Antisepsis and Sterilization Flashcards
What are Koch’s postulates?
- microbe must be present in all disease cases
- microbe must be isolated from the infected host and grown in culture.
- when a pure culture is introduced into a susceptible host, the disease must be reproduced
- the microbe must be isolated from a purposely infected host.
*note these have been modified in modern times but the principles are similar
What is disinfection? how is that different from antisepsis or sterilization?
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What is a nosocomial infection?
those whose onset and confirmation occur greater than 48 hours after hospital admission. (Hospital acquired infections)
What is a healthcare-associated infection?
Similar to a nosomcomial infection, but doesnt necessarily have to happen in the hospital. Can occur within 6-12 months of systemic antibiotic treatment, residence in a long-term care facility, central IV, catherterization or dialysis.
Most effectively controlled by hand hygiene.
What is a disinfectant? How is it different from an antiseptic?
a physical or chemical agent used to inhibit or destroy microorganisms on inanimate objects.
antiseptics kill microorganisms on living tissues or skin.
What does bacteriostatic mean? Bactericidal?
sterilizing agent that simply inhibits bacterial growth, but doesn’t necessarily eliminate it.
Bactericidals kill or inactivate bacteria.
What are pehnolics?
phenols that denature proteins and disrupt cell membranes. Gnerally innefective against spores, protozoan cysts and certain non-enveloped viruses. They are often too toxic for prolonged exposure to skin but are the active ingredients in mouthwashes.
What is chlorhexidine?
a topical phenolic that alters the membrane permeability of bacteria
Describe isopropyl alcohol’s use as an antiseptic.
Has a slow action, but commonly used.
How does iodine work as an antiseptic?
iodinates or oxidizes bacterial proteins. Often packaged as iodophors.
How is chlorine used?
it is not suitable for antiseptic use, but is commonly mixed with water to clean it.
Which is more likely to kill bacteria and viruses: alcohol or halogens?
Halogens are effetive against bacteria, viruses, and spores.
Alcohol and phenols are usually only effective against most bacteria and some viruses. Innefective against spores.
What is asurfactant?
something that contains hydrophobic and hydrophilic groups. They perturb bacterial cell membranes and kill them.
What are ‘quats’ (quaternary ammonium compounds?
cationic deterbents used as antiseptics. Some bacteria can grow in them though. Also innefective against viruses so not used commonly.
What is glutaraldehyde used for?
sterilizing equipment.
What is ethylene oxide gas used for?
to treat heat-labile equipment. it is explosive, mutagenic and skin hazardous. It is the only chemical agent capable of true sterilization (complete removal of all living organisms).
What types of things are resistant to hydrogen peroxide?
spores and catalase-positive bacteria.
What is sterilization? How is it best accomplished?
complete killing or removal of all living organisms from an item or area. Best accomplished by physical methods
Why does moist heat kill more quickly than dry heat?
Firstly because condensation is an exothermic reaction and will generate extra energy. Second, reactive water denatures proteins by disrupting hydrogen bonds.
Will boiling an object sterilize it?
No, but it does kill most everything except spores or cysts within 10 minutes. This is because the temp can never exceed 100C unless you add pressure.
Does pasteruization sterilize?
no. It is heating liquids to 55-75C for 30 minutes followed by rapid cooling. Spores are not killed, but bacterial load is reduced by 90%, increasing storage life and making it safe for consumption.
Will freezing something sterilize it?
No. Even though slow freezing can lyse cells, it has zero effect on spores.
How are heat-labile liquids sterilized for lab or clinical use?
filtering with cellulose membranes. This removes bacteria but not viruses, which are too small.
Why is nonionizing radiation not very effective?
it has limited cell penetration. Useful for air and surfaces though. commonly used on disposable surgical equipment
