Overview
EN ISO 16140-4:2020/A2:2025 is an amendment to EN ISO 16140-4:2020 issued by CEN in 2025. This amendment adds Annex I, which provides a protocol for single-laboratory validation of identification methods of microorganisms. It aligns single-lab practice with the performance characteristics described in ISO 16140-7:2024 and references standardized concepts in ISO 17468:2023.
The annex is specifically applicable to laboratories that need to demonstrate the performance of identification methods (e.g., multiplex PCR, DNA sequencing, mass spectrometry) within a single facility. Results from a single-laboratory validation are valid only for the laboratory that conducted the study.
Key Topics
- Scope and purpose: Annex I clarifies when single-laboratory validation of identification methods is appropriate and how to document such studies.
- Performance basis: Single-lab studies shall be performed in accordance with the performance characteristics study in ISO 16140-7:2024, Clause 6.
- Strain selection and coverage:
- Test strains should cover the biodiversity encountered in the testing laboratory and a rationale for selection must be provided.
- Recommended minimums: at least 25% of genera and 10% of species within the method scope, where feasible.
- Absolute limits: minimum 250 strains and maximum 1 000 strains for broader scopes; for restricted database content (e.g., 25 genera, 200 species), test all listed genera and species.
- For restricted-scope methods (e.g., multiplex assays), include relevant negative-control strains that should not be identified by the method.
- Documentation: A validation study report must justify strain choices, describe methods tested, and present performance data.
- Limitations: Single-laboratory validation demonstrates method performance only in the validating laboratory; it does not replace interlaboratory studies when those are required.
Applications
This amendment and Annex I are practical for food microbiology and feed-testing laboratories that:
- Validate in-house identification workflows (e.g., MALDI-TOF, PCR panels, targeted sequencing) under a controlled, single-lab protocol.
- Need traceable, documented evidence of method performance for accreditation, quality control, or regulatory interaction.
- Work with restricted-scope identification databases and require a clear strategy for negative controls and strain coverage.
Practical steps for labs:
- Review ISO 16140-7:2024 performance characteristics and align your test plan to Clause 6.
- Define scope, database content and expected outcomes; select strains covering encountered biodiversity.
- Execute identification runs, collect performance metrics, and compile a validation report with rationale and conclusions.
Related Standards
- ISO 16140-7:2024 - Protocol for validation of identification methods of microorganisms (performance characteristics).
- ISO 17468:2023 - Technical guidance on standardized reference methods.
- ISO 16140-6 - Validation for alternative confirmation methods (related context).
- ISO 23418 - Notes on whole-genome sequencing (WGS) as a future reference method.
This amendment strengthens the ISO 16140 series by providing a clear, repeatable approach for single-lab validation of microorganism identification methods, supporting reliable method validation, scope control, and documented performance in food-chain microbiology laboratories.
