Infection Control

Question 1

What is the best way to prevent the spread of bacteria from the hands? (2)

Answer 1

• Correct handwashing techniques

- Effective handwashing liquids

Question 2

How can the efficacy of toilet paper be assessed in preventing the transfer of bacteria?

Answer 2

Transfer bacteria from one agar plate to another using toilet paper as a barrier to prevent inoculation

Question 3

How can it be proven that hands are not sterile and are colonised by a wide variety of bacteria? (3)

Answer 3

• Take swabs from various hand sites before/after washing with liquids
• Effectively inoculate agar plate
• Produce culture

Question 4

Name 4 basic microbiology practices

Answer 4

• Not same swab for different areas: cross contamination
• Fresh swabs each time
• Discard contaminated material in yellow biohazard boxes
• Dispose of gloves in bins

Question 5

What parts of a bacteria can be damaged in order for it to be killed? (2)

Answer 5

• Damage to an essential cell structure

- Damage to a metabolic pathway

Question 6

What 2 methods are used/combined in clinical practice to kill bacteria?

Answer 6

• Heat

- Disinfectants

Question 7

What is a disinfectant?

Answer 7

Any chemical compound that kills bacteria or inhibits their growth

Question 8

What three skin disinfectants are used extensively in clinical practice?

Answer 8

• Alcohol-based hand gel
• Hibiscrub
• Betadine

Question 9

What two ways is oil removed from the hands in regular soap and water handwash? (2)

Answer 9

• Chemically: soap breaks down oil

- Mechanically: friction from rubbing

Question 10

How is the amount of oil and microbes left on the hands minimised? (2)

Answer 10

• More soap

- Longer the hands rubbed together

Question 11

How long do public health officials agree handwashing should be carried out?

Answer 11

20 seconds or more

Question 12

Does bacteria die when you handwash?

Answer 12

No, is flushed away in rinse/wiped off on towel

Question 13

What do alcohol based hand gels contain some combination of? (3)

Answer 13

• Isopropyl alcohol
• Ethanol (ethyl alcohol)
• N-propanol

Question 14

What percentage of alcohol should alcohol based gels contain to be most effective at killing many different kinds of bacteria/viruses in lab and human skin?

Answer 14

60-95%

Question 15

What does the killing action of alcohol based hand gels depend on?

Answer 15

Its concentration

Question 16

Does absolute alcohol kill bacteria?

Answer 16

No

Question 17

What two ways does alcohol kill bacteria? (2)

Answer 17

• Denatures proteins and nucleic acid

- Destabilises membrane

Question 18

What does hibiscrub disrupt in bacteria?

Answer 18

Cell membrane

Question 19

What type of bacteria does hibiscrub have bacteriocidal and bacteriostatic effects on? (2)

Answer 19

• Gram positive

- Gram negative

Question 20

What is the active ingredient in Hibiscrub?

Answer 20

Chlorhexidine

Question 21

How does chlorhexidine in Hibiscrub have a bacteriocidal and bacteriostatic effect? (2)

Answer 21

• Destabilises cell wall

- Interferes with osmosis

Question 22

How does chlorhexidine in Hibiscrub destabilise the cell wall?

Answer 22

The positively-charged molecule binds to the negatively-charged sites on the cell wall

Question 23

What is the bacterial update of chlorhexidine like?

Answer 23

Very rapid

Question 24

How does chlorhexidine kill bacteria in low concentrations? (4)

Answer 24

• Damages cell wall
• Crosses into cell
• Attacks cytoplasmic (inner) membrane
• Leakage of components leads to cell death

Question 25

Describe the cytoplasmic membrane of bacteria (2)

Answer 25

• Delicate

- Semi permeable

Question 26

How does chlorhexidine kill bacteria in high concentrations?

Answer 26

Causes cytoplasm to congeal/solidify

Question 27

What does betadine contain as an active ingredient?

Answer 27

Povidone-iodine (PVP-I)

Question 28

What two ways is betadine used? (2)

Answer 28

• Solution in water for cleaning minor wounds

- Surgical scrub for cleansing hands

Question 29

What type of bacteriocide is iodine?

Answer 29

Broad-spectrum

Question 30

What are the advantages of PVP-I (betadine) use in clinical practice? (3)

Answer 30

• Reduces irritation at application site
• Reduces toxicity
• Bacteria don’t develop resistance to it