Chemical and gas
1. Referred to as cold sterilization
Halogens agents (chlorine,iodine), Quaternary ammonium compounds,
Heavy metals (Ag,Cu, Hg, Zn), Oxidizing agents, Aldehydes, Alcohols, Phenolics, Ethylene Oxide
2. Chlorhexidine is similar to hexachlorophene.
a) Chlorhexidine is often combined with detergents or alcohol as a disinfectant of skin.
b) Effective disinfectant of most vegetative bacteria and enveloped viruses.
c) Used in surgical hand scrubs.
Gaseous Sterilizer:
Chemicals that sterilize in a chamber similar to an autoclave.
Denature proteins, by replacing functional groups with alkyl groups.
Ethylene oxide: kills all microbes and endospores, but requires exposure of 4 to 18 hours.
- Toxic and explosive in pure form
- Highly penetrating
Mechanical agents
A. Filtration
1.Mechanical means of removing microorganisms. The liquid or gas is passed through a filter with pores small enough to prevent passage of microbes. This method can be used for substances that are sensitive to heat.
- HEPA filter: removes at least 99.97% of airborne particles 0.3 micrometers in diameter.
- ULPA filter : remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles with a size of 120 nanometers or larger.
B. Osmotic pressure
1. Extremely hypertonic conditions can cause plasmolysis (i.e.,contraction of all the cell membrane away from the cell wall)
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