What is a hospital-acquired infection (HAI)?
An infection developed in hospital which was not present or incubating at the time of admission
What % of patients do admitted to hospital HAIs occur in?
~25%
What are the most common sites of HAIs?
- Urinary tract
- Surgical wounds
- GI tract
- Any septicaemia
How severe are HAIs?
Range, from mild to life-threatening
Why do HAIs develop?
- Environment
- The host susceptible to infections
- Medical activites
- Change in microbiota of environment from the selection pressures of the hospital
What aspects of the hospital environment can cause HAIs?
- Food supply
- Air supply
- Fomites
- Water supply
What medical activities can cause HAIs?
- IV access
- Catheters
- Surgery
Why may patients be more susceptible to infection?
- Increasing age
- Co-morbidities
- Chronic illness
- Poor physical states
- Neutropenia from chemotherapy
- T cell deficiencies
Why may a patient have a T cell deficiency?
- HIV
- Transplant
Are HAIs exogenous or endogenous?
Can be either
What are endogenous microbiota?
The organisms that are part of the normal body microbiota, on the skin, GI tract etc.
What are exogenous microbiota with respect to HAIs?
Microbes transferred from the hospital to the patient, by direct contact of;
- Contaminated hands
- Clothing
- Medical devices
- Airborne spread
- Contaminated food, water, or medicines
What can exogenous microbiota be considered to be part of, with respect to HAIs?
The ecosystem of the hospital
How can endogenously acquired HAIs be minimalised?
- By effective disinfection of the skin prior to surgery, especially in the heavily bacterial contaminated parts of the body.
- Appropriate use of perioperative antibiotics prophylaxis protocol.
- Smoking cessation and good nutrition.
- Any sutures or drains should be changed regularly
How can operations be classified?
- Clean
- Contaminated
- Infected
What does the classification of an operation as clean, contaminated, or infected depend on?
The area involved
What does appropriate use of perioperative antibiotics prophylaxis protocal ensure?
That the antibiotic concentrations are highest at the surgical sites at maximal concentrations
What can prolonged administration of antibiotics cause?
Increased risk of infection by resistant organisms
How are exogenously acquired infections prevented?
Good clinical practice
What methods are effective in preventing exogenously acquired infections?
- Hand-washing
- Alcohol gel hand rubs
- Sterile gloves
Amongst who should good clinical practice with respect to preventing infection be encouraged?
Visitors
How can the number of antibiotic resistant organisms be reduced?
- Environmental cleaning
- Judicious antibiotic prescribing
How should the environment be cleaned to prevent antibiotic resistance?
- Sterilisation
- Disinfection
- Waste disposal
What should happen to any individuals harbouring resistant organisms?
They should be isolated in single rooms
What should happen to any individuals with air transmitted diseases?
They should be placed in a room with negative air pressure
How should instruments be used to prevent exogenous infection?
Should be single use where applicable, yet any recycled should be sterilised correctly
What should always be worn by healthcare workers to prevent exogenous infection?
Disposable gowns, gloves, and aprons
What do poor standards of care predispose to?
Higher rates of infection
What is meant by the endemic rate?
The normal rate of infection for a particular disease
What is an epidemic?
A significant increase in the rate of infection above the endemic level
What is an outbreak?
An epidemic due to a single cause
How can investigation of an infection source, especially in an outbreak, be aided?
Typing
What is the purpose of typing in infection investigation?
It determines if two organisms are identical or if there are differences between the two strains
What can typing be used to do?
Identify any difference, cannot claim isolates are identical
Give an example of where typing could be used in infection investigation
Could be used to identify that a surgical wound infection isolates are indistinguishable from an operating theatre washing basin, hence identify where the infection originated
What are the main typing techniques?
- Simple lab typing
- Serological testing
- Molecular typing
What is looked at in simple lab typing?
Appearance on agar
What does molecular typing use?
Restriction endonucleases
What happens in molecular typing?
Restriction endonucleases digest plasmid DNA or ribosomal RNA from the pathogen and check for the binding patterns produced
How is molecular typing interpreted?
Any identical bacteria will produce similar banding patterns