The chemical indicators or indicator systems described in this part of ISO 11140 The six indicator types described in the main body of this part of ISO 11140 are categorized according to their performance requirements. The chemical indicators within each of these categorizations are further subdivided by the sterilization process for which they are designed to be used. These categorizations have no hierarchical significance. Attainment of the chemical indicator’s end point should not be regarded as an indication of attainment of an acceptable sterility assurance level, but rather one of many factors which should be taken into consideration when judging the acceptability of a sterilization process.
What are the 6 types chemical indicators for steam sterilization?
Sterilization practices are vitally important for the successful treatment of patients and clients, as it is essential that all potentially hazardous organisms are destroyed. Chemical indicators are one useful tool for assessing the adequacy of sterilization procedures, allowing practitioners to reliably determine whether a load of materials has been adequately treated. In this article, chemical indicators for sterilization will be discussed according to the six categories outlined in ISO 11140, as well as the different sterilization processes for which they are designed.
Class 1 chemical indicator are designed to monitor the thermal sterilization process and are intended to provide visible indicators of the sterilization process. They measure such physical parameters as temperature, time and pressure, providing a visual sign of whether a load has been appropriately treated.
Class 2 indicators are intended to monitor the sterilization process itself and are primarily used in steam sterilization processes. These indicators contain two components: a heat-sensitive indicator which changes color when exposed to the steam and a moisture-sensitive indicator which changes color when exposed to moisture.
Class 3 indicators are intended to monitor the chemical sterilization process, and they are primarily used with ethylene oxide and hydrogen peroxide sterilization processes. These indicators change color when exposed to their respective chemical reagents, and can be a useful tool for ensuring that a load has been adequately treated.
Class 4 indicators are designed to monitor the chemical and physical parameters of the sterilization process, providing an evaluation of the chemical, biological, or radiological integrity of a given load. They can be used for steam, ethylene oxide and hydrogen peroxide sterilization processes and should be employed whenever a precise dosimetry of these chemicals or radiation is essential.
Class 5 indicators are designed to monitor the effectiveness of the sterilization process and can be used to detect parametric failures of various sterilization processes. They change color when exposed to a given parameter of their respective sterilization process, even in the presence of a competing chemical or process parameter. These indicators are especially useful for double-check monitoring of the sterilization process.
Finally, Class 6 indicators are bio-indicators which are used to assess the actual microbial load of a given load after the completion of the sterilization process. These are typically used to measure the actual presence of viable organisms in the load after treatment and are essential for determining the actual effectiveness of the sterilization process.
In conclusion, chemical indicators for sterilization can be divided into six main categories, each having its own use and application in the sterilization process. The responsible practitioner should become familiar with the various classes of indicators that are available and understand their intended purpose in assessing the sterile status of materials and equipment.Additional Resources
- FDA Guidance on Sterilization.
- ISO Standards for Sterilization: ISO 11607 and ISO 11140.
- Ethylene Oxide Sterilization: Principles and Practices:
