BIOL125_Ch11 Notes

BIOL125_Ch11 Notes - BIOL 125(Microbiology Text and Lecture...

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BIOL 125 (Microbiology) Text and Lecture Notes Chapter 11: Physical and Chemical Agents for Microbial Control 11.1. CONTROLLING MICROORGANISMS a. General Considerations in Microbial Control i. Decontamination Procedures – general category describing methods of microbial control. 1) Methods include physical agents (ex. heat, radiation), chemical agents (ex. disinfectants, antiseptics), and mechanical removal methods (ex. filtration). ii. Lecture Notes 1) Decontamination – general term used to describe the process by which microorganisms are destroyed or removed to reduce the number to a minimum from an inanimate surface or medical device that touch live tissue such as mucous membrane. a) Decontamination minimizes the risk of food spoilage or infection. b) There are two types of decontamination: disinfection and sterilization. b. Relative Resistance of Microbial Forms i. General resistance of specific forms to physical and chemical methods of control: 1) Highest Resistance – prions; and bacterial endospores. 2) Moderate Resistance – protozoan cysts; some fungal sexual spores (zygospores); and some viruses (naked viruses are more resistant than enveloped forms). 3) Least Resistance – most bacterial vegetative cells; fungal spores (other than zygospores) and hyphae; enveloped viruses; yeasts; and protozoan trophozoites. ii. Because of the resistance to control, the destruction of bacterial endospores is the goal of sterilization. This is because any process that kills endospores will invariably kill all less resistant microbial forms. c. Terminology and Methods of Microbial Control i. Sterilization 1) Sterilization – process that destroys or removes all viable microorganisms, including viruses. 2) Methods that sterilize are generally reserved for inanimate objects, because sterilization of the human body would be dangerous and impractical. File: 80e3c9921ea485de84b4ea25c0b6f84ea7e44db0.doc Updated 8/14/09
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Microbiology Text and Lecture Notes Chapter 11 - Physical and Chemical Agents for Microbial Control Page 2 3) A Note About Prions a) Prions are extraordinarily resistant to heat and chemicals. b) Instruments or other objects contaminated with prions must be discarded as a biohazard or decontaminated with a combination of chemicals and heat in accordance with CDC guidelines. 4) Sterilants – a few chemicals that act as sterilizing agents because of their ability to destroy endospores. ii. Microbial Agents 1) The rood “- cide ” means to kill. 2) Virucide – chemical known to inactivate viruses, especially on living tissue. 3) Sporicide – agent capable of destroying bacterial endospores. A sporicide can also be a sterilant. iii. Agents That Cause Microbistasis 1) Bacteriostatic – agents that prevent the growth of bacteria. a)
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This note was uploaded on 08/12/2009 for the course BIOL 125 taught by Professor Dr.sujathapamula during the Spring '09 term at San Jacinto.

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BIOL125_Ch11 Notes - BIOL 125(Microbiology Text and Lecture...

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