External quality assessment for identification, antimicrobial susceptibility testing and molecular typing of Neisseria meningitidis, 2026

Invasive meningococcal disease remains a major public health concern because of its rapid progression, severity, outbreak potential and relevance for vaccine-preventable disease surveillance. High-quality laboratory capacity is essential to ensure timely detection, reliable serogroup determination, antimicrobial susceptibility testing and genomic characterisation of Neisseria meningitidis, including for culture-negative cases. 

This external quality assessment was organised within the IBDLabNet framework to assess current European Union/European Economic Area (EU/EEA) laboratory capacity for the diagnosis and characterisation of N. meningitidis in both non-culture and culture-based settings, and to identify areas requiring further harmonisation or technical support. The exercise included a shared non-culture panel and an optional meningococcal culture panel. Samples were shipped in December 2025, the online response form was made available in January 2026, and the submission deadline was 15 April 2026. 

A total of 34 EU/EEA laboratories from 24 countries were included in the EU/EEA analysis. All 34 EU/EEA laboratories received the non-culture panel, and 32/34 submitted at least one non-culture sample result in REDCap. The meningococcal culture panel was requested by 26 laboratories overall, with 25 EU/EEA laboratories providing analysable isolate-level results. 

Overall, the exercise showed strong performance for culture-based meningococcal identification and serogroup determination. All laboratories with analysable results correctly identified both cultured isolates as N. meningitidis, and serogroup assignment was highly concordant. AST uptake was high among laboratories providing culture panel results. Comparative MIC analysis showed higher agreement for cefotaxime and ciprofloxacin, while greater dispersion was observed for penicillin G, amoxicillin, rifampicin and ceftriaxone where reported. Complementary European Committee on Antimicrobial Susceptibility Testing (EUCAST)-based analysis showed that ciprofloxacin resistance in N1 sample was recognised by 19/21 laboratories reporting a numeric ciprofloxacin MIC, while cefinase/beta-lactamase positivity in N2 sample was reported by 10/25 isolate responders and by 10/12 laboratories providing an interpretable Yes/No result. 

Whole-genome sequencing (WGS) was reported by approximately two-thirds of laboratories with analysable meningococcal culture-panel results. Among WGS-positive submissions, reporting completeness was high for core surveillance outputs such as sequence type, clonal complex and major antigenic markers. More specialised outputs, including some resistance-associated loci and extended nomenclature fields, were less consistently reported. 

By contrast, performance on non-culture meningococcal samples was more heterogeneous. Correct pathogen detection was lower than for cultured isolates, and the main error pattern was false-negative reporting rather than misidentification as another pathogen. Among laboratories that reported a serogroup result, the serogroup was usually assigned correctly (approximately 72–74% of typed submissions). However overall sample-level success remained lower because many laboratories did not report a serogroup, in addition to those that failed to detect the pathogen. These findings indicate that non-culture molecular workflows remain the main area of variability across the participating network. 

The EQA confirms that EU/EEA laboratories participating in IBDLabNet have strong capacity for isolate-based meningococcal confirmation and characterisation, high AST uptake and substantial WGS-supported surveillance capacity. Priority areas for improvement include strengthening non-culture molecular detection, improving completeness of serogroup assignment from clinical material, maintaining standardised MIC reporting, improving recognition and reporting of resistance-relevant phenotypes, and further harmonising WGS-derived outputs. 

The design of the exercise was appropriate to document current practice and identify surveillance-relevant gaps across the network. Interpretation should take into account the limited number of meningococcal samples, the absence of a negative non-culture sample, optional participation in the culture component, the use of participant modal MICs for comparative AST analysis, and the descriptive nature of the WGS assessment. 

Recommended next steps include continued regular EQA rounds, targeted feedback to participating laboratories, improved collection of methodological information for non-culture workflows, focused training on molecular detection and serogrouping from non-culture material, continued support for standardised AST reporting, and progressive harmonisation of WGS-based reporting. These actions would further strengthen the quality and comparability of IMD surveillance data across the EU/EEA.