Final answer:
The best method for verifying proper sterilization function is using biological indicator spore tests with Geobacillus stearothermophilus endospores. This method checks both temperature and exposure time, making it the most comprehensive. The use-dilution test measures disinfectant effectiveness, not sterilization.
Step-by-step explanation:
The most reliable method for determining whether there is proper sterilization function of a sterilizer, such as an autoclave, is the use of biological indicator spore tests. These tests involve using the endospores of Geobacillus stearothermophilus, which are known for their high heat resistance and are the gold standard for this purpose. The biological indicators are autoclaved along with the materials to be sterilized, and afterward, the endospores are incubated to ensure no viable endospores remain.
If the spores are killed effectively, this indicates that the autoclave is functioning properly. Other types of indicators include heat-sensitive autoclave tape and Diack tubes, but biological spore indicators are considered the most comprehensive as they account for both the appropriate temperature and the necessary duration of exposure.
In clinical settings, the use-dilution test is commonly used to assess the correct application of disinfectant solutions on inanimate surfaces. However, this test does not measure sterilization but rather disinfection effectiveness. Autoclaves, which use moist-heat sterilization, are seen as the most effective method for achieving sterilization because this method penetrates cells more effectively than dry heat.