T3-L11: Infection Prevention and Control

Question 1

Deine antisepsis.

Answer 1

Antisepsis relates to the removal, or elimination, of transient microorganisms from the skin and a reduction in the resident flora. It requires a disinfectant with a minimal toxicity.

Question 2

Define decontamination.

Answer 2

Decontamination: 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. There are various decontamination methods available appropriate for different situations.

Question 3

Define sterilisation.

Answer 3

Sterilisation destroys all micro-organisms including spores.

Question 4

Define disinfection.

Answer 4

Disinfection reduces micro-organisms to a level at which they are not harmful (does not completely remove them). The two main methods are:
• Heat disinfection e.g. dishwasher, bed pan washer;
• Chemical disinfection e.g. endoscope washer/disinfect, chlorine-releasing agent for cleaning equipment.
• Anti-sepsis - disinfection applied to damage skin or living tissues. Ot requires a disinfectant with a minimal toxicity.

Question 5

Describe the chain of infection of MRSA. (hint: There are 6 stages)

Answer 5

Pathogen: MRSA

Reservoir: Humans kin and particularly the nose and other moist and hairy areas. At any one time 30% of the population are colonised by Staph. Aureus

Exit

Transmission/Entry: Direct site with infected sites or indirect contract with fomites or hands of healthcare workers

Susceptible Host: Any patient with breakdown in skin integrity

Question 6

What are the roles of IPC in the chain of infection?

Answer 6

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

Question 7

What is an outbreak?

Answer 7

A situation that meets one of the following criteria:

* Two or more linked cases of the same illness
* When the observed number of cases exceeds the expected number e.g. 9 cases of MRSA in a 6 month period 
* Single case of disease caused by a significant pathogen (i.e. viral hemorrhagic fever - Ebola)

Question 8

Which organisms commonly cause outbreaks in hospitals?

Answer 8

Viruses:
	• Influenza
	• Norovirus
	• SARS CoV-2
Bacteria:
	• Clostridium difficile 
	• MRSA
	• Group A Streptococcus
	• VRE (vancomycin resistant Enterococci)
	• Multi drug resistant gram negatives ( ESBL, CPEs)
Fungi:
	•Aspergillus

Question 9

What is cleaning?

Answer 9

Cleaning is the removal of dirt, dust or any organic matter using water and detergent. Regardless of the decontamination method used, cleaning needs to happen first.

Question 10

What are methods of sterilisation?

Answer 10

Heat
• Moist: autoclave - this is the preferred method
○ 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)
• Chemical - Gas, liquid
• Filtration
• Ionising radiation - Used for single use disposable equipment

Question 11

Which method of sterilisation should be used in most cases?

Answer 11

Heat as it is the least hazardous - Chemical disinfection is largely limited to environmental contamination, antisepsis and heat-sensitive items.

Question 12

Which method do we use for:

(a) Items/devices that will enter sterile body areas or break the skin e.g. surgical instruments
(b) Items/devices that will contact mucous membranes or that will be contaminated with body fluids e.g. catheters
(c) Items/devices that only contact intact skin (no body fluids) e.g. surgeons hand

Answer 12

(a) Sterilisation - mostly by heat (by autoclave)
(c) Disinfectant (antisepsis) - chemical antisepsis in living tissue with minimal toxicity
(c) Cleaning

Question 13

What are the two classes of bacteria carry on our hands?

Answer 13

• Resident bacteria: These are deep seated and difficult to remove. They re only removed when undertaking a surgical or aseptic procedure.
• Transient bacteria: These are easily picked up and transferred. They are easily removed. They are an important cause of Healthcare associated infections - this is what we target when washing hands.

Question 14

At what point should we wash our hands at the point of care?

Answer 14

1. Before patient Contact
   
   2. Before a Septic Task
   3. After Body Fluid Exposure Risk
   4. After Patient Contact
   5. After Contact with Patient surroundings

Question 15

What IPC methods are used preoperatively?

Answer 15

All elective patients are screened for MRSA. Patients are swabbed in the nose, axilla and groin. For those who are positive are offered decolonisation using a topical antibiotic such as mupirocin or neomycin or a chlorhexidine body wash.

Question 16

What IPC methods are used perioperatively?

Answer 16

• Perioperative antibiotics - with activity against MRSA if known positive. Particularly in orthopedic surgery.
  
  • Surgical skin prep
  • Scrub technique and hand hygiene
  • Ventilation of operative theatre to prevent contaminated air entering the surgical field,
  • Clinical waste
  • Environmental cleaning and decontamination
  • Sterilization of equipment

Question 17

What IPC methods are used postoperatively?

Answer 17

• Wound care
  
  • Hand hygiene
  • Personal protective equipment - e.g. Aprons and Gloves
  • Patient placement - MRSA positive patients should be nursed in a single room with en-suite toilet facilities - they would only leave if necessary
  • Clinical waste - disposed of properly and not come into contact with anything else on the ward
  • Decontamination of medical equipment - most are single use or assigned to a patient - Stethoscopes, blood pressure monitors, USS probes etc.
  • Environmental cleaning and decontamination
  • Laundry