Infection Prevention and Control

Question 1

Retrospective vs prospective study?

Answer 1

In prospective studies, individuals are followed over time and data about them is collected as their characteristics or circumstances change.

In retrospective studies, individuals are sampled and information is collected about their past.

i.e. Retrospective (look back exercise). Prospective (more tests, awareness).

Question 2

What are the 6 steps in the chain of infection?

Answer 2

1. Pathogenic organism: Of sufficient virulence and in adequate numbers to cause disease
2. Reservoir: Reservoir or source that allows the organism to survive and multiply
3. Exit: Mode of exit from the source
4. Transmission: Mode of transmission from the source to the host
5. Entry: Portal of entry through which the pathogen can enter the host
6. Susceptible host (i.e. non-immune)

Question 3

Fill out the 6 steps in the chain of infection for MRSA:

Answer 3

1. Pathogenic organism: MRSA
2. Reservoir: Human skin particularly nose and other moist and hairy areas

3, 4, 5. Mode of transmission, exit and entry: direct contact with infected sites or indirect contact with fomites or hands of healthcare workers

6. Susceptible host: any breakdown in skin integrity

Question 4

Where is MRSA normally found?

Answer 4

Human skin particularly nose and other moist and hairy areas

Question 5

What is the aim of infection prevention and control (IPC)?

Answer 5

Activities undertaken with the aim of breaking the chain of infection e.g.:

• Eliminate pathogenic organism
• Remove source/reservoir
• Minimise transmission
• Eliminate exit and entry
• Reduce susceptibility to infection

Question 6

What is ‘phage typing’? What is it used for?

Answer 6

Phage typing is a method used for detecting single strains of bacteria. It is used to trace the source of outbreaks of infections.

Question 7

What is an outbreak?

Answer 7

Two or more linked cases of the same illness, when the observed number of cases exceeds the expected number or a single case of disease caused by a significant pathogen (i.e. viral haemorrhagic fever)

An outbreak investigation is then needed to determine mode of transmission and any breakdown in IPC practices.

Question 8

Which viruses commonly cause outbreaks in hospitals?

Answer 8

Influenza
Norovirus
SARS CoV-2

Question 9

Which bacteria commonly cause outbreaks in hospitals?

Answer 9

Clostridium difficile 
MRSA
Group A Streptococcus
VRE (vancomycin resistant Enterococci)
Multi drug resistant gram negatives ( ESBL, CPEs)

Question 10

Which fungi commonly cause outbreaks in hospitals?

Answer 10

Aspergillus

Question 11

All elective surgical patients should be screened for MRSA pre surgery.

1. Where are swabs taken from?
2. If positive, what happens?

Answer 11

1. nose, axilla and groin

2. Offered decolonisation if positive – mupirocin or neomycin and chlorhexidine body wash

Question 12

What perioperative measures are taken to prevent infection?

Answer 12

Perioperative antibiotics (with activity against MRSA if known positive)

Surgical skin prep

Scrub technique and hand hygiene

Ventilation of operative theatre

Clinical waste

Environmental cleaning and decontamination

Sterilisation of equipment

Question 13

What is decontamination?

Answer 13

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 14

What is disinfection?

Answer 14

Reduces micro-organisms to a level at which they are not harmful.

Question 15

What are the 2 main methods of disinfection?

Answer 15

1. Heat disinfection e.g. dishwasher, bed pan washer;

2. Chemical disinfection e.g. endoscope washer/disinfector, chlorine-releasing agent for cleaning equipment.

Question 16

What is cleaning?

Answer 16

The removal of dirt, dust or any organic matter using water and detergent.

About 80% of micro-organisms will also be removed if the item is dried, therefore drying is an important part of the process.

Question 17

What is sterilisation?

Answer 17

Sterilisation destroys all micro-organisms including spores.

Question 18

What methods of sterilisation are there?

Answer 18

1. Heat
   - Moist: autoclave: Delivery of steam under high pressure. Specific pressure and temperatures
   - Dry: oven: Controlled temperature cycles (i.e. 160oC for 2 hours or 170oC for 1hour)
2. Chemical: Gas, liquid
3. Filtration
4. Ionising radiation

Question 19

What is ionising radiation used to sterilise?

Answer 19

Used for single use disposable equipment

Question 20

What is the preferred method of sterilisation?

Answer 20

Heat by autoclave

Question 21

What factors determine the method of decontamination used?

Answer 21

Risk of infection (high, intermediate, low)

Physical properties: Item, Packaging materials

Decontamination level: Sterilisation, disinfection (antisepsis), cleaning, disposal

Question 22

Which method of decontamination is the least hazardous?

Answer 22

Heat is the least hazardous method and should be used where possible

Question 23

What is chemical disinfection is largely limited to?

Answer 23

Environmental decontamination (surfaces, spills etc.)
Antisepsis
Heat-sensitive items

Question 24

Which method is used to decontaminate items/devices that will enter sterile body areas or break the skin?

Answer 24

STERILISE

Question 25

Which method is used to decontaminate items/devices that will contact mucous membranes or that will be contaminated with body fluids?

Answer 25

DISINFECT

Question 26

Which method is used to decontaminate items/devices that only contact intact skin (no body fluids)?

Answer 26

CLEAN

Question 27

What is cleaning as a method of decontamination suitable for?

Answer 27

Any item that comes into contact with intact skin, e.g. beds chairs, non-invasive equipment e.g. monitoring equipment and intravenous pumps.

Cleaning is also an essential first step when decontaminating items by disinfection and sterilisation.

Question 28

What is antisepsis? What does it require?

Answer 28

Disinfection applied to damaged skin or living tissues. It requires a disinfectant with minimal toxicity.

Question 29

When is soap and water needed? When is alcohol gel suitable?

Answer 29

Soap & Water for visibly soiled hands and contact with particular infections e.g. C. difficile, viral gastro-enteritis.

Alcohol gel is suitable for most of the activities you are likely to undertake on visiting clinical areas.

Question 30

Example: surgical instrument reprocessing. (Physical properties: metal construction, paper/cloth packaging).

1) Risk of infection?
2) Decontamination level?
3) Decontamination method?

Answer 30

1) high
2) sterilisation
3) moist heat by autoclave

Question 31

Example: central venous catheter (CVC) insertion site. (Physical properties: living tissue).

1) Decontamination level?
2) Decontamination method?

Answer 31

1) disinfection (antisepsis as LIVING tissue)

2) chemical: 2% chlorhexidine in 70% isopropyl alcohol

Question 32

Example: surgeon’s hands.

1) Decontamination level?
2) Decontamination method?

Answer 32

1) washing/cleaning

2) surgical scrub

Question 33

What are fomites?

Answer 33

objects or materials which are likely to carry infection, such as clothes, utensils, and furniture.

Question 34

Where should MRSA positive patients be treated?

Answer 34

MRSA positive patients should be nursed in a single room with en suite toilet facilities

Question 35

When are the ‘5 moments for hand hygiene at the point of care’?

Answer 35

1. Before patient contact
2. Before aseptic task
3. After body fluid exposure risk
4. After patient contact
5. After contact with patient surroundings