Chapter 13 Flashcards
Control of Microbial Growth
Process of removing & destroying all microbial life
Sterilization
Procedure in which added precautions are used to
prevent contamination of a person, object or area by microbes
Sterile (aseptic) technique
Destroying harmful microorganisms; use
disinfectants
Disinfection
Destroying harmful microorganisms from living
tissue; use antiseptics
Antisepsis
Lowering microbial counts on eating utensils to safe
levels
Sanitization
Infected by contact or association
Contamination
Killing of microbes
Microbiocidal
Inhibiting, not killing, microbes
Microbiostatic
Time (in minutes) required to kill 90% of bacterial population at given temperature: also called D value
Decimal reduction time (DRT)
Time during which all cells in culture are killed
Thermal death time (TDT)
Process of mild heating to kill particular spoilage
microorganisms or pathogens
Pasteurization
What does the effectiveness of treatment depend on?
- # of microbes
- Environment
- Time of exposure
- Microbial characteristics
What are the physical methods of microbial control and how they kill microbes?
Heat- Kills microbes by denaturing proteins
Cold- Inhibits microbes
Desiccation- Removal of water & prevents metabolism
Radiation- Damages DNA
Filtration- Physically removes microbes
What are the categories of disinfectants and how they kill microbes?
Phenolics- Disrupt plasma membranes & denaturing proteins
Heavy metals- Denature proteins
Halogens- Very strong oxidizers
Alcohols- Denature proteins & dissolve lipids (disrupt membranes)
Surfactants- Any compound that decreases tension between molecules lying on surface of liquid; emulsification
Alkylating agents- Inactivates enzymes & nucleic acids
What is the purpose of the disk diffusion test?
Determine microbial susceptibility to chemotherapeutic agents
What type of microbe is most resistant to disinfection and autoclaving?
Prions
