ISO 22117:2019

Overview

ISO 22117:2019 - "Microbiology of the food chain - Specific requirements and guidance for proficiency testing by interlaboratory comparison" provides targeted requirements and guidance for organizing proficiency testing (PT) schemes for microbiological examinations across the food chain. It applies to testing of foods and beverages, feedingstuffs, environmental samples from production and handling, primary production stages, and water when used in food production or legally regarded as food.

This standard focuses on the technical organization and statistical treatment of PT schemes specific to microbiology and is intended to be used alongside ISO/IEC 17043 and ISO 13528.

Key topics and technical requirements

• Scheme design and objectives
  • Define purpose, participant requirements, test matrices and statistical design to meet method and commodity needs.
• Sample design and content
  • Guidance on selection of matrices, target organisms, background flora and potential interferences.
• Sources, characterization and traceability
  • Use of reference strains and traceable organisms appropriate to food-sector testing.
• Sample verification
  • Homogeneity testing (for quantitative enumeration and qualitative detection methods) and stability testing for storage and transport.
• Sample handling and participant instructions
  • Requirements for shipping, handling, safety data sheets and clear test instructions.
• Performance evaluation
  • Statistical treatment for quantitative (enumeration) and qualitative (detection) results, determination of assigned values, uncertainty of assigned values, use of z‑scores and alternative performance metrics, plus long‑term performance assessment.
• Annexes and practical guidance
  • Practical annexes include PT scheme plan examples, fungal spore preparation, homogeneity testing methods and safety data sheet templates.

Applications and who uses it

ISO 22117:2019 is used by:

• Proficiency testing providers designing microbiology PT/EQA schemes.
• Food microbiology laboratories participating in PT to assess trueness (bias), precision and staff competence.
• Accreditation bodies and regulatory authorities evaluating laboratory competence and supporting conformity assessment.
• Quality managers in food producers, feed manufacturers and environmental testing labs for benchmarking and continuous improvement.
• Reference laboratories and method validation teams needing standardized statistical approaches for interlaboratory comparisons.

Practical uses include laboratory accreditation support, estimation of measurement uncertainty (enumeration), determination of detection limits (qualitative), method validation insights, and ongoing monitoring of laboratory performance.

Related standards

• ISO/IEC 17043 - General requirements for proficiency testing
• ISO 13528:2015 - Statistical methods for proficiency testing by interlaboratory comparison
• ISO 5725, ISO 3534 - Relevant statistical vocabularies and accuracy principles

Keywords: ISO 22117:2019, proficiency testing, interlaboratory comparison, microbiology of the food chain, PT schemes, sample homogeneity, stability testing, z‑scores, ISO/IEC 17043, ISO 13528.