ISO 11737-2:2019

Overview

ISO 11737-2:2019 - "Sterilization of health care products - Microbiological methods - Part 2" defines the criteria and practical guidance for tests of sterility used during the definition, validation and maintenance of a sterilization process. It applies to medical devices (health care products) that have been exposed to a reduced or fractional treatment with a sterilizing agent (verification dose), not to routine release sterility testing of fully processed product. The standard emphasizes method suitability, sample handling, and controlled test conditions to generate meaningful microbiological data for sterilization validation.

Key Topics and Requirements

• Scope and exclusions: Intended for tests of sterility performed after fractional exposure; not applicable to routine release testing, sterility tests for shelf‑life or package integrity, or culturing biological indicators (ISO 11138‑7 covers those).
• Sample selection and SIPs: Defines selection of product and the concept of a Sample Item Portion (SIP) - specified parts of the product to be tested. Requirements stress minimizing time between manufacture and exposure, and appropriate packaging of SIPs.
• Method suitability (bacteriostasis/fungistasis): Procedures to assess and demonstrate that the chosen microbiological method and culture conditions allow microbial recovery and growth, including dealing with inhibitory substances and providing rationale if full removal isn’t feasible.
• Testing conditions: Guidance on performing tests in a controlled environment, including immersion of samples in culture media where feasible, and procedures for identifying positive growth.
• Maintenance and reassessment: Periodic demonstration of ongoing method suitability to detect gradual changes over time; responsibilities and record controls for validation, routine control and documentation (Annex B).
• Practical guidance: Annex A offers technique-level guidance and considerations for interpreting sterility test results when defining or requalifying sterilization processes.

Applications and Users

ISO 11737-2:2019 is used by:

• Medical device manufacturers conducting sterilization process development and validation
• Contract laboratories performing microbiological testing for sterilization validation
• Quality assurance/quality control teams managing sterilization requalification and process maintenance
• Regulatory and compliance professionals demonstrating scientifically sound sterilization evidence

Practical applications include establishing radiation doses, confirming cycles for terminal sterilization, and evaluating product bioburden under reduced-exposure conditions.

Related Standards

• ISO 11135, ISO 11137 (radiation sterilization series), ISO 17665-1, ISO 14937, ISO 14160, ISO 20857 - standards for sterilization process development and validation
• ISO 11138-7 - guidance on culturing biological indicators
• ISO 13485 - quality management system considerations for medical devices

Keywords: ISO 11737-2:2019, tests of sterility, sterilization process validation, microbiological methods, sample item portion (SIP), method suitability, bioburden, medical device sterilization.