Healthcare Acquired Infections

Question 1

What are HAI?

Answer 1

Infections that were not present or in the pre-symptomatic phase at the time of admission to hospital

They arise > 48 hours after admission or within 48 hours of discharge

Disturbance in bacterial-host equilibrium leads to most HAI

Question 2

What are the outcomes of HAI?

Answer 2

Extended length of stay, pain, discomfort etc

Question 3

What are the common sites of HAI?

Answer 3

UTI- related to catheterisation
Surgical site infection
Respiratory tract infection (intubation)
Bloodstream infections
GI infection
Skin + soft tissue

Question 4

What are the body’s defence mechanisms?

Answer 4

1st line = physical barrier
intact skin, bacterial flora, body secretions, gastric acid, flushing (e.g. urination)

2nd line = immune system

Question 5

What is the difference between colonisation + infection?

Answer 5

Colonisation: germs are on the body but do not make you sick
Infection: microbes are in the body resulting in symptoms and signs

an example:
Staph A. are COLONISED in the nose of ~30% of population
Staph A can also cause INFECTION through break in the skin, vascular device, catheter, ventilator etc

Question 6

What are MICROBIAL factors tipping the balance of bacterial-host equilibrium towards infection?

Answer 6

Increased microbial

• resistance
• virulence
• transmissibility
• ability to evade host defences

Question 7

What are HOST factors tipping the balance of bacterial-host equilibrium towards infection?

Answer 7

Devices: catheter, ventilation
Antibiotics
Break in skin
Foreign body
Immunosuppression
Age extremes
Increased opportunity for transmission e.g. hands, mobile phones

Question 8

What is the chain infection?

Answer 8

The source of microbe, transmission, host

This information is needed to prevent or interrupt an epidemic

Question 9

How do you break the chain of infection?

Answer 9

Risk of awareness, standard infection prevention, hand hygiene, vaccination, post exposure prophylaxis, environment

Question 10

What are the means of transmission?

Answer 10

Direct contact, respiratory/ droplet, faecal-oral, penetrating injury

Question 11

What is the definition of cleaning?

Answer 11

Physical removal of organic material and decrease in microbial load

Question 12

What is the definition of disinfection?

Answer 12

Large reduction in microbe numbers, spores may remain

Question 13

What is the definition of sterilisation?

Answer 13

Removal/ destruction of ALL microbes and spores

Question 14

What cleaning/ disinfection/ sterilisation method is appropriate for low, medium and high risk objects?

Answer 14

Low risk = clean with manufacturer’s instructions
e.g. stethoscopes, cots

Medium risk = disinfect or sterilisation as appropriate
e.g. bedpans, vaginal speculum

High risk = sterilisation
e.g. surgical instruments

Question 15

What methods of disinfection are there?

Answer 15

Heat
Chemical (vary in their organism activity range)

Question 16

What methods of sterilisation are there?

Answer 16

Steam under pressure
Hot air oven
Gas
Ionising radiation

Question 17

What surveillance of HAI is there

Answer 17

Local surveillance- lab based (notifies clinicians)

National surveillance - for MRSA, C. diff, E. Coli bacteraemia, Surgical site infection etc

Question 18

What is an outbreak?

Answer 18

2 or more cases of an infection linked in time and place

Question 19

What is the purpose of the infection prevention and control team?

Answer 19

To prevent individual infections and outbreaks

Question 20

What is the purpose of surveillance?

Answer 20

To detect and identify a possible outbreak at the earliest opportunity

Question 21

What is necessary of there is an outbreak?

Answer 21

Typing of bacteria

Control measures- isolation, cohort cases, ward closure, re-enforcement of IPC measures, staff decolonisation

Question 22

What are the characteristics of a Clostridium Difficile infection?

Answer 22

Diarrhoea
Abdominal pain
Pyrexia
Raised WCC
Pseudomembranous colitis

Question 23

Why does a positive toxin test of C. diff not always mean infection?

Answer 23

Because diarrhoea symptoms needs to be present
It is part of normal gut flora in ~2% of people
(Toxin negative strains do not cause disease)

Question 24

What is the treatment for C. diff?

Answer 24

Stop antibiotics predisposing to it if possible
Give oral metronidazole
Oral vancomycin if severe
Do not treat symptom free