Microbio 4-2 disinfection and sterilization Flashcards Preview

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Flashcards in Microbio 4-2 disinfection and sterilization Deck (52)
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What is sterilization?

killing of all microorganisms (bacteria, fungi, viruses)


What is germicide? Fungicide? Virocide?

agent used to kill bacteria, fungi, and viruses


What is disinfection?

use of a germicidal, fungicidial, and virocidial chemical agent to destroy the potential infectivity of an inanimate object (ie floor)


What is antisepsis?

use of chemical agents on the surface of the body to kill or inhibit pathogenic bacteria


What does septic mean? Aseptic?

Septic = presence of pathogenic bacteria. Aseptic = absence of pathogenic bacteria.


What does santiize mean?

lowering of bacterial content of food utensils or similar objects, without necessarily killing all bacteria (ie dishes washed in soap)


What are preservatives?

agent used in small, non-toxic, concentrations to inhibit the growth of organisms (ex: lactic acid, acetic acid, propionic acid, benzoic acid)


What is phenol coefficient?

measure of the killing capacity of an agent compared to phenol. Coefficient is the ratio of the minimum killing [ ] of phenol over the minimum killing [ ] of the agent


What does a phenol coefficient >1 indicate?

agent works at a [ ] that is lower than that of phenol.


What are the 3 main physical agents that are used to kill bacteria?

1) heat (wet/dry), 2) filtration, 3) radiation


What is wet heat?

steam under pressure (ie autoclave)


Is wet heat more effective than dry heat? Why?

Yes. Because the water molecules speed up the protein denaturation


What is wet heat not suitable for?

heat-sensitive materials (ie plastics)


What settings would you change if you were to use dry heat instead of wet heat?

increase the temperature and time needed for sterilization


When is dry heat more appropriate than wet heat?

used when materials would be damaged by water (ie powders, special surgical dressings)


What is pasteurization? How is this different than flash pasteurization?

Pasteurization is essentially mild heating (63˚C for 30 min). Flash pasteurization essentially high temperature, short time (71-72˚C for 15-17 sec). Used in the treatment of wine, milk, juices etc


T/F Pasteurization does not kill spores.



When would you use filtration over heat?

when liquid material is sensitive to heat (ie it contains enzymes).


What are the advantages and disadvantages of using filtration?

Advantages: non-destructive. Disadvantage: inconvenient, esp if large volumes are involved.


What are the two types of radiation that is commonly used to sterilize objects?

non-ionizing radiation (ie UV light emitted by mercury vapor lamps), and ionizing radiation (x-rays, gamma rays).


How does radation work to sterilize objects? (2)

causes 1) thymidine dimers (interferes with DNA replication) 2) peroxide formation (toxic)


Pros and cons of using UV radiation to sterilize objects?

pros: easy to set up. Cons: poor capacity to penetrate anything but air and the thinnest layers of solids/liquids


What other physical forms other than heat, filtration, and radiation can be used to sterilize objects?

1) drying, 2) high osmotic pressure, 3) high sugar concentration


What are examples of some chemical methods used to sterilize objects? (9)

1) gas, 2) alcohol, 3) halogens, 4) detergents, 5) oxidizing agents, 6) phenols, 7) heavy metals, 8) dyes, 9) aldehydes, 9) preservatives


When is gaseous sterilization preferred over other methods of sterilization?

when sterilizing dry materials that are heat-sensitive (ie plasticware, surgical equipment, etc)


What is ethylene oxide?

gas that is used to sterilize heat-sensitive materials. Alkylating agent.


Ethylene oxide is an explosive agent and can only be used in the presence of this.

high concentrations of CO2


When is ethanol preferred over other methods of sterilization?

when using on skin before injections.


Does ethanol kill spores?

of course not.


What is tincture?

medicine made by dissolving a drug in alcohol