Micro: Antisepsis and Sterilization Flashcards
Who is the Dr. that determined that Docs should wash hands before going from one labor room to the next?
Ignaz “the vag magnet” Semmelweis
_______ infections are those whose onset and confirmation occur greater than 48 hrs after hospital admission.
Nosocomial infections (hosp. acquired)
Healthcare-associated infections differ from nosocomial infections in that they are the result of _______ , not simply those that are found within 48 hrs of admission (i.e. those contracted simply from the environment of a hospital)
Treatments or long-term residence
The single most important method to limit transmission of nosocomial agents is __________________.
proper hand hygiene
A _________ is a physical or chemical agent used to inhibit or destroy microorganisms on inanimate objects.
Disinfectant
An ________ is a physical or chemical agent used to inhibit or destroy microorganisms on skin or other tissue.
antiseptic
Do Disinfectants and antiseptics eliminate potential pathogens?
No, they reduce them.
________ agents inhibit bacterial growth.
Bacteriostatic
________ agents destroy or inactivate bacteria.
Bactericidal
How do phenolics and alcohols kill bacteria? Are they effective against spores, protozoan cysts and certain non-enveloped viruses?
Denature proteins and disrupt cell membranes. Not effective against spores, protozoan cysts and certain non-enveloped viruses.
Is isopropyl alcohol’s action fast or slow?
Slow
How does chlorhexidine kill bacteria?
alters membrane permeability (topical phenolic)
Is pure alcohol an effective antimicrobial?
No, most alcohol solutions are diluted with water to 70-95% strength.
How does iodine, a halogen, work as an antiseptic?
Works by iodinating or oxidizing bacterial proteins.
How does chlorine, a halogen, work as an antimicrobial?
Oxidizes bacterial proteins
________ are effective against bacteria, spores and most viruses and are therefore more effective than phenolics or alcohols.
Halogens
How do surfactants kill bacteria?
perturb bacterial cell membranes leading to cell death due to hydrophobic and hydrophilic groups.
Glutaraldehyde is an alkylating agent used to disinfect equipment. How does it work?
First polymerizes and then binds to proteins in the outer membrane of gram neg. bacteria and amino acids found in the peptidoglycan cell wall of gram pos. bacteria. The subsequent alkylation inactivates the proteins, killing the cells.
This is an alkylating, gaseous agent used to treat heat-labile equipment. It thoroughly kills (sterilizes) all contaminants.
Ethylene oxide gas
Several chemical agents are capable of oxidation, but ______ ______ acts solely in this manner.
Hydrogen Peroxide
How does hydrogen peroxide kill bacteria?
It attacks the lipid membrane and other cellular components, but is less effective against spores and cat-positive bacteria.
What is the only chemical agent capable of completely eliminating all contamination (sterilization)?
Ethylene oxide gas
________ is the complete killing or removal of all living organisms from an item or area.
Sterilization
List the 4 physical methods of bacterial control.
heat, cold, filtration, radiation
What kills more rapidly, moist heat or dry heat and why?
Moist heat, reactive water molecules denature protein by disrupting hydrogen bonds formed between AAs.
Autoclaving at _____ PSI and ______ Celsius for ____ minutes will kill all bacteria, fingi and viruses.
15 PSI, 121 Celsius, 15 minutes
Is the 15 PSI, 121 Celsius, 15 minutes rule for autoclaving adequate for spores and cysts?
No, time is extended.
Minimum temp and time standards for dry heat sterilization are:
160 Celsius for 2 hrs. This is because dry air does not conduct heat as well as moist air.
Does boiling objects sterilize them?
No. But does kill most non spores/cysts within 10 mins.
Describe pasteurization. Does it sterilize?
Heat liquid to 55-75 Celsius for 30 mins, then rapidly cool. Does not sterilize, bacterial load reduced by 90%.
Does freezing sterilize?
No.
Cellulose membrane filters, with pore sizes as small as ____ microns (um) are able to remove live and dead bacteria from liquids.
0.2 um
Do viruses pass through a 0.2 um filter?
Yes
________ ________ such as UV radiation is sterilizing because it ______ ________ and leads to the formation of new covalent bonds, such as thymine-thymine dimers in DNA.
Nonionizing radiation; excites electrons
Due to this property of nonionizing radiation, it has poor penetration properties, thereby limiting its usefulness.
Long wavelength
Nonionizing radiation is typically used to disinfect ______ and _______ in hospitals.
air, surfaces
What properties of gamma (ionizing) radiation make it better for kill bacteria embedded within tissues/structures?
Shorter wavelengths
How does gamma radiation kill bacteria?
Transmitted energy damages DNA but also produces free radicals and creates hydrogen peroxide from cytoplasmic water.
