Hi Al Jabri,

In my personal opinion, the answer to your question is “yes”.

The decontamination process involves 2 aspects:
1) Removal of soil (Organic & Inorganic), and
2) Killing of microbes

Once all the soil has been removed, the medical device is termed as ‘clean’. Once the cleaning process has been completed, only then, can the killing process be effective.

If the cleaning process is achieved mechanically (by use of validated washer disinfectors), it will be followed by a thermal disinfection process (Ao value of 600, 3000 or even more). This is termed as High Level Disinfection.
However, if the cleaning process is manual, it may be followed by a manual disinfection process (spray with 70% alcohol). This is low level disinfection.

As we are already aware, both the processes (disinfection & sterilisation) are killing processes. Disinfection is a process which kills all forms of vegetative microorganisms excluding spores. Sterilisation is a process which kills all forms including spores.

So, essentially, if a medical device is sterilised, it automatically achieves the aim of disinfection and sterilisation.

It may be mentioned herein that, while the patient is safe, the staff in the IAP area (inspection, assembly & packing) might have to be extra careful. The IAP staff needs to be aware that they are dealing with a medical device which is not high level disinfected.

I hope I have answered your question. Putting it simply, If a medical device has been cleaned and then sterilised (the disinfection process has been skipped), the medical device is termed as ‘sterile’

Kind Regards

Ravi Nayak

Thank you
Can you explain for me the
Ao value of 600, 3000 or even more). This is termed as High Level Disinfection.
as I no it’s low level disinfection
90c

Hi Al Jabri,

Ao value is an Activity co-efficient used to describe (or should I say, measure) the efficacy of the disinfection process using hot water.

For high level disinfection, it is said that a minimum Ao value of 600 is required. This means that the exposure time at 80 degrees Celsius is 600 seconds (10 minutes). The time temperature relation is as follows:

100 minutes at 70 degrees Celsius, or

10 minutes (600 seconds) at 80 degrees Celsius, or

1 minute at 90 degrees Celsius

Thus,
Exposure at 90 degrees Celsius for 5 minutes ensures an Ao value of 3000.

In the past 15 years or so, a temperature of 93 degrees is used more and more.

You may wish to check out websites of WFHSS, Robert Koch Institute, CHRISP Queensland etc to find out more

Kind Regards

Ravi Nayak

Thank you for the information