• Cleaning is the removal of foreign material, such as soil and organic matter from surfaces. This can be accomplished manually or mechanically using water with detergents or enzymatic products.
• Cleaning must be performed before disinfection and sterilization as soiled areas reduce the effectiveness of these processes.
• With manual cleaning friction and fluidics are essential. Friction involves rubbing or scrubbing soiled areas with a brush and fluidics involves the use of fluids under pressure which can be used to remove soiling from areas where a brush cannot reach.
• Disinfection is the process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects. Methods of disinfection involve liquid chemicals or wet pasteurisation. Wet pasteurisation is the heating of a wet material to 70°C for about 30 minutes.
• Commonly used disinfectants include alcohols, chlorine and chlorine compounds, formaldehyde, glutaraldehyde, ortho-phthalaldehyde, hydrogen peroxide, iodophors, peracetic acid, phenolics, and quaternary ammonium compounds. Commercial formulations based on these chemicals should be registered with the EPA for guaranteed effectiveness.
• High-level disinfectants can kill all microorganisms except large numbers of bacterial spores. Examples of these are >2.4% glutaraldehyde, 0.55% ortho-phthalaldehyde (OPA), 0.95% glutaraldehyde with 1.64% phenol/phenate, 7.35% hydrogen peroxide with 0.23% peracetic acid, 1.0% hydrogen peroxide with 0.08% peracetic acid, and 7.5% hydrogen peroxide 85. A more exhaustive list can be found here: http://www.fda.gov/cdrh/ode/germlab.html
• Intermediate-level disinfectants should kill mycobacteria, vegetative bacteria, most viruses, and most fungi but do not necessarily kill bacterial spores.
• Low-level disinfectants can kill most vegetative bacteria, some fungi, and some viruses.
• A germicide is an agent that can kill pathogenic microorganisms. The term germicide includes disinfectants and antiseptics.
– Antiseptics are germicides applied to living tissue and skin.
– Disinfectants are antimicrobials applied only to inanimate objects.
• Virucides, fungicides, bactericides, sporicides, and tuberculocides can kill the type of microorganism identified by the prefix. For example, a bactericide is an agent that kills bacteria.
• Sterilization is the process that eliminates all forms of microbial life by physical or chemical methods.
• Sterilizing agents include steam under pressure, dry heat, ethylene oxide gas, hydrogen peroxide gas plasma, and liquid chemicals.
• Factors that affect the efficacy of both disinfection and sterilization include:
– prior cleaning of the object
– organic and inorganic load present
– type and level of microbial contamination
– concentration of and exposure time to the germicide
– physical nature of the object (e.g., crevices and hinges)
– presence of biofilms
– temperature and pH of the disinfection process
– and in some cases, relative humidity of the sterilization processes.