1.4 (3 OLs) and 1.6 (2 OLs) for minced meat and meat preparations were incorrectly indicated. The NRL is seeking advice on the definitions of some food types and their categorisation within the micro-criteria to further advise and educate laboratories on their test selection for compliance to the legislation.

The NRL observed fewer examinations with missing entries resulting in a reduction in the overall score. Five examinations (out of 25) did not have their information completed by the submitting laboratory. These laboratories were awarded marks which resulted in a score of less than the maximum available marks (that is, 8). This compares to 7 out of 25 incomplete examination entries last year. As observed in previous years, incomplete entries are often seen for methods that are known to be performed less frequently or by fewer OLs. This was the case this year for the examinations of Enterobacteriaceae detection and Cronobacter spp. However, this year, the 3 remaining examinations where a laboratory did not submit a result in full were all for the enumeration of Listeria monocytogenes. The NRL observes this type of anomaly year after year and this is discussed further in the next sub-section, monitoring of overall performance.

To gain all available marks for an examination and improve assessment and evaluation of performance, it is important for laboratories to make themselves aware of the marking scheme when completing the submission form, check and confirm entries and ensure that the completion of scored parameters is not overlooked.

Monitoring of overall performance, trend and bias for EFL results

The NRL performs a ‘register and return’ analysis in accordance with the NRL’s OL performance monitoring protocol, on OLs who register to receive a distribution but subsequently do not submit a result. On average, between 2014 and 2022, 3 OLs per year registered but did not submit a result for an entire distribution . This peaked to 5 OLs in the 2022 to 2023 scheme year but encouragingly declined to 2 OLs in 2023 to 2024. This year, only one OL had not submitted a result, for a single distribution. This OL then submitted results for the remainder of the scheme which it had registered to receive.

The NRL started performing trend and bias analyses for the results of this PT formerly last year, and this has continued to be analysed this year for the microbiological results of both enumeration and detection tests as well as overall sample results. Most examinations this year demonstrate performances of no concern, although anomalous results have been observed for the enumeration of Listeria monocytogenes. One laboratory did not perform microbiological examination of Listeria for 2 samples across 2 distributions but have performed Listeria examinations for other samples within the same distributions. Another laboratory also identified the requirement for L. monocytogenes enumeration for a sample but did not perform the microbiological examination on this sample, although they performed Listeria examination for another sample, also within the same distribution. Although the NRL’s performance monitoring protocol does not cover deviations specifically of this nature, there will be a continual monitoring of such anomalies from future results.

Samples processed from the EFL Scheme allow participating laboratories to maintain their knowledge of microbiological criteria and their application to foods at manufacture and on the market. The scheme not only provides a single suitable platform to assess microbiological proficiency, but also enables the demonstration of laboratory understanding to show compliance against legislative requirements, as laboratories test a variety of samples for official control. Decisions on testing should be based on fact, not assumption, and laboratories should refer to the FEPTU guide to scoring for more information. OLs are also reminded that the NRL continues to offer its support when experiencing any difficulties with testing, and both the NRL and the scheme organisers are available for assistance.

The NRL will continue to assess laboratory performance through proficiency testing and has invited all UK OLs to register for the 2025 to 2026 distributions of the EFL scheme.  All OLs are obliged to participate on request by the NRL and to adhere to assimilated Regulation (EU) 2017/625. Participation provides overall assurance of laboratory competence, identifies areas of weakness and highlights the need for further training as well as demonstrating compliance with laboratory quality standards and accreditation. OLs will also continue to have access to expert advice and support from FEPTU or the NRL.

Related to core functions: 4.a, 4.b, 4.c.

Participate as UK-NRL in EURL ring trials and other initiatives

Since EU-exit, the EU allows the UK to participate in proficiency testing and as the NRL is obliged to take part in external quality assessments made by international organisations since the Regulation (EU) 2017/625 was assimilated into UK law (UK SI 2019 No. 1481), EURL invitations to participate in PTs have been accepted. The EURL PTs provide the only way to obtain direct comparison with EU NRLs, which is a key factor to assure that the UK’s microbiological capabilities are appropriate to ensure good biosecurity for trade both in and outside the EU.

Thirteen distributions were received from across all 6 EURLs, and included tests for detection, enumeration, DNA sequencing and culture strain typing, challenge testing and subsequent analyses and interpretation. Table 4 lists these PTs and a summary of performance (see Annexe for EURL PT reports, where available).

