21:02 Microbiology for Health Sciences Exam 3 Notes October 22, 2012 Chapter 12 Sterilization and Disinfection PRINCIPLES OF STERILIZATION AND DISINFECTION Sterilization Sterilization is the killing of all microorganisms in a material or on the surface of an object A surface or an object is either sterile or it is not sterile, there are no gradations in sterility Typically the last things to dies when one attempts sterilization is the highly heat- (and chemical-, etc) resistant endospores Sterility means there are no living organisms in or on a material Disinfectant A disinfectant is a chemical or physical agent that is applied to inanimate objects to kill the microbes Disinfection Disinfection means reducing the number of viable microorganisms present in a sample Not all disinfections are capable of sterilizing, but, of course all disinfections are employed with the hope of disinfecting Antiseptic Typically an antiseptic is a chemical agent that is applied to living tissue to kill microbes Note that not all disinfectants are antiseptics because an antiseptic additionally must not be so harsh that it damages living tissue
With this constraint imposed on antiseptics, in general antiseptics are either not as cheap or not as effective at killing microbes as disinfectants Table 12-1 Terms Related to Sterilization and Disinfection Term Definition Sterilization The killing or removal of all microorganisms in a material or on an object Disinfection The reduction of the number of pathogenic microorganisms to the point where they pose no danger of disease Antiseptic A chemical agent that can safely be used externally on living tissue to destroy microorganisms or to inhibit their growth Disinfectant A chemical agent used on inanimate objects to destroy microorganisms. Most disinfectants do not kill spores Sanitizer A chemical agent typically used on food-handling equipment and eating utensils to reduce bacterial numbers so as to meet public health standards. Sanitization may simply refer to thorough washing with only soap or detergent Bacteriostatic agent An agent that inhibits growth of bacteria Germicide An agent capable of killing microbes rapidly; some such agents effectively kill
certain microorganisms but only inhibit the growth of others Bactericide An agent that kills bacteria. Most such agents do not kill spores Viricide An agent that inactivates viruses Fungicide An agent that kills fungi Sporocide An agent that kills bacterial endospores or fungal spores
The Control of Microbial Growth Exponential death The killing of microorganisms occurs exponentially where some fraction of the living
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