Sterility culture Indications :
A biological indicator is a specific preparation of a microorganism
which provides stable resistance to a process of sterilization. For example, a preparation of the bacillus
stearothermophilus is used regularly to test steamed autoclaves The preparation of the biological indicator must be well documented.
One biological indicator includes bacterial spores added to filter paper strips and, packaged to maintain their viability. The package must be designed in such a way as to allow penetration by the sterilizing agent, after which the strip is immersed in a culture media. The culture is allowed to grow for a few days.
The sterility culture test using biological indicators must be used at least once a week to validate a sterilization
process. The selection of the biological indicator is based on the knowledge of the indicator’s résistance to the sterilization process. Normal Range :
No growth in test strips
Interpretation : Normal
No growth of micro organism is seen on the test strips. This validates the credibility of the sterilization process employed
Growth of micro organisms seen, indicating a faulty sterilization process. Sample :
Three strips (one control and two test strips)
Test Method :
Indicator strips impegrenated with spores of Bacillus stearothermophilus are used with steam autoclaves