microbiology: destruction,sterilisation and disinfection of microorganisms

Question 1

define decontamination

Answer 1

Is a combination of processes that removes or destroys contamination so that infectious agents or other contaminants cannot reach a susceptible site in sufficient quantities to initiate infection or other harmful response

Question 2

define sterilisation

Answer 2

complete killing of all types of microbes including spores

these can turn into spores aka vegetative spores

Question 3

what is another name for spores

Answer 3

vegetative spores

Question 4

give examples of eukaryotes

Answer 4

fungi

protozoa

Question 5

give examples prokaryotes

Answer 5

bacteria eg vegetative ones, spore producing ones

Question 6

give examples of viruses

Answer 6

herpes simplex virus and hepatitis

Question 7

what are the methods of sterilisation

Answer 7

heat can be

dry or wet

Question 8

how do we moist heat something

Answer 8

boiling, autoclaving and exposure to superheated steam at a controlled pressure and temperature cycles

Question 9

how do we sterilise instruments

Answer 9

using autoclaves is the gold standard

Question 10

what cycles can we use in the autoclave

Answer 10

115 digress for 30 mins
121 degrees for 15 mins
134 degrees for 3 mins

Question 11

what type of air displacement method do we use for wrapped instruments

Answer 11

vacuum type b

Question 12

what type of air displacement do we use for unwrapped instruments

Answer 12

passive type N

Question 13

how do we check if the sterilisation technique is complete

Answer 13

by a bowie dick test

Question 14

if the sterilisation test is complete and passed how should the bowie dick test turn out

Answer 14

the square should just be black and white

Question 15

if the sterilisation test is complete and failed how should the bowie dick test turn out

Answer 15

the square should be black and white with a yellow circle in the middle

Question 16

what are some cycles we can use for dry heat sterilisation

Answer 16

oven controlled temperature cycles
160-170 degrees for 120 minutes
170-180 degrees for 60 mins
180-190 degrees for 30 mins

Question 17

what are some disadvantages of the dry heat sterilisation technique

Answer 17

Time consuming method
Slow microbial killing
High temp is not suitable for most materials

Question 18

which method of sterilisation is more efficient

Answer 18

moist sterilisation is more effective

Question 19

when might dry heat technique be better than moist heat technology

Answer 19

▪ Such as with metals that can become corroded and sharp instruments
▪ Used for delicate metals which would corrode if used with steam
Or glassware

Question 20

how do we remove c botulism spores

Answer 20

in the saturated steam environment for 5 mins at 121 degrees
but in a dry hear they need 2 hours at 160 degrees

Question 21

give examples of chemical sterilisation

Answer 21

using liquid/gas
using ethylene oxide
highly flammable gas mixed with co2 to stop it burning

Question 22

what is the disadvantages of chemical sterilisation

Answer 22

takes a long time to dissolve from substances

Question 23

what is the issue with using glutaraldehyde

Answer 23

very toxic

Question 24

what is the issue with formaldehyde

Answer 24

vapour can reach inaccessible parts

Question 25

what is the benefit with using formaldehyde

Answer 25

useful for large equipment

Question 26

how does irradiation sterilise equipment

Answer 26

damage to the DNA and leading to cell death

Question 27

how does gamma radiation sterilise equipment

Answer 27

cold sterilisation

can go through objects with high efficiency

Question 28

how does filtration sterilise equipment

Answer 28

Removal of microorganisms in liquid that are destroyed by heat
Used to clarify liquids or gasses
Membrane filters made from nitrocellulose are made with micro pores to effectively to prevent the passage of microorganisms- useful for enzymes which would be denatured with high heat

Question 29

what is the issue with using chemical disinfection

Answer 29

that bacterial endospores are not killed by this method

Question 30

what is the issue with using sodium hypochlorite and iodine as disinfectants

Answer 30

Naclo- highly irritant

iodine- less reactive

Question 31

what do we need to do before we disinfect

Answer 31

clean object
make up the fresh disinfectant
correct concentration
do not mix with other chemicals

Question 32

what is chemical disinfection limited to

Answer 32

→ Environmental decontamination
→ Antisepsis
Heat sensitive items

Question 33

define antisepsis

Answer 33

disinfection applied to damaged skin and living tissues

Question 34

describe sanitation

Answer 34

removal of microbes that pose a threat to public health

Question 35

which patients are at risk for transmissible spongiform encephalopathies

Answer 35

Symptomatic or at risk
Risk of transmission is through neurological and lymphoid tissues or surgical instruments
Definite, probable, possible CJD

Question 36

what causes transmissible spongiform encephalopathies

Answer 36

prions

Question 37

where can prions be transmitted from

Answer 37

dental scalers

dentists hands