There are certain terms which are commonly used with respect
to infection control. It helps to know the definitions
Cleaning: Removal of visible soil using water with detergents or enzymatic products.
Disinfection: Elimination of many or all microorganisms except bacterial or fungal spores
Sterilisation: The complete removal or destruction of all forms of microbial life including spores. The efficacy of both sterilization and disinfection is affected by many factors: prior cleaning methods; the nature of the instrument or device (e.g. material properties; presence of a lumen or crevices etc.) the presence of biofilm on the device; the temperature, pH, and exposure time used; and in some cases, the humidity of the agent used to disinfect or sterilize.
Critical devices: A high risk of infection if contaminated eg. Surgical instruments, implants, needles etc. Should be steam sterilized or disposable (presterile).
Semicritical devices: instruments that come in contact with intact mucous membranes or non-intact skin. Susceptible to more virulent infectious agents. Eg. Applanation tonometers, Gonioscopes etc. Require thorough cleaning, followed by high-level disinfection to eliminate most organisms except some and spores. Reuse of semicritical instruments requires a high level of disinfection with sterilants/germicideal agents.
Noncritical items: Come in contact with intact skin, but not mucous membranes. They require cleaning and routine disinfection. Eg. Table tops, Chin rests etc.