Quality Control Process of the Autoclave

The quality control process for autoclaves is important to prevent the transmission of infection.

It is done to ensure that sterilization or decontamination by the autoclave​ is up to the mark.

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To ensure that biohazardous waste is properly decontaminated during autoclaving, the following procedures should be followed by laboratory personnel for quality control during autoclaving:

A. Use of Chemical Indicator

• With each load of sterilization, an autoclave tape needs to be used (Figure 1)
• The autoclave tape is a visible temperature sensitive chemical indicator, with stripes that change colour after proper autoclaving is done (Figure 2)

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Figure 1: Autoclave tape used on the load of material to be sterilized

Figure 2: Change in the colour of strips in the autoclave tape before and after proper autoclaving 

Note: Temperature sensitive autoclave tape is not sufficient on its own to indicate that the sterilization temperature (121ºC), is uniformly achieved throughout the chamber.  ​

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B. Biological Indicator (BI)​

Biological indicators are used for checking the quality of autoclaving on a monthly basis, even if the autoclave has a paper printed monitoring system for autoclave effectiveness. The results need to be documented and kept for at least one year. ​

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Principle of Biological Indicators

• Heat-resistant Geobacillus Stearothermophilus spores are used for autoclave efficiency testing
• After autoclaving, the autoclaved spore vial is incubated in a culture along with a non-autoclaved control vial at 56-60ºC
• The control biological indicator should yield positive results for bacterial growth and the autoclaved biological indicator should not show any growth (see Figure 3)

Figure 3: Showing effective use of the biological indicator

Figure 4: Steps to follow when using biological indicators

Reading and Recording

• Record details of the loading and of the autoclave’s operation in the autoclave logbook
• Incidents, accidents and/or mechanical problems must be recorded and reported to a supervisor immediately

Figure 5: Autoclave Logbook

Resources

• Tuberculosis Laboratory Biosafety Manual, 2012, WHO.
• Mycobacteriology Laboratory Manual, April 2014, WHO.
• Autoclave Quality Assurance Program, Biosafety Manual, Boston University.

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