Disinfection and Sterilization
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Introduction
Decontamination: cleaning to render safe to handle, in preparation for disinfection/sterilization
Disinfection: reduces number of microbes; differs in strength
Sterilization: elimination of all pathogens, save prions
Disinfectants
numbers reduced due to microbial death rate
logarithmic effect, with constant proportion given conditions. at low levels, bacteria may be inhibited rather than killed
mechanism of action is by protein denaturation, membrane damage, enzyme inactivation, etc
Disinfection Methods
antiseptics: disinfectants that can be used on hands
- alcohols
- iodophors (betadine)
- chlorhexidine
- triclosan
- phenolics: disrupt membranes and precipitate proteins
- alcohols (70%): denature proteins
- halogens: oxidizes enzymes
- activity drops once exposed to air
- quaternary ammonium compunds: possibly disrupt membranes
- heavy metals: copper, lead, silver
- may be used in ointments or medical devices
high level disinfectants: kill spores, tubucle bacilli, viruses given enough time; with sufficient strength, become sterilizing agents
- ortho-pthalaldehyde
- gluteraldehyde
- formaldehyde
- peracetic acid
- hydrogen peroxide
Sterilization Methods
heat (autoclave
gas, liquid
- ethylene oxide
- aldehydes
- ozone
- peracetic acid
- hydrogen peroxide
irradiation
filtration (does not stop viruses)
Resources and References
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