Lecture 24 - Sterilsation And Infection Flashcards Preview

MIIM20002 - Microbes, Infections, Responses > Lecture 24 - Sterilsation And Infection > Flashcards

Flashcards in Lecture 24 - Sterilsation And Infection Deck (40):
0

Where do microorganisms come from?

Hospital environment (instruments, fluid, air, medication)
Invasive devices (IVs, endoscopes, catheters)
Patient's own flora
Other people

1

How can we break the chain of infection?

1\ aseptic technique
2\ antibiotics
3\ Immunisation
4\ Hand washing
5\ Isolate the patient

2

What can we do to the host to break the chain?

Immunisation
Antibiotics

3

How can we target entry to break the chain of infection?

Aseptic technique

4

How can we target transmission to break the chain of infection?

Handwashing
Aseptic technique

5

How can we target the source and pathogen to break the chain of infection?

Sterilising
Isolation of patient

6

What is aseptic technique?

Procedures that minimise transfer and contamination with potential pathogens

7

What are the standard (universal) precautions?

Don't know what the patient has, but we use these precautions just incase

Protective equipment
- masks
- gloves
- gowns
- eyewear

When coming into direct contact with blood, mucous membranes, cuts, bodily fluids

8

What are the additional precautions?

Minimising risk of cross infection

- single room accommodation (isolation)
- special air filtration
- special respiratory masks
- restricted movement

9

Why do we encourage hand washing?

Very effective at stopping the spread of organisms

However, not everyone complies

10

When do we use standard precautions?
What about additional precautions?

Standard:
- all the time

Additional:
- M. tuberculosis
- influenza

11

When do we use positive and negative pressure rooms?

Positive pressure: highly immunocompromised patient

Negative pressure: TB patients

12

What are the improvents made in hand hygiene?

Washing: time consuming
Alcohol hand gels: better compliance
DeBug: Austin hospital, even better compliance

13

What has increased use of antibiotics in hospitals lead to?

Antibiotics resistance:

MRSA
VRE
Acinetobacter spp.
ESBL Klebsiella, E. coli

14

How can we stem emergence of resistance?

Prudent use of antimicrobials

15

What do plasmids often carry?

Genes for multiple resistance
Transfer

16

How does prudent use help?

Avoids selection of mutants

Avoid selection of certain bacteria in the gut

Minimise risk of antibiotic associated diarrhoea (C. difficile)

17

How can we prevent the spread of infection?

Vaccination

18

What does disinfection do?

Removes pathogens from an article

19

What happens when we wash our hands?

Removal of pathogens that have been transiently picked up

We aren't removing the normal flora that are always there

20

What is sterilation?
How is this different from sterilisation?

Removal of all living micro-organisms, spores and infectious agents

Wipes out the normal flora as well

21

What do we call the things that we use for disinfectants?

Disinfectants

22

What is the difference between biocidal and biostatic?

Biostatic: prevents growth. When removed, they continue to grow

Biocidal: kills bacteria

23

How do we go about disinfection?

Washing
Hot water, steam
Chemical disinfectants (bleach, alcohols, chlorhexidine, phenols)
- different efficacy against different pathogens

24

How do we kill spores?

Must use bleach and washing to physically remove the spores

Alcohol is not sufficient

25

What so we need to think about when disinfecting?

- concentration
- appropriate agent
- appropriate conditions (pH and temperature)
- adequate contact: physical and time

26

How do we perform sterilisation?

Heat: steam (autoclaves), hot air oven
Filtration: if it is a liquid we are sterilising
Chemical: H2O2, halogens, per acetic acid
Ionizing radiation: for plastic etc.

27

What do we need to think about when sterilising?

- type of contamination
- rate of biocidal action
- level of assurance

28

How do we determine the level of contamination?

Viable count

1. Dilute out bacteria
2. Spread out bacteria on media
3. Incubation
4. Count the colonies
5. Determine initial microbial load

29

When do we want to mostly affect the bacteria?

In log growth phase

30

What is the D value?

Time taken to reduce the population tenfold (90%) at a particular temperature

Decimal reduction time

31

What is sterility assurance?

Probability that a microorganism will survive the killing process

32

How do we decide on the sterility that is required?

Think about the function of the thing

For example
Bandaid: can accept a lower sterility assurance: 1/1000
Syringe: require higher sterility assurance: 1/1000000

33

Describe the sterilisation cycle

Preparation
Penetration
Holding
Safety margin
Cool down / drying / aeration

34

What is the sterilisation time?

Penetration + holding

35

How does heat kill microbes?

Physical and chemical change
Dry: oxidation
Moist: coagulation

36

Which type of heat is more effective?

Moist heat

Because liberates intense latent heat
Contract is volume --> draws in more heat

37

Is heat sterilisation good?

- Reliable and available
- economical
- the material must be stable

38

What can't we use moist heat for?

Things at risk of Corrosion

Metals

39

What can we use dry heat for?

Oils, solids, metals