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Evaluation of high-temperature and short-time sterilization of injection ampules by microwave heating
1Quality Control Department, Misato Plant, Eisai Company Limited, Saitama, Japan.
Abstract:
The high-temperature and short-time sterilization by microwave heating with a continuous microwave sterilizer (MWS) was evaluated. The evaluation were performed with respect to: [1] lethal effect against microorganisms corresponding to F-value, and [2] reliability of MWS sterilization process. Bacillus stearothermophilus ATCC 7953 spores were used as the biological indicator and the heat-resistance of spores was evaluated with conventional heating method (121-129 degrees C). In MWS sterilization (125-135 degrees C), the actual lethal effect against B. stearothermophilus spores was almost in agreement with the F-value and the survival curve against the F-value was quite consistent with that for the autoclave. These results suggest that the actual lethal effect could be estimated by the F-value with heat-resistance parameters of spores from lower than actual temperatures and that there was no nonthermal effect of the microwave on B. stearothermophilus spores. The reliability of sterilization with the MWS was confirmed using more than 25,000 test ampules containing biological indicators. All biological indicators were killed, thus the present study shows that the MWS was completely reliable for all ampules.
Insights
Microwave sterilization (MWS) effectively kills microorganisms like Bacillus stearothermophilus spores, matching traditional autoclave sterilization. This study confirms MWS is a reliable high-temperature, short-time sterilization method.
Area of Science:
- Microbiology
- Sterilization Technology
- Food Safety
Background:
- High-temperature, short-time (HTST) sterilization is crucial for microbial inactivation.
- Microwave heating offers a rapid heating mechanism for sterilization processes.
- Evaluating the efficacy and reliability of novel sterilization methods is essential for public health.
Purpose of the Study:
- To assess the lethal effect of microwave sterilization (MWS) on microorganisms.
- To determine the reliability of the MWS process for sterilization.
- To compare MWS efficacy with conventional autoclaving methods.
Main Methods:
- Utilized Bacillus stearothermophilus ATCC 7953 spores as biological indicators.
- Evaluated heat resistance using conventional heating (121-129°C) and MWS (125-135°C).
- Assessed microbial inactivation using F-value calculations and survival curves.
Main Results:
- The lethal effect of MWS closely aligned with F-value predictions, similar to autoclave performance.
- Survival curves against F-value were consistent with conventional autoclaving.
- No nonthermal microwave effects were observed on Bacillus stearothermophilus spores.
Conclusions:
- F-value effectively estimates the lethal effect of MWS, even with spore heat resistance parameters from lower temperatures.
- The MWS process demonstrated complete reliability, with all 25,000+ biological indicators inactivated.
- MWS is a validated and reliable method for high-temperature, short-time sterilization.