ISO/TC 198/WG 4 - Biological indicators

1.1 This document specifies the requirements for a test method to be utilized to establish or confirm a reduced incubation time (RIT) that is shorter than the 7-day reference incubation time specified in 7.3.2 of ISO 11138-1:2017 for biological indicators used to monitor moist heat sterilization processes or ethylene oxide (EO) sterilization processes. NOTE: For biological indicators used for EO sterilization, the stated RIT is applicable to 100 % EO processes or processes that use EO blends, regardless of the product load. 1.2 This document is applicable to manufacturers of biological indicators (BIs) and to end users of BIs who intend to, if required by their quality system, establish, validate or confirm a RIT. 1.3 This document does not apply to biological indicators used to monitor dry heat, low temperature steam formaldehyde (LTSF) or vaporized hydrogen peroxide (VH2O2) sterilization processes. NOTE The method described in this document to establish a RIT for biological indicators used to monitor moist heat or EO sterilization processes has been used extensively for many years. However, there is limited experience in use of this method to establish a RIT for biological indicators used to monitor dry heat, low temperature steam formaldehyde or vaporized hydrogen peroxide sterilization processes. This document, therefore, does not include these sterilization processes.

This document 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. It does not consider those processes that rely solely on physical removal of microorganisms, e.g. filtration. It is not applicable to combination processes using, for example, washer-disinfectors or flushing and steaming of pipelines. It does not specify requirements for the selection and use of biological indicators intended to monitor vaporised hydrogen peroxide processes for isolator and room biodecontamination processes at atmospheric pressure. It is not applicable to liquid immersion sterilization processes.

This document specifies the requirements for test equipment to be used to: — test biological indicators for steam, ethylene oxide gas and dry heat sterilization processes for conformity to the requirements given in ISO 11138 series; — test chemical indicators for steam, ethylene oxide gas, dry heat and vaporized hydrogen peroxide sterilization processes for conformity to the requirements given in ISO 11140‑1:2014. This document also provides informative methods useful in characterizing the performance of biological and chemical indicators for intended use and for routine quality control testing. This document does not specify requirements for test equipment for processes specifically for testing chemical and biological indicators intended to monitor isolator and room biodecontamination processes at atmospheric pressure. ISO 11138‑2:2017, ISO 11138‑3:2017, ISO 11138‑4:2017 and ISO 11140‑1:2014 require the use of resistometers specified in this document, and these resistometers are used in conjunction with the test methods specified in the appropriate parts of ISO 11138 series and ISO 11140 series. Resistometers for low temperature steam and formaldehyde indicators are not included in this document. Test methods using laboratory apparatus for low temperature steam and formaldehyde are included in ISO 11138‑5:2017. Test equipment for testing Type 2 (e.g. Bowie Dick) chemical indicators are specified in ISO 11140‑3:2007, ISO 11140‑4:2007, and ISO 11140‑5:2007.

 ISO 11138-1:2017 specifies general requirements for production, labelling, test methods and performance characteristics of biological indicators, including inoculated carriers and suspensions, and their components, to be used in the validation and routine monitoring of sterilization processes. ISO 11138-1:2017 specifies basic and common requirements that are applicable to all parts of ISO 11138. Requirements for biological indicators for particular specified processes are provided in the relevant parts of ISO 11138. If no specific subsequent part is provided, this document applies. NOTE National or regional regulations can apply. ISO 11138-1:2017 does not apply to microbiological test systems for processes that rely on physical removal of microorganisms, e.g. filtration processes or processes that combine physical and/or mechanical removal with microbiological inactivation, such as use of washer disinfectors or flushing and steaming of pipelines. This document, however, can contain elements relevant to such microbiological test systems.

ISO 11138-3:2017 specifies requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilization processes employing moist heat as the sterilizing agent. NOTE 1 Requirements for validation and control of moist heat sterilization processes are provided by the ISO 17665 series. NOTE 2 National or regional regulations can provide requirements for work place safety.

ISO 11138-2:2017 specifies requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilizers and sterilization processes employing ethylene oxide gas as the sterilizing agent, either as pure ethylene oxide gas or mixtures of this gas with diluent gases, at sterilizing temperatures within the range of 29 °C to 65 °C. NOTE 1 Requirements for validation and control of ethylene oxide sterilization processes are provided by ISO 11135 and ISO 14937. NOTE 2 National or regional regulations can provide requirements for work place safety.

ISO 11138-4:2017 specifies requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilization processes employing dry heat as the sterilizing agent at sterilizing temperatures within the range of 120 °C to 180 °C. NOTE 1 Requirements for validation and control of dry heat sterilization processes are provided by ISO 20857. NOTE 2 Requirements for work place safety can be provided by national or regional regulations.

ISO 11138-5:2017 specifies requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilization processes employing low-temperature steam and formaldehyde as the sterilizing agent. NOTE 1 Requirements for validation and control of low-temperature steam and formaldehyde sterilization processes are provided by ISO 14937. NOTE 2 Requirements for work place safety can be provided by national or regional regulations.

ISO 14161:2009 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. ISO 14161:2009 applies to biological indicators for which International Standards exist.

ISO 11138-2:2006 provides specific requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilizers and sterilization processes employing ethylene oxide gas as the sterilizing agent, either as pure ethylene oxide gas or mixtures of this gas with diluent gases, at sterilizing temperatures within the range of 29 °C to 65 °C.

ISO 11138-5:2006 provides specific requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilization processes employing low-temperature steam and formaldehyde as the sterilizing agent.

ISO 11138-4:2006 provides specific requirements for test organisms, suspensions, inoculated carriers, biological indicators, and test methods intended for use in assessing the performance of sterilization processes employing dry heat as the sterilizing agent at sterilizing temperatures within the range of 120 °C to 180 °C.

ISO 11138-3:2006 provides specific requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilization processes employing moist heat as the sterilizing agent. Moist heat as the sterilizing agent is defined in ISO 11138-3:2006 as dry saturated steam. While air-steam mixtures may be used in moist heat sterilization processes, the methods and performance requirements of this part of ISO 11138 might not be applicable for biological indicators used in such processes.

ISO 11138-1:2006 provides general requirements for production, labelling, test methods and performance characteristics of biological indicators, including inoculated carriers and suspensions, and their components, to be used in the validation and routine monitoring of sterilization processes.ISO 11138-1:2006 specifies basic and common requirements that are applicable to all subsequent parts of ISO 11138. Requirements for biological indicators for particular specified processes are provided in the subsequent parts of ISO 11138. If no specific subsequent part is provided, this part applies.

Gives specific requirements for test organisms and biological indicators intended for use in assessing the performance of sterilizers employing moist heat as the sterilant.

Provides specific requirements for test organisms and biological indicators intended for use in assessing the performance of sterilizers employing pure ethylene oxide gas or admixtures of the gas with diluent gases at sterilizing temperatures within the range of 20 °C to 65 °C.

Specifies general production, labelling and performance requirements for the manufacture of biological indicators and suspensions intended for use in the validation and monitoring of sterilization cycles. Does not contain requirements for product directly inoculated with test organisms, or recovery procedures for such inoculated product.