When is it safe to use high level disinfection?

Disinfection is defined as the reduction in the number of viable microorganisms on a surface of a medical device, to a level previously specified.

Medical devices are disinfected in order to render them safe to use. Thermal disinfection is often used in washer disinfectors to render surgical instruments safe to handle after washing. Chemical disinfection is used to process semi-critical medical devices. Semi critical medical devices are devices that come into contact with intact mucous membranes or non-intact skin. Examples of semi-critical medical devices include flexible endoscopes, rigid endoscopes, and ultrasound probes. Surgical instruments that come into contact with a sterile cavity should rather be sterilized and not disinfected. Chemical disinfection is achieved by soaking a device in a disinfectant. There are various products available on the market that can be purchased to disinfect semi-critical medical devices. Disinfectant formulations may and sometimes do sound similar but they can vary in their antimicrobial activity (efficacy), surface compatibility and safety aspects.

Always follow the manufacturers’ instruction for use carefully when using chemical disinfectants. The manufacture will stipulate how long the device should soak for and how many times the device should be rinsed with sterile water afterwards. Always wash, rinse and dry instruments thoroughly before immersing them in the disinfectant. If this is not done the disinfectant can easily be diluted, and may no longer be effective.

Some disinfectants remain active for long periods of time whilst other disinfectants need to be mixed on a daily basis. There are advantages and disadvantages associated with this. Disinfectants that remain active for long periods of time may be become soiled with patient debris, may become diluted and are often ‘topped up’ which is not good clinical practice. Disinfectants that remain active for one day must be mixed on a daily basis.

It is safe to use high level disinfection if the manufactures instructions are followed precisely, and as long as only semi-critical items are being disinfected.