Disinfection and Sterilization Flashcards
define sterilization
killing off of ALL micro-organisms
define germicide
agent used to kill micro-organism
define disinfection
use of a germicide to destroy the infectivity of micro-organisms
define antisepsis
application of agents to the surface of teh HUMAN BODY to kill/inhibit pathogens
define septic
characterized by the presence of pathogenic bacteria in living tissue.
define aseptic
without pathogenic bacteria
define sanitize
lower the bacterial content of objects without necessarily killing all the bacteria. ie, dishes in soap and hot water.
define preservative
agent used in small concentrations to inhibit the growth of organisms in food or vaccines
define phenol coefficient. if higher than one, what does that mean?
measure of the killing capacity of an agent compared to phenol. based on effective concentration. an agent that works at a lower concentration than phenol has a coefficient greater than one.
an example of wet heat sterilization. why is wet heat better than dry heat?
autoclave. better because the heated water molecules disrupt H bonds and denature proteins.
autoclave: advantages and disadvantages?
adv: effective, complete sterilization. dis: complicated, expensive, can’t be used for heat-sensitive materials
wet hear v dry heat: what are the relative temps used?
wet heat: 121’C, dry heat 160’C.
describe Pasteurization. what is is used for?
heat treatment. usually used for milk now, and a test bacterium is checked for to make sure that other things (that will be killed at lesser temps) are gone.
advantages/disadvantages of filtration?
adv: non-destructive. dis: can be inconvenient, particularly if large volume.
adv/dis of radiation?
adv: simple to set up. dis: poor penetration into depths/thick items, can damage human tissue
How does radiation work to disinfect?
emits UV light, which is absorbed by nucleic acids and proteins. interferes with DNA replication.
describe gaseous sterilization. what is the chemical used?
Type of chemical sterilization. chemical = ethylene oxide. used to sterilize heat-sensitive materials (ie plastics). also surgical materials, bedding.
name two alcohols used for chemical disinfection
ethyl alcohol, isopropyl alcohol
discuss the use of ethyl alcohol vs. isopropyl alcohol
ethanol denatures proteins, most widely used. not reliable against all organisms. isopropyl alcohol is more potent, less volatile, but more expensive than ethanol. ethanol does NOT kill spores.
describe use of iodine
oxidizes the hydroxyl group of tyrosine residues. skin antiseptic, used for minor wounds. painful. can be used to prep skin for surgery.
describe use of cationic detergents
active against all types of bacteria, disrupting cell membranes and dissolving lipid films. leave a bacteriocidal film on surfaces of treated objects.
describe use of heavy metals for disinfection
a 1% solution of silver nitrate kills gonococcal organisms in the eyes of newborns. heavy metals bind to SH groups in proteins.
