Healthcare Acquired Infections Flashcards
What is a HAI?
- 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
Possible outcomes of a HAI?
- extended length of stay, pain, discomfort, permanent disability, death
- increased cost
- Litigation
- loss of public confidence and decreased staff morale
What are most common sites of HAI? What in the healthcare context can cause these?
>UTI: catheterisation > Surgical site infection >Respiratory tract infection: intubation >Blood stream infections: central venous catheters >GI infection >Skin and soft tissue infection
What is the fundamental question of clinical microbiology? How does it relate to HAI?
Colonisation vs infection?
We are all colonised by bugs but are rarely infected
Are people colonised by Staph Aureus?
Yes. Approx. 30% are colonised. Most are colonised with Meticillin Sensitive Staph Aureus (MSSA)
Colonised Staph Aureus can also cause infection how?
> Break in skin eg surgical site infection
Vascular device (eg PVC, CVC)
Catheter associated UTI
Ventilator associated pneumonia
What are microbial factors tipping balance towards infection?
Increased >resistance >virulence >transmissability >Inc survival ability >ability to evade host defences
What are host factors tipping balance towards infection?
>devices eg CVC, catheter, ventilation >antibiotics >break in skin surface >foreign body >immunosuppression >age extremes >overcrowding
What are the means of transmission? Give an example of an organism which you can be infected by for each transmission mode
> Direct: staph aureus
Respiratory: Neisseria meningitidis, mycobacterium tuberculosis
Faecal-oral: C Diff
Penetrating injury: Group A streptococcus
How can you ‘break the chain’ of infection? (Microbe source, transmission, host)
- risk awareness
- standard infection prevention and control precautions
- hand hygiene
- appropiate PPE
- vaccination
- post exposure prophylaxis
- environment
What is:
>cleaning
>disinfection
>sterilisation?
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
Name some instruments that come with low risk of HAI and how do we reduce this risk?
- Stethoscope
- cots
- mattresses
From intact skin contact. Reduce risk by cleaning
Name some instruments that come with medium risk of HAI and how do we reduce the risk?
- bedpans
- vaginal specula
- endoscopes
From mucous membrane contact. Reduce risk by disinfection or sterilisation as appropiate
Name some instruments that come with high risk of HAI and how do we reduce the risk?
-surgical instruments
Reduce risk by sterilisation
Discuss features of cleaning equipment
- use detergent of water
- drying is important part of process
- cleaning essential prior to disinfection and sterilisation
What are methods of disinfection?
Heat
>Pasteurisation (eg bedpans, linen, dishwashers)
>Boiling (eg vaginal specula, ear syringes)
Chemical
>eg alcohol, hydrogen peroxide
What are methods of sterilisation?
> steam under pressure
hot air oven
gas (ethylene dioxide)
ionising radiation
What different surveillance types exist for disinfection of equipment?
- Local
- National
Define an outbreak?
2 or more cases of an infection linked in time and place
How do you go about identifying outbreaks?
-have to act on suspicion
-typing methods (necessary to determine if same strain present):
>antibiogram
>phage typing
>pyocin typing
>serotyping
>molecular typing
What are control measures for outbreaks?
>Single room isolation >Case cohorting >Clinical ward closure >Re-inforcement of IPC measures >Staff exclusion >Staff colonisation
C. Diff infection clinical features?
- diarrhoea
- faeces have characteristic colour
- abdominal pain, pyrexia, raised WCC
- pseudomembranous colitis
Do toxin negative strains of C. Diff cause disease?
No
What does C. diff infection arise from?
Imbalance in gut flora, either endogenous or exogenous source. Underdiagnosed in community