In March 2024, the Campylobacter PT involving enumeration from chicken meat was received; when comparing with the other NRLs, one enumeration result from UKHSA was a log lower than the median value. However, the UK still attained an overall ‘good performance’ outcome for enumeration and excellent species identification, which included Campylobacter jejuni, C. coli and C. lari. The EURL also organised a WGS and cluster analysis PT: although the UK generated slightly inferior assembly quality control (QC) values (along with 2 other NRLs), the resulting allele calling was over the acceptance threshold, which resulted in satisfactory performance for sequence quality and analysis.

The AR EURL organised a PT to assess laboratory capability for confirmation and characterisation of presumptive MRSA isolates using multiplex PCR methods or WGS. This was to ensure member states (MSs) were prepared for the MRSA baseline survey in 2025. The UK NRL was invited to participate and demonstrated the satisfactory use of WGS to characterise MRSA and, along with most NRLs, achieved a good performance; only 10 results out of 2,106 possible results were incorrect, with an acceptable 0.47% deviation overall.

The STEC EURL arranged 2 detection PTs and one identification PT in this reporting year. In May 2024, the detection of STEC in cheese gave varied results in the 4 non-EU laboratories participating, but the UK NRL laboratory achieved satisfactory performance. The other STEC detection PT in spent irrigation water in October 2024 experienced severe customs delays, which resulted in the inability to recover any viable STEC from the PT samples. The UK NRL participated in the STEC identification and typing distribution (PT41) and preliminary analysis from the EURL indicates that the UK NRL matched 100% with the intended virulence genes from the 8 strains sent.

In May 2024, the CPS enumeration PT was distributed, and the NRL obtained good z-scores (calculated as comparable to the intended result). However, the UK is unable to compare results with other NRLs as the PT report is inaccessible to the UK.

Table 4. NRL participation in EURL ring trials, March 2024 to February 2025

Month received	Organism – test	Matrix or pure culture	Comments [note 1]
March 2024	Campylobacter:  enumeration and voluntary species identification	Chicken meat	Good performance for enumeration Excellent rating for species identification
March 2024	Campylobacter: WGS and cluster analysis	DNA extracts and pure cultures	Satisfactory sequence quality and sequence analysis
April 2024	MRSA: Staphylococcus aureus isolation, using PCR1 and PCR2 or WGS	Pure cultures	Good performance
May 2024	STEC: detection and isolation	Cheese	One laboratory satisfactory performance, other laboratory experienced cross contamination event
May 2024	CPS: enumeration	Shrimps	Satisfactory performance
October 2024	AMR AST for: - E.coli - Salmonella - Campylobacter	Pure cultures	- 0.5% deviation: satisfactory results - 0% deviation: satisfactory results - 0% deviation: satisfactory results
October 2024	Salmonella: detection	Fabric swabs	Did not detect Salmonella in 3 of 4 low level samples: awaiting EURL guidance
October 2024	Listeria monocytogenes: challenge testing	RTE vegetal matter	pH was high for day 14 data, but otherwise satisfactory performance
October 2024	Listeria monocytogenes: cgMLST typing	Pure cultures	Satisfactory performance
October 2024	STEC: detection and isolation	Spent irrigation water	UK Customs issues resulted in delayed receipt of PT: unable to participate
October 2024	STEC: typing and WGS analysis	Genomic sequences and pure cultures	Preliminary results: 100% match with intended virulence gene detection; did not participate in cluster analysis
October 2024	WGS for: - E. coli - Staphylococcus aureus - Enterococcus faecium or faecalis	Pure cultures	Preliminary results: good performance
November 2024	Salmonella: serotyping and WGS analysis	Pure cultures	Interim serotyping results indicate 100% match with intended results – a good performance

Note 1: Performance grading taken directly from EURL PT reports.

The AR EURL organised the PT for antimicrobial sensitivity testing in Campylobacter, Salmonella and Escherichia coli. The individual reports from the EURL’s webtool indicates that the UK NRL attained 0% deviation for Campylobacter and Salmonella and only 0.5% deviation for E. coli (misinterpretation of cefepime result), generating satisfactory performance and under the 5% threshold for unsatisfactory performance.

