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Unformatted text preview: 1 Microbiology Exam 2 Study Guide Chapter 10: Sterilization, Disinfection and Antisepsis: Definitions: Sterilization use of physical procedures or chemical agents to destroy all microbial forms, including bacterial spores Disinfection use of physical procedures or chemical agents to destroy most microbial forms; bacterial spores and other resistant organisms (mycobacteria, viruses, fungi) may remain viable; divided into high, intermediate, and low-level agents Antisepsis use of chemical agents on skin or other living tissue to inhibit or eliminate microbes; no sporicidal action is implied Germicide chemical agent capable of killing microbes; spores may survive Sporicide germicide capable of killing bacterial spores Sanitation process by which microbial contamination on inanimate surfaces is reduced to a “safe” level Sanitize wash De-germ remove some germs Relative Resistance: Most Resistant Forms Moderate Resistant Forms Least Resistant Forms Bacillus spp Pseudomonas spp (chemicals are tested on them – somewhat harder to kill) vegetative cells Clostridium spp Staphylococcus aureus (chemicals are tested on them – somewhat harder to kill) yeast cells Candida albicans – chlamydospores (takes more than soap and water) Trophozoites (protozoans) Giardia cysts in water enveloped viruses Hepatitis B HIV non-enveloped viruses Non-Enveloped Viruses: Enveloped Viruses: Practical Concerns in Microbial Control: is sterilization necessary? – sometimes is disinfection necessary? – usually match the method or agent to the material cost and labor involved safety of the procedure 3 levels of disinfection considered: high level – items that are invasive intermediate level – items that contact mucosal surfaces low level – items that will only be in skin contact 2 exception – relative risk the surfaces poses Methods of Sterilization: steam under pressure: temps above boiling point of water must consider the size and shape of the item for times and temps standards for small items: 121 C; 250 F; 15 minutes minimum items that can not be penetrated by steam can not be sterilized by moist heat examples: oils, powders items can be destroyed or “reformed” by moist heat examples: plastics works by coagulating the essential proteins of cells dry heat: can use common oven standards: 160 C, 320F, 2 hours minimum need more time for penetration thru materials wet items can not be sterilized by dry heat works by oxidation of essential proteins of cells moist heat is more efficient...
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- Spring '08
- Bacteria, Staphylococcus aureus, bacteremia