Yingtai: The Definition, Function, Composition, Application, and Usage of Sterilization Indicators
Definition and Function of Sterilization Indicators
A sterilization indicator is a tool used to verify the performance of sterilization equipment, validate sterilization procedures, and monitor the effectiveness of sterilization in production processes. It typically contains microorganisms with a defined resistance to specific sterilization treatments. These microorganisms are placed in an inner packaging for use. The primary function of the sterilization indicator is to assess whether the sterilization process has achieved the desired effect by observing the survival or death of the microorganisms inside.
Composition and Characteristics of Sterilization Indicators
Sterilization indicators generally consist of the following components:
- Microbial Disc: Contains a certain number of specific microorganisms, such as Geobacillus stearothermophilus spores (ATCC 7953).
- Culture Medium: Used for microbial growth, typically sealed inside a glass tube.
- Plastic Outer Shell: Protects the microbial disc and culture medium, making it easier to handle and use.
Key characteristics of sterilization indicators include:
- D-value: The time required under specific sterilization conditions to reduce the microbial population by 90%. The larger the D-value, the more resistant the microorganism is to the sterilization process.
- Survival Time and Sterilization Time: The shortest time the microorganisms can survive under specific sterilization conditions and the shortest time required to completely kill them.
Application Scenarios for Sterilization Indicators
Sterilization indicators are widely used in industries such as healthcare, pharmaceuticals, and food processing to verify and monitor the effectiveness of various sterilization methods, such as pressure steam sterilization, ethylene oxide sterilization, and low-temperature plasma sterilization. Specific application scenarios include:
- Medical Equipment Sterilization Verification: Ensures that medical devices are effectively sterilized before use, preventing cross-contamination.
- Pharmaceutical Production Sterilization Monitoring: Ensures that pharmaceutical products are not contaminated by microorganisms during production, guaranteeing their safety and efficacy.
- Food Processing Sterilization Verification: Ensures that food is free from microbial contamination during processing, extending its shelf life.
Usage Method of Sterilization Indicators
The typical steps for using a sterilization indicator are as follows:
1. Record Information: Record necessary information on the label of the indicator, such as sterilization treatment date and location.
2. Place the Indicator: Position the indicator in a location within the sterilizer where it is least likely to be fully sterilized, providing a better reflection of the sterilization effect.
3. Sterilization Treatment: Sterilize the indicator, usually through methods like pressure steam, ethylene oxide, or low-temperature plasma sterilization.
4. Cooling and Cultivation: After sterilization, remove the indicator, cool it to room temperature, and place it in the culture medium for incubation.
5. Result Determination: Observe the color change of the culture medium to assess the sterilization effect. If the medium changes color, it indicates incomplete sterilization; if the color remains unchanged, sterilization is considered complete.
Result Determination of Sterilization Indicators
The result of a sterilization indicator is usually determined based on the color change of the culture medium. The specific criteria are as follows:
- Color Change: If sterilization is incomplete, surviving microorganisms will reproduce and metabolize into acids, causing the culture medium to change from purple-red to yellow. If sterilization is complete, all microorganisms are killed, and the culture medium remains purple-red.
- Control Tube: To ensure the validity of the result, an unused indicator from the same batch is usually used as a control tube. The culture medium in the control tube should change from purple-red to yellow, indicating that microorganisms can grow normally.
Precautions for Using Sterilization Indicators
When using sterilization indicators, the following points should be noted:
- Pre-Use Inspection: Ensure the integrity of the indicator and use it within its validity period.
- Avoid Proximity to Sterilizers and Chemical Disinfectants: This may affect the performance of the indicator.
- Waste Disposal: Indicators that have been determined to be incomplete in sterilization or have exceeded their validity period should be discarded after sterilization.
- Sealed Cultivation: To prevent evaporation of the culture medium during high-temperature incubation, the indicator should be sealed.
Sterilization indicators are important tools for verifying and monitoring the effectiveness of sterilization processes. They are widely used in healthcare, pharmaceuticals, food processing, and other industries to prevent microbial contamination and ensure the safety and efficacy of products.