In October 2024, the UK NRL received the detection of Salmonella PT in fabric swabs. The NRL achieved correct results for the 3 negative samples, 3 of 6 very low level and all 3 high level samples. For the low level samples, the NRL detected Salmonella in 2 of 4 of these samples and the NRL is awaiting further guidance from the EURL. The UKHSA NRL also received a panel of pure isolates through APHA for the serotyping and cluster analysis PT from the Salmonella EURL, as they registered on behalf of the UK. Interim serotyping results indicate that the UKHSA NRL matched 100% with the intended results of 20 Salmonella strains, achieving a good performance.

The Listeria EURL organised 2 PTs for challenge testing and cgMLST. The challenge testing PT aimed to evaluate laboratories’ ability to assess the growth potential of L. monocytogenes in vegan chocolate almond yoghurt and interpret whether the food was able to support the growth of L. monocytogenes. The UK NRL requested Campden BRI to participate in the PT, as experts in this field; many other NRLs in the EU also request third party providers to participate as this ensures challenge testing is of a required standard in their countries, which food businesses depend on to decide product shelf-life. Despite obtaining a deviation for reporting high pH results for day 14 data, the EURL accepted the corrective actions and the UK results were assessed as satisfactory. Ten pure cultures were sent for the cgMLST and serotyping PT and the UK NRL matched 100% with the intended results (serotype, clonal complex, clustering analysis) and achieved satisfactory performance.

In October 2024, a genomic PT was distributed by the National Food Institute (DTU) in Denmark for the pathogens E. coli, Staphylococcus aureus and Enterococcus faecium or faecalis. The UK NRL submitted detailed meta data, including methodology, quality parameters, and predicted antimicrobial phenotype. Preliminary analysis of the results looks encouraging, where most of the intended genes were reported by the NRL; a further report is awaited from the EURL to ascertain performance.

Referrals to detect staphylococcal enterotoxins in milk and cheese samples have remained very low in the UK, with on average one request for testing made every 3 years and therefore the need to maintain capability is unjustified for the UK NRL. Therefore, with agreement from the FSA, the NRL maintains a testing ability by sub-contracting the service to a designated OL in the EURL network, who regularly participates in the EURL proficiency testing.

Related to core functions: 1.a, 4.c, 4.d.

Organise teams or classroom-based workshops for UK OLs

In February 2025, the NRL organised a training workshop for its official laboratories on ‘Screening of Antimicrobial Resistant Bacteria in Food’. Hosted as a half-day online event, the aim was to cover introductory aspects of AMR testing and in total, over 26 delegates representing 10 OLs and APHA attended. Presentations were given by representatives from the UKHSA FWEMS and the APHA and covered why AMR testing in foods is important, the methodology used to screen for AMR bacteria, MIC (Minimum Inhibitory Concentration) and WGS testing on referred isolates and the process and results from recent projects undertaken by the FWEMS laboratories on AMR. To encourage interaction and discussions, a poll was conducted at different points during the event asking delegates about their knowledge of AMR before (20/24 delegates stated “just OK” or under) and after the training (20/21 delegates stated “good” or higher), whether laboratories perform AMR testing (10/24 delegates stated “no”), awareness of the requirements for AMR testing from the UK National Monitoring Plan (14/24 delegates stated “no”), and how easy it would be to implement the AMR method in the laboratories (8/22 stated “already doing AMR”, but another 8 either don’t get requests for AMR testing or would need the method, training and specific agar media to implement the method).

A feedback survey was circulated to all attendees, which included an option for a certificate of attendance. Analyses indicate a majority rating of ‘very good’ to ‘excellent’ for the content, discussion and material provided, where all respondents stated it met their objectives. There was one suggestion to add a practical session if the workshop was repeated in future.

Related to core functions: 2.a, 3.a, 4.e.

Analysis and publication of the 2023 OL capability and capacity audit

The UK NRL has published the 2023 OL capability and capacity audit on the gov.uk website. A summary of findings can be found earlier in this report in Core Function 1.

Related to core functions: 1.b, 2.d, 2.e, 4.g.

Core Function 5. Co-ordination within the UK of international initiatives

Support food aspect of the EU-wide AR monitoring (Decision EU 2020/1729)

Before leaving the EU, fresh meat at retail and animals at the slaughterhouse were sampled and tested in the UK by the APHA, in accordance with the above EU Decision. Since EU Exit, the UK continues to carry out this monitoring activity, to ensure consistency with the EU, but does not submit data to the EU. The NRL has maintained communications and awareness regarding this area of activity.

