BS EN ISO 14161:2009 Sterilization of health care products. Biological indicators. Guidance for the selection, use and interpretation of results
BS EN ISO 14161 is the standard that provides guidance for the selection, use and interpretation of results from application of biological indicators when used in the development, validation and routine monitoring of sterilization processes.
BS EN ISO 14161 applies to biological indicators for which standards exist. See, for example, the ISO 11138 series.
The general information provided in BS EN ISO 14161 can have useful application for processes and biological indicators not currently addressed by existing standards, e.g., new and developing sterilization processes.
In BS EN ISO 14161, users will find guidance on selection of the correct biological indicator for their particular sterilization process and critical parameters as well as guidance on its appropriate use.
BS EN ISO 14161 is not intended to mandate the use of biological indicators in a process but, if they are used, it provides guidance for their proper selection and use in order to obviate misleading results.
BS EN ISO 14161 describes procedures of a general nature and that which do not constitute a comprehensive development, validation or monitoring programme with regard to the sterilization of health care products.
The user should select a biological indicator that is appropriate for the particular process to be used. There is a wide variety of sterilization processes in common use, and biological indicator manufacturers are not able to foresee all possible uses of their product. Manufacturers, therefore, label biological indicators according to their intended use. It is the responsibility of the users of biological indicators to select, use, recover and interpret the results as appropriate for the particular sterilization process used.
The certified performance of a biological indicator can be adversely affected by the conditions of storage and transport prior to its use, by the use of the biological indicator or by the sterilizer process parameters. In addition, the incubation procedure used after exposure to the process, including outgrowth temperature and culture medium type, supplier and specific lot, can affect measured resistance as a function of recovery and growth. For these reasons, the recommendations of the biological indicator manufacturer for storage and use should be followed. After exposure, biological indicators should be aseptically transferred (if applicable) and incubated as specified by the biological indicator manufacturer.
It should be noted that biological indicators are not intended to indicate that the products in the load being sterilized are sterile. Biological indicators are utilized to test the effectiveness of a given sterilization process and the equipment used, by assessing microbial lethality according to the concept of sterility assurance level. Suitably trained personnel should conduct these studies.
Contents of BS EN ISO 14161 include:
- Introduction
- Scope
- Normative references
- Terms and definitions
- Characteristics of biological indicators
- Test organism suspension for direct inoculation of products
- Inoculated carriers
- Self-contained biological indicators
- Other biological indicators
- Selection of supplier
- Documentation
- Biological indicators in process development
- Overkill approach
- Combined biological indicator and bioburden method
- Bioburden method
- Biological indicators in sterilization validation
- Placement and handling of biological indicators
- Sterilizer qualification
- Performance qualification
- Review and approval of validation
- Requalification
- Biological indicators in routine monitoring
- Placement and handling of biological indicators
- Process challenge device (PCD)
- Results
- Interpretation of results
- Application of biological indicator standards
- General assessment of biological indicator performance by the user
- Nominal population of test organism
- Resistance determination
- z value determination
- F(T, z) equivalent sterilization value determination
- Establishing spore-log-reduction (SLR)
- Sterility assurance level (SAL) calculation
- Test equipment
- Culture conditions
- Incubation temperature
- Incubation period
- Choice of growth medium
- Third-party requirements
- Minimum requirements for replicates and total number of biological indicators
- Test equipment
- Personnel training
- Storage and handling
- Disposal of biological indicators
- Microbiological inactivation kinetics and enumeration techniques
- Process challenge devices
- Formulae for fraction negative methods for D value calculations
- Examples of documentation for biological indicators prepared by the user
- Calculation of z value
- D value determination by survivor curve method
- Survival-kill response characteristics
- Bibliography
BS EN ISO 14161 does not consider those processes that rely solely on physical removal of microorganisms, e.g., filtration.
BS EN ISO 14161 is not intended to apply to combination processes using, for example, washer disinfectors or flushing and steaming of pipelines, nor is it intended to apply to liquid sterilization processes.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
BS EN ISO 14161:2009 replaces BS EN ISO 14161:2001 which has been withdrawn.