Sterilization Monitoring Using Biological Indicators
In order to ensure that the autoclave machine is functioning properly and sterilizing appropriately, biological indicators will be used. Biological indicators are contains a spore disc inoculated with bacterial spores (Geobacillus stearothemophillus) for steam sterilization and a culture medium, containing a pH indicator, encased in a crushable, glass ampoule. The acid production associated with growth causes a change in colour of the biological indicator. This aids in the detection of growth.
Methods
- Place one or more vials in the most difficult location to sterilize and run the cycle. Usually at 121°C for 15mins.
- Seal the cap immediately after retrieving the vials by pressing down firmly until flush with tube.
- Allow the tubes to cool. Purpose of cooling is to prevent bursting of ampoule due to heat and pressure.
- Crush the media ampoule by squeezing the sides of the tube.
- Ensure that the spore disc has been completely saturated with the growth media. If not, gently tap it on a hard surface until disc is totally immersed in the media.
- Incubate tubes at 55°C for 48 hours, checking at 24hrs interval. A control should be incubated together with those sterilized tubes.
Results
Control: Yellow
Sterilized Vials: Purple
If the vials that were sent for sterilization turn yellow (original colour is purple), it shows that the autoclaving/ sterilization process failed.
that's all! =)
Suat Fang
tg01
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7 comments:
Hey Gal!!!
thats a short post!haha..!
Charmaine
TG01
Hey,
I didn't know such thing existed, hehe. Anyway, is this a criteria to get accreditation, or just to test the autoclave machine is really working?
sorry for the stupid ques, bcoz i have never seen people testing the autoclave machine before.
thanks!
Nisha
TG02
Hello,
May I know what do you meant by placing the vials 'in the most difficult location to sterilize'? Care to elaborate more?
Thanks.
-Alex Tg02
Hey Xue Fang
Can other types of bacterial spores be also used apart from Geobacillus stearothemophillus?
Thanks =)
Eugene Wong
TG02
hey fang, urm is there any possible reasons that might cause the autoclaving/ sterilization process to fail? e.g human error?
then how you go bout it if it failed? re-run it agn?
Natalie
TG01
Hi Nisha
Is to ensure that the autoclave machine is really working. especially when pathogens or derivatives of pathogens are present, we must ensure that after autoclaving, they are being killed. so this is done by adding the BI to indicate the process is going on well.
Hi Alex
for our lab, the BI is usually placed in the centre among the many bags of waste. we consider that the "most difficult location to sterilze".
Hi Eugene
another kind of bateria spores that can be used is bacillus atrophaeus. for this bacteria it is being incubaed at 30-35 degree celsius instead.
Hi Nat!!
one of the possible reasons for autoclaving process to fail( ie the BI showing positive results after autoclaving) could be because the bag is being sealed too tight. by sealing the bag too tight, the steam cant penetrate through the bag, thus causing the sterilization process to fail. cycle will have to be re run if it fails, especially if pathogens ar involved.
Suat Fang
tg01
Hi,
Biological indicators that monitor the effectiveness of the steam sterilization process and provide results within 24 hours. It can also create custom indicators to meet your unique sterilization monitoring requirements. Thanks a lot...
Sterilization Indicators
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