Related to Decision EU 2020/1729, 2 additional EU-wide baseline surveys have been developed: one on the prevalence of MRSA in fattening pigs, (EU) 2023/1017 which was applied in the EU from 1 January 2025 and another to estimate levels of AMR bacteria in aquaculture animals (Technical specifications for a EU‐wide baseline survey of antimicrobial resistance in bacteria from aquaculture animals). These surveys have been shared and discussed with APHA and CEFAS.

Additional information regarding APHA liaison and AMR work can be found above in ‘Core Function 1. Liaise with APHA regarding mutual NRL activities’.

Related to core functions: 1.b, 2.a, 5.a.

Participate in EURL activities relating to whole genome sequencing

In 2019, a European Commission mandate initiated a joint EURL activity to expand the molecular typing data collection to WGS data. This was formalised with the publication of Regulation (EU) 2025/179 which mandates all MSs to submit WGS data related to outbreak investigations to the EFSA One Health System of non-human isolates of Salmonella Enterica, Listeria monocytogenes and STEC, to allow for molecular surveillance and continuous monitoring. This will apply from the 23 August 2026, and although the UK is not part of the EU, there is interest in this activity.

Before the UK left the EU, the UK participated in a number of initiatives related to this activity. The UK is now restricted to only participate in PTs and particular training organised by the EURLs; these are complemented with regular checks of EURL and EU websites to maintain knowledge and compare UK activities with the EU. For example, the EURL working group for WGS arranged ‘Introduction to bioinformatics for genomic data mining’ training for the MSs and although the UK was not allowed to attend, the learning material can be found on the Zenodo website.

The UK NRL was invited by the AR EURL to the Oxford Nanopore sequencing training, which was previously described earlier in this report in ‘Core Function 2: Attend training workshops at international organisations’.

Related to core functions: 1.a, 2.e, 5.a.

Participate in training opportunities provided by international organisations

The NRL has attended several training events and these are described elsewhere in this report.

Related to core functions: 1.a, 2.e, 5.a.

Core Function 6. Communication of results and data use

The NRL has communicated to the FSA by means of monthly logs, quarterly meetings and newsletters and an annual report (this report), as well as any other correspondence as and when required. The 2023 OL capability audit report was shared with the FSA before publication to the gov.uk and any external meetings that the NRL has attended have been reported.

Related to core functions: 6.a to 6.m.

Core Function 7. Incident management

Representatives of the FW&E Microbiology Service participated in many health protection events and Incident Management Teams throughout the year, and key findings and lessons learnt were shared with the NRL, FSA and other colleagues as appropriate.

Relevant examples are described in the following reports:

• Prolonged multi‐country outbreak of Listeria monocytogenes ST173 linked to consumption of fish products
• Joint ECDC-EFSA rapid outbreak assessment: Prolonged multi-country outbreak of Salmonella Strathcona ST2559 linked to consumption of tomatoes in the EU/EEA and the UK
• Salmonella Braenderup in melons: How Honduras handled the unexpected
• Rapid outbreak assessment - Prolonged cross-border multi-serovar Salmonella outbreak linked to consumption of sprouted seeds

Discussion of specific areas

EU relations

Since leaving the EU on 31 January 2020 and due to the limited activities that the EURLs are now permitted to offer to the UK, the NRL regularly checks the EURL websites for new information which may be useful for the UK and produces reports based on presentations given at the EURL meetings.

The UK NRL has sought clarification and consent from FSA for specific activities where the UK NRL felt it was appropriate and mutually beneficial to respond and engage with the EURLs and EU. To strengthen this and ensure information is transparent and current, the NRL has liaised with FSA, Defra, and UKHSA EU Exit departments.

EU law continues to apply to Northern Ireland post EU Exit in respect of the Regulation (EU) 2017/625 and Northern Ireland is required to have NRLs based in the EU which have been designated by FSA to fulfil this obligation. The UK NRL continues to support the NI OL to try to reduce the burden of overlapping activities between UK and EU NRLs.

Despite these challenges, the NRL has continued to communicate with the EURLs and successfully participate in all of the relevant activities that the EURLs have offered, including attending meetings, participating in proficiency testing and receiving technical training.

