Overview
ISO 22118:2011 defines minimum performance characteristics for polymerase chain reaction (PCR) methods used to detect and quantify food‑borne pathogens in food, environmental samples and animal feeding stuffs. It sets requirements for molecular detection of nucleic acids (DNA/RNA), covering both qualitative and quantitative PCR workflows and the data needed to demonstrate method fitness for purpose.
Key topics and technical requirements
- Scope: Applies to PCR-based detection/quantification of food‑borne pathogens and isolates, including environmental and feed matrices.
- Selectivity (specificity / inclusivity / exclusivity):
- Empirical testing with relevant target variants; where available, test up to 50 target strains for inclusivity.
- For bacterial exclusivity testing, select a minimum of 30 non-target strains (≈90% bacteria, remainder fungi/viruses as relevant). For viruses, test at least 3 non-target virus strains.
- Sensitivity:
- Qualitative tests: method sensitivity typically 1–10 cells (bacteria/parasites) or 10–100 particles/genome equivalents (viruses) per assay in a defined food matrix.
- Quantitative tests: report upper and lower limits and linear range; evaluation should use matrices with realistic background flora.
- Sensitivity evaluation should include five different food categories.
- Limits:
- LOD (limit of detection) and LOQ (limit of quantification) must be determined and reported.
- Robustness:
- Assess effect of small deliberate variations (reagents, apparatus); interlaboratory studies can determine interlaboratory ruggedness.
- Analytical controls:
- Positive, negative, internal/external amplification controls and their interpretation must be specified (see ISO 22174 for control detail).
- Trueness & precision:
- Provide empirical data on accuracy and reproducibility; in‑house validation requires at least two operators and duplicate runs starting from nucleic acid extraction.
- Instruments:
- Specify validated instruments; alternate equipment may be used only after experimental verification.
Applications and who uses it
ISO 22118 is intended for:
- PCR assay and kit developers documenting performance claims
- Food and feed microbiology laboratories validating in‑house methods
- Third‑party validation and accreditation bodies assessing method suitability
- Regulatory agencies and quality control teams comparing molecular and conventional methods
- Research labs conducting method development or interlaboratory studies
Practical uses include validation of commercial PCR assays, defining LOD/LOQ for quantitative tests, demonstrating selectivity in complex food matrices, and supporting accreditation or regulatory acceptance.
Related standards
- ISO 16140 (validation of alternative methods)
- ISO 22174 (PCR - general requirements and definitions)
- ISO 22119 (real‑time PCR - general requirements)
- ISO 20836 / 20837 / 20838 (PCR method components such as thermal cyclers, sample prep, amplification/detection)
Keywords: ISO 22118:2011, PCR, food-borne pathogens, performance characteristics, LOD, LOQ, validation, selectivity, sensitivity, robustness, food microbiology.
Open preview (PDF)Microbiology of food and animal feeding stuffs — Polymerase chain reaction (PCR) for the detection and quantification of food-borne pathogens — Performance characteristics