33 - Sterilization and Disinfection

Question 1

how does microbial death occur?

Answer 1

exponentially, not all at once

Question 2

what will help the probability of a microbial kill?

Answer 2

increase concentration (number of “bullets” used/unit time) and decrease in number of targets still alive

Question 3

T/F the last 9 microbes will die faster than the first 900,000

Answer 3

FALSE, it takes just as long to kill the last 9 as the first 900,00! the more you start with, the harder it is to kill them all

Question 4

what term:
removing or killing all viable forms of organisms, even bacterial spores

Answer 4

sterilization

Question 5

what term:
eliminating most organisms, usually from surfaces (with varying levels)

Answer 5

disinfection

Question 6

what term:
reduction of harmful microbes on animal or plant tissues

Answer 6

antisepsis

Question 7

sterilizing agents must be _____________

Answer 7

microbicidal

Question 8

how does microbistatic affect microorganisms

Answer 8

prevent growth; growth can continue when agent is removed

Question 9

which items must be sterilized

Answer 9

critical items: items that penetrate sterile tissues (e.g. surgical instruments, implants, I.V. catheters)

Question 10

which items need at least high-level disinfectant

Answer 10

semicritical items: contact mucous membranes or nonintact skin (e.g. endoscopes, endotracheal tubes, cystoscopes)

Question 11

which items must be wiped with intermediate-level disinfectant

Answer 11

clinical contact items: contaminated during pt care (e.g. light handles, switches, x-ray equipment, drawer handles, pens, etc)

Question 12

which items mus be cleaned with EPA-registered detergent and water

Answer 12

housekeeping items (e.g. floors, walls, sinks)

Question 13

how does the physiological state of the organism affect susceptibility?

Answer 13

actively growing org. or cultures more susceptible than older stagnant ones

Question 14

what properties of the organism’s environment will affect the susceptibility?

Answer 14

temp, pH, viscosity of solutions, and presence of organic materials

Question 15

T/F boiling is not good as it doesn’t kill spores

Answer 15

true

Question 16

what is standard autoclave conditions

Answer 16

121 degrees C, 15 psi, for 15 min (“important to know standard autoclaving procedure”)

Question 17

how long does a dry heat oven take? what temp does it need?

Answer 17

1-16 hrs, needs higher temp (up to 171 degrees C)

Question 18

T/F low temperatures are usually good as they are microbicidal

Answer 18

False, low temp is usually microbistatic

Question 19

how does ultraviolet radiation (e.g. sunlight, UV lamps) do to microbes

Answer 19

induces cross-linking in nucleic acids
causes mutations
the problem: little penetrating power

Question 20

ionizing radiation such as ___________ and __________ will cause a break in nucleic acids, mutations and penetrates well but can be dangerous

Answer 20

gamma rays, X rays

Question 21

which chemical sterilization:
penetrates well, works on wrapped materials
good for heat-sensitive plastics, equipment
very toxic, can explode
requires at least 4-6 hr to work + hrs to detoxify

Answer 21

ethylene oxide (gas sterilization)

Question 22

which chemical sterilization:
cross-link DNA (stops replication)
low cost, no special equipment
requires immersion for 6-10 hrs at room temp
carcinogenic, causes hypersensitivity

Answer 22

aldehydes

Question 23

which chemical sterilization:
uses vaporized hydrogen peroxide
adds microwave or radio-frequency energy
produces free radicals that damage nucleic acids
no toxic byproducts

Answer 23

plasma gas sterilization

Question 24

which alcohols are most common fro chemical disinfection

Answer 24

ethyl and isopropyl (use at 70-95% concentrations)

Question 25

T/F ethyl and isopropyl are used to sterilize

Answer 25

False, won’t kill spores, some fungi, and some viruses such as norovirus

Question 26

mechanism of disinfection of H2O2

Answer 26

oxidizing agent - inactivates proteins
damages enzymes
active form is free hydroxyl radical
high-level disinfectant when concentrated (3-6% generally)

Question 27

con of disinfection with H2O2?

Answer 27

loses potency during long-term storage

Question 28

Iodine precipitates _____________

Answer 28

proteins

Question 29

what is iodophores used for?

Answer 29

wound antisepsis, preop skin conditioning, disinfect surfaces and equipment

Question 30

what will phenols do during chemical disinfection?

Answer 30

disrupt lipid membranes

Question 31

what is the chemical disinfectant in chlorhexidine?

Answer 31

derivative of phenol (carbolic acid)

Question 32

T/F phenols will kill fungi, mycobaterium spp., many viruses, and bacterial spores

Answer 32

FALSE! everything true but they don’t reliably kill bacterial spores

Question 33

what’s an example of what chlorine can kill

Answer 33

HIV, hepatitis viruses, recommended for norovirus outbreaks

Question 34

__________ will disrupt membrane function

Answer 34

detergents

Question 35

how do you monitor efficacy of sterilizers/autoclaves?

Answer 35

spore strips & chemical test strips

Question 36

alcohol based hand sanitizers need to have >_______% alcohol

Answer 36

60

Question 37

how long should alcohol based hand sanitizers be in contact with skin?

Answer 37

15-20 sec

Question 38

T/F alcohol based hand sanitizers are no effective against COVID

Answer 38

false