Summary and forward look to proposed UKHSA NRL Activities, April 2025 to March 2026

Core Function 1. Secretariat services

1.a. Disseminate information or advice from international organisations to FSA, OLs and other UK laboratories in a timely and effective manner.
1.a. Produce and circulate quarterly newsletters to FSA, OLs and other UK laboratories.
1.a. Co-ordinate the OL User Day to update UK OLs and other relevant UK laboratories of the NRL core functions.
1.b. Prepare and carry out an audit regarding the OL’s accreditation status on the UKAS register.
1.b. Review content of the UK Food Examiner Register.
1.c. Continue liaison meetings with APHA for AMR, Campylobacter and Salmonella.
1.c. Liaise with CEFAS for E.coli and Salmonella in shellfish activities.
1.c. Liaise with Campden BRI to discuss and implement challenge testing activities
1.d. Produce and submit annual report to the FSA on NRL activities for 2024 to 2025.
1.d. Provide regular updates to the FSA on NRL activities by producing monthly reports.
1.e. Arrange quarterly meetings with FSA and FSS.
1.f. Maintain and update the NRL web content on the UKHSA website.

Core Function 2. Advice and representation within the UK and internationally

2.a. Provide impartial expert advice to FSA, OLs and other UK laboratories, upon request.
2.b. Represent the UK at relevant international meetings and working groups; consult FSA prior to meetings and submit an internal report after attendance of meetings.
2.c. Attend training workshops at international organisations, where relevant and after successful applications.
2.d. Liaise with FSA in matters UK’s concerning testing capabilities.
2.e. Keep abreast of methodology developments and advise FSA and OLs (for example AMR in Listeria spp from food literature review).
2.g. Participate in the BSI AW/9 microbiology committee.
2.g. Participate in Working Group to revise the ISO/TS 13136:2012 (PCR detection of STEC) and other working groups where appropriate.

Core Function 3. Research and development, including production of standard operating procedures, codes of practice and guidance documents

3.a.  Maintain UK food method list on NRL website.
3.b. Produce an SOP for detection of AMR in food.
3.c. Draft a manuscript for peer-review summarising multiple-year OL performance in the EFL PT scheme.

Core Function 4. Compliance assessment through audits and ring trials

4.a. Ensure consistency and quality of testing approached applied by UK OLs and support where necessary.
4.b. Liaise with FEPTU and monitor OL’s comparative testing performance and assist OLs in the implementation of corrective measures.
4.b. Evaluate OL’s performance using trend analysis and report appropriately to the FSA.
4.c. Co-ordinate the participation of OLs in international method validation studies and other initiatives and report to FSA.
4.d. Participate as UK-NRL in proficiency tests and method validation studies organised by the EURL (where available) and report to FSA.
4.e. Organise Teams or classroom-based workshops for UK OLs, dependent on the 2023 audit (1.b) and OL needs.
4.e. Organise a practical workshop for UK OLs, dependent on the 2023 audit (1.b) and OL needs.
4.g. Draft and circulation of the 2023 OL capability and capacity audit

Core Function 5. Co-ordination within the UK of international initiatives

5.a. Support the food aspect of the EU-wide AR monitoring (Decision (EU) 2020/1729), liaising with FSA, OLs, relevant Reference Laboratories and APHA.
5.b. Provide information regarding Whole Genome Sequencing when requested from the EURLs, and participate in any related workshops, proficiency testing, training and guidance documentation, where necessary.

Core Function 6. Communication of results and data use

Communicate with FSA on results and data use, when required.

Core Function 7. Incident management

Perform defined work when requested by FSA for incident management, with joint agreement and where appropriate.

Summary of NRL activities for April 2025 to March 2026

See the Summary of NRL activities for April 2025 to March 2026.

