Healthcare Acquired Infections

Question 1

What is a HAI?

Answer 1

• infections that were not present or in the pre-symptomatic phase at time of admission
• which arise at least 48h after admission or within 48h of discharge

Question 2

Possible outcomes of a HAI?

Answer 2

• extended length of stay, pain, discomfort, permanent disability, death
• increased cost
• Litigation
• loss of public confidence and decreased staff morale

Question 3

What are most common sites of HAI? What in the healthcare context can cause these?

Answer 3

>UTI: catheterisation
> Surgical site infection
>Respiratory tract infection: intubation
>Blood stream infections: central venous catheters
>GI infection
>Skin and soft tissue infection

Question 4

What is the fundamental question of clinical microbiology? How does it relate to HAI?

Answer 4

Colonisation vs infection?

We are all colonised by bugs but are rarely infected

Question 5

Are people colonised by Staph Aureus?

Answer 5

Yes. Approx. 30% are colonised. Most are colonised with Meticillin Sensitive Staph Aureus (MSSA)

Question 6

Colonised Staph Aureus can also cause infection how?

Answer 6

> Break in skin eg surgical site infection
Vascular device (eg PVC, CVC)
Catheter associated UTI
Ventilator associated pneumonia

Question 7

What are microbial factors tipping balance towards infection?

Answer 7

Increased
>resistance
>virulence
>transmissability
>Inc survival ability
>ability to evade host defences

Question 8

What are host factors tipping balance towards infection?

Answer 8

>devices eg CVC, catheter, ventilation
>antibiotics
>break in skin surface
>foreign body
>immunosuppression
>age extremes
>overcrowding

Question 9

What are the means of transmission? Give an example of an organism which you can be infected by for each transmission mode

Answer 9

> Direct: staph aureus
Respiratory: Neisseria meningitidis, mycobacterium tuberculosis
Faecal-oral: C Diff
Penetrating injury: Group A streptococcus

Question 10

How can you ‘break the chain’ of infection? (Microbe source, transmission, host)

Answer 10

• risk awareness
• standard infection prevention and control precautions
• hand hygiene
• appropiate PPE
• vaccination
• post exposure prophylaxis
• environment

Question 11

What is:
>cleaning
>disinfection
>sterilisation?

Answer 11

Cleaning - physical removl of organic material and decrease in microbial load

Disinfection - large reduction in microbe numbers - spores may remain

Sterilisation - removal/destruction of ALL microbes and spores

Question 12

Name some instruments that come with low risk of HAI and how do we reduce this risk?

Answer 12

• Stethoscope
• cots
• mattresses

From intact skin contact. Reduce risk by cleaning

Question 13

Name some instruments that come with medium risk of HAI and how do we reduce the risk?

Answer 13

• bedpans
• vaginal specula
• endoscopes

From mucous membrane contact. Reduce risk by disinfection or sterilisation as appropiate

Question 14

Name some instruments that come with high risk of HAI and how do we reduce the risk?

Answer 14

-surgical instruments

Reduce risk by sterilisation

Question 15

Discuss features of cleaning equipment

Answer 15

• use detergent of water
• drying is important part of process
• cleaning essential prior to disinfection and sterilisation

Question 16

What are methods of disinfection?

Answer 16

Heat
>Pasteurisation (eg bedpans, linen, dishwashers)
>Boiling (eg vaginal specula, ear syringes)

Chemical
>eg alcohol, hydrogen peroxide

Question 17

What are methods of sterilisation?

Answer 17

> steam under pressure
hot air oven
gas (ethylene dioxide)
ionising radiation

Question 18

What different surveillance types exist for disinfection of equipment?

Answer 18

• Local

- National

Question 19

Define an outbreak?

Answer 19

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

Question 20

How do you go about identifying outbreaks?

Answer 20

-have to act on suspicion
-typing methods (necessary to determine if same strain present):
>antibiogram
>phage typing
>pyocin typing
>serotyping
>molecular typing

Question 21

What are control measures for outbreaks?

Answer 21

>Single room isolation
>Case cohorting
>Clinical ward closure
>Re-inforcement of IPC measures
>Staff exclusion
>Staff colonisation

Question 22

C. Diff infection clinical features?

Answer 22

• diarrhoea
• faeces have characteristic colour
• abdominal pain, pyrexia, raised WCC
• pseudomembranous colitis

Question 23

Do toxin negative strains of C. Diff cause disease?

Answer 23

No

Question 24

What does C. diff infection arise from?

Answer 24

Imbalance in gut flora, either endogenous or exogenous source. Underdiagnosed in community

Question 25

How is C. Diff infection diagnosed?

Answer 25

Positive toxin test AND diarrhoeal symptoms

Question 26

Why is C. Diff infection still occurring?

Answer 26

• cant prevent all cases
• antibiotics can predispose to CDI
• new strains?
• environmental contamination may be issue
• Inc number of vulnerable patients close together

Question 27

Treatment of C. diff infection?

Answer 27

-stop predisposing antibiotics
-if symptomatic, give:
>oral metronidazole
>oral vancomycin if severe
>oral fidaxomycin if 2nd episode
-dont treat if symptom free, can cause CDI

Question 28

What are the 4C’s in reducing CDI?

Answer 28

• cephalosporin
• co-amoxiclav
• clarithromycin
• ciprofloxacin