Microbiology A3 - Controlling Infection Flashcards
Endogenous and Exogenous Infection Sources
Endogenous Infection
What is it? What pathogens are involved? Give 3 examples.
Endogenous Infection
- Infection under specific conditions by the normal flora.
- This makes them opportunistic pathogens.
Examples: aspiration pneumonia; neutropenic sepsis; cannulation.
Endogenous and Exogenous Infection Sources
Exogenous Infection
What is it? Give 3 examples.
Exogenous Infection
- Organism acquired from a non-host origin
Examples:
-Legionella with infected water supply and aerosol transmission.
- Clostridium which can proliferate in the gut during antibiotic therapy.
- Salmonella from unclean food and polluted water.
Hospital Acquired Infection
Define.
Definition: An infection that was not present or incubating at the time of hospital admission.
Hospital Acquired Infection
What 4 factors increase the likelihood of a hospital giving a patient an infection?
- Air Conditioning and piped air supplies: Legionella)
- Fomites (light boxes, door handles, bed sheets, etc) that have been used or handled by someone with a communicable disease and thereby contaminated.
- Hospital food can transmit infection through inadequate temperature and issues transporting it to the wards.
- Water supplies can be a source of Legionella, especially if pipework is lukewarm.
Hospital Acquired Infection
Patient-centred Factors
- Restricted ability to access washing facilities.
- Effects of disease or treatment lowering resistances (e.g. antibiotics and C. difficile).
- Effects of close patient contact in a busy ED (e.g. allowing easier spread of airborne pathogens such as A/H1N1 influenza).
Hospital Acquired Infection
Cannulation
- Commonest cause of hospital-acquired bacteraemia.
- Infection risk is a direct effect of length of time in situ
- Current guidance states cannulae should not remain in place for greater than 48 hours).
- Typical organisms are skin commensals such as S. aureus and S. epidermidis.
Hospital Acquired Infection
Urinary Catheters
- Can act as a source of ascending infection.
- Urinary stasis relating to a blocked catheter is a risk factor for colonisation and subsequent infection.
Hospital Acquired Infection
Staff Clothing
- The ‘bare below the elbow’ approach is important.
- This reduces the risk of staff clothing acting as a fomite.
Hospital Acquired Infection
Methods of Control of Hospital Acquired Infections (4)
- Handwashing
- Isolation of patients using aprons, gloves, alcohol gel and separate sinks
- Disinfection
- Sterilisation: The inactivation of all infectious agents, usually by irradiation or autoclaving.
How are influenza and neisseria meningitidis spread?
Droplet
How is salmonella spread?
Faecal-oral
How is Leptospira spread?
Invasion of intact skin
How is Staph epidermidis spread?
Invasion of breached skin
How are HIV and Gonorrhoeae spread?
Sexual intercourse
What does disinfection do?
Reduces the number of infectious particles