Annexe: Documents produced from NRL activities

Core Function 1. Secretariat services

EURL Websites:

• Listeria monocytogenes
• Coagulase-positive staphylococci
• STEC - ISS
• Campylobacter
• Salmonella
• Antimicrobial resistance

Dissemination of information from the EURLs related to core functions: 1.a, 1.c, 2.d, 2.e, 2.f:

• EURL-Salmonella Newsletter June 2024
• EURL-Salmonella Newsletter September 2024
• EURL-Salmonella Newsletter December 2024
• EURL-Salmonella Newsletter March 2025
• EURL-AR_Newsletter_2024_No18

Quarterly newsletters related to core functions; 1.a, 2.d, 2.e, 2.f:

• NRL newsletter Q1 2024-5_finalv2
• NRL newsletter Q2 2024-5
• NRL newsletter Q3 2024-5_final
• NRL newsletter Q4 2024-5_FINAL

Co-ordination of 2023 OL User Day related to core functions: 1.a, 1.b, 1.c, 2.a, 2.d, 2.e, 2.f, 6.l:

• User day 30sep2024 agenda_02.00

Provide regular updates to FSA related to core functions: 1.d, 6.a, 6.d, 6.k:

• FSA NRL Meeting 17Jun2024 minutes_final draft_KL_SN_AV_CWedits_v2
• FSA NRL Meeting 03Sept2024 minutes_Final Draft_KL_SNedits_CW
• FSA NRL Meeting 11Dec2024 minutes_Final Draft_KL_SN_AVedits CW
• FSA NRL Meeting 04Mar25_ Final minutes_NRL_SN_KLedits
• UK NRL Monthly Log for Apr24_final
• UK NRL Monthly Log for May24_Final
• UK NRL Monthly Log for Jun24_final
• UK NRL Monthly Log for July24_Final
• UK NRL Monthly Log for Aug24_Final
• UK NRL Monthly Log for Sept24_Final
• UK NRL Monthly Log for Oct24_Final
• UK NRL Monthly Log for Nov24_Final
• UK NRL Monthly Log for Dec24_Final
• UK NRL Monthly Log for Jan25_Final
• UK NRL Monthly Log for Feb25_Final
• UK NRL Monthly Log for Mar25_Final

Core Function 2. Advice and representation within the UK/EU

Representation at relevant EURL meetings and prepare meeting reports related to core functions: 1.a, 2.b:

• 2024-0026_EURL report of 2024 workshop
• Internal report_EURL Salmonella Workshop 2024_final plus EURL workshop report
• Internal report of EURL-AR meeting 2024_01.02_Final
• EURL Lm_2024 WS Report_UK NRL highlighted
• Internal report of EURL meeting_E.coli 2024 FINAL_further update June25_FINAL
• Summary of the 19th Campylobacter EURL Workshop 2024_final

Keep abreast of methodology developments related to core functions: 2.e, 2.f:

• Food Examiner (Senior Staff) Update June 2024
• STEC Testing Workshop Nov2024 Report v1.1
• FW&E Senior Staff Update March 2025 draft agenda (002)

Core Function 3. Production of standard operating procedures, codes of practice and guidance documents

Update food methods archive on NRL website related to core functions: 1.a, 1.e,  3.a, 4.a:

• UK national reference laboratory for food microbiology

Core Function 4. Compliance assessment through audits and ring trials

OL participation in the European Food Microbiology Legislation Proficiency Testing Scheme related to core functions: 4.a, 4.b, 4.c:

• EFL67 OL Summary_FSA_final
• EFL68 OL Summary_FSA_final
• EFL69 OL Summary_FSA_draft
• EFL70 OL Summary_FSA_final

Participate in EURL ring trials related to core functions: 1.a, 4.c, 4.d:

• SVAKOM225.1 - EURL PT report 36
• SVAKOM225.2.v2 - EURL-Campylobacter PT report 38
• EURL-AR_MRSA_PCR_PT_report_for_comments
• Report PT39_nonEU (1)
• Report NRL for Food Microbiology at UK health Security Agency_Signed
• 2024 Ecoli AST PT report for UK_52511924-04df-41de-93cb-81049464083a
• 2024 Campylobacter AST PT report for UK_52511924-04df-41de-93cb-81049464083a
• 2024 Salmonella AST PT report for UK_52511924-04df-41de-93cb-81049464083a
• Interim summary report EURL-Salmonella combined ILS-PT PPS-Food 2024
• LabX_individual_PT_report_Anses_LSAl_23_09_EURL_Lm_CT_2024
• Anses_LSAI_24_04_EURL_Lm_Typing_test_report_cgMLST
• Report_individual_PT41_20Jan2025
• DTU_Genomic_PT_2024_Guide_Draft_for_review
• Interim summary report EURL-Salmonella PT Serotyping 2024_Version2

Organise a practical workshop for UK OLs related to core functions: 2.a, 3.a, 4.e:

• Screening of AMR in food workshop agenda_final 01.03