Disinfection and Sterilization

Question 1

define sterilization

Answer 1

killing off of ALL micro-organisms

Question 2

define germicide

Answer 2

agent used to kill micro-organism

Question 3

define disinfection

Answer 3

use of a germicide to destroy the infectivity of micro-organisms

Question 4

define antisepsis

Answer 4

application of agents to the surface of teh HUMAN BODY to kill/inhibit pathogens

Question 5

define septic

Answer 5

characterized by the presence of pathogenic bacteria in living tissue.

Question 6

define aseptic

Answer 6

without pathogenic bacteria

Question 7

define sanitize

Answer 7

lower the bacterial content of objects without necessarily killing all the bacteria. ie, dishes in soap and hot water.

Question 8

define preservative

Answer 8

agent used in small concentrations to inhibit the growth of organisms in food or vaccines

Question 9

define phenol coefficient. if higher than one, what does that mean?

Answer 9

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.

Question 10

an example of wet heat sterilization. why is wet heat better than dry heat?

Answer 10

autoclave. better because the heated water molecules disrupt H bonds and denature proteins.

Question 11

autoclave: advantages and disadvantages?

Answer 11

adv: effective, complete sterilization. dis: complicated, expensive, can’t be used for heat-sensitive materials

Question 12

wet hear v dry heat: what are the relative temps used?

Answer 12

wet heat: 121’C, dry heat 160’C.

Question 13

describe Pasteurization. what is is used for?

Answer 13

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.

Question 14

advantages/disadvantages of filtration?

Answer 14

adv: non-destructive. dis: can be inconvenient, particularly if large volume.

Question 15

adv/dis of radiation?

Answer 15

adv: simple to set up. dis: poor penetration into depths/thick items, can damage human tissue

Question 16

How does radiation work to disinfect?

Answer 16

emits UV light, which is absorbed by nucleic acids and proteins. interferes with DNA replication.

Question 17

describe gaseous sterilization. what is the chemical used?

Answer 17

Type of chemical sterilization. chemical = ethylene oxide. used to sterilize heat-sensitive materials (ie plastics). also surgical materials, bedding.

Question 18

name two alcohols used for chemical disinfection

Answer 18

ethyl alcohol, isopropyl alcohol

Question 19

discuss the use of ethyl alcohol vs. isopropyl alcohol

Answer 19

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.

Question 20

describe use of iodine

Answer 20

oxidizes the hydroxyl group of tyrosine residues. skin antiseptic, used for minor wounds. painful. can be used to prep skin for surgery.

Question 21

describe use of cationic detergents

Answer 21

active against all types of bacteria, disrupting cell membranes and dissolving lipid films. leave a bacteriocidal film on surfaces of treated objects.

Question 22

describe use of heavy metals for disinfection

Answer 22

a 1% solution of silver nitrate kills gonococcal organisms in the eyes of newborns. heavy metals bind to SH groups in proteins.