Sterile pharmaceutical products are best administered to patients in sterile form, devoid of microbial lives. If they are administered with contaminations (i.e. containing any microorganisms or its products). It can lead to secondary infection, thus worsening the patients’ health and consequentially death.
Examples of these sterile products include parenteral preparations, injectable, and injection fluids among others. The autoclave is important equipment that plays a role in helping pharmacists and laboratory scientists to attain sterility in pharmaceutical products during the production process.
The autoclave is laboratory equipment that sterilizes loads via hot steam. It is used for sterilizing laboratory tools such as glassware, forceps, water for preparing formulations as well as heat-stable components of pharmaceutical formulations. The autoclave is one of the equipment highly relied upon by pharmaceutics during formulations. If there is sterilization failure during autoclaving, it can lead to high contaminations of pharmaceuticals and thus therapeutic failure, secondary infection, sanction by the government against such industry, and consequentially withdrawer of production license from implicated companies.
Efficiency testing is carried out for newly manufactured autoclaves during the quality control process before they are released to the market for pharmaceutical companies and laboratories which use it for sterilization.
CULTURE MEDIA FOR STERILITY TESTING (DIRECT METHOD)
In the direct method of sterility testing, both bacterial and fungi species and their spores are often tested for their ability to persist and proliferate after subjecting them to moist heat at 1210C for 15 minutes.
Culture media commonly used for bacteriological testing include:
- Thioglycollate medium
- Soya- bean Casein Digest medium
Culture media commonly used for fungi testing include:
- Potato Dextrose Agar
- Sabouraud Dextrose Agar
The organisms commonly in direct method of sterility test
|Aerobic bacteria||Anaerobic bacteria||Fungi|
|Staphylococcus aureus||Clostridium sporogenes||Candida albicans|
|Bacillus subtilis||Bacillus stearothermophilus||Aspergillus brasiliensis|
DIRECT METHOD OF STERILITY
In this method, the autoclave is loaded with filter papers, plasters or carriers that have been inoculated with microorganisms. It is thereafter subjected to steam under pressure at 1210C for 15 minutes. After which it is the load is removed and plated on appropriate culture media for 14 days for the observation of growth. This test is often carried out in three phases
- Direct sterility test using aerobic bacteria
- Direct sterility test using anaerobic bacteria
- Direct sterility test using fungi
DIRECT STERILITY TEST USING AEROBIC BACTERIA
The aerobic test bacteria often used include S. aureus, B. subtilis, and P. aeruginosa. In this type of sterility testing, the test bacteria are inoculated into either a filter paper or a carrier and loaded into the autoclave for sterilization at 1210C 15 minutes. After the sterilization, the filter paper or carrier is placed aseptically on bacterial culture media (Thioglycollate medium and Soya- bean Casein Digest medium) and incubated for 14 days at 370C with frequent observation for growth.
This is done by incubating a filter paper or a carrier that has been inoculated with the test aerobic organisms mentioned above in both Thioglycollate or Soya-bean Casein Digest media and observation for growth intermittently within 14 days
The negative control is a done by incubated a sterile filter paper or carrier in the same culture media for 14 days followed by frequent observation for growth.
DIRECT STERILITY TEST USING ANAEROBIC BACTERIA
For this type of test, spores of anaerobic bacteria such as Clostridium sporogenes and Bacillus stearothermophilus are inoculated on filter paper or carrier, then loaded into the autoclave and subjected to a temperature of 1210C for 15 minutes. After which either the filter paper or the carrier will be incubated in Thioglycollate medium and Soya- bean Casein Digest media in candle jar (or anaerobic jar) for 14 days with frequent observation of the media for growth.
This is done by incubating a filter paper or a carrier that has been inoculated with the spores of test aerobic organisms mentioned above in both Thioglycollate and Soya-bean Casein Digest media in candle jar and observation for growth in 14 days
For the negative control, sterile filter paper or a carrier will be placed culture media for 14 days likewise. Alternatively, the negative control can be a culture media with nothing inoculated or placed on it.
DIRECT STERILITY TEST USING FUNGI
Yeast (Candida albicans) and a mold, Aspergillus brasiliensis is often used for this test. The yeast is inoculated on a filter paper or carrier while the spores from Aspergillus brasiliensis. Then loaded in an autoclave and supposedly sterilized at 1210C. The filter paper or carrier is then removed and placed on either Potato Dextrose Agar or Sabouraud Dextrose Agar and incubated at room temperature (250C).
Both Candida albicans and spores of Aspergillus brasiliensis are inoculated on Potato Dextrose Agar or Sabouraud Dextrose Agar, incubated at room temperature (250C) and observed for growth
This can be a culture media with nothing inoculated on
DISCUSSION ON PROBABLE RESULT AND SIGNIFICANCE OF STERILITY AS INDICATOR OF PERFORMANCE
If growth is observed on the media on which the autoclaved filter paper or carrier is placed within 14 days of incubation under the proper hygienic laboratory condition. The autoclaved will be said to be faulty and term a poor sterilizer and might not be released into market until the issue is fixed. This will be done in comparison with the positive and negative controls. However, a second test might be needed to be carried out to confirm or ascertain the autoclave sterility performance.
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