Case 3: Healthcare Acquired Infection Flashcards
What are healthcare acquired infections?
Infections that patients get while receiving treatment (from devices used in procedures like catheters and ventilators) for medical or surgical conditions.
What are some common HAIs?
○ Catheter-associated urinary tract infections (e.g. leaving the catheter in for too long like in Mr Ratchett’s case)
○ Surgical site infections (can be superficial or under the skin wounds)
○ Bloodstream infections
○ Ventilator- associated Pneumonia (if germs enter through the ventilator tube and get into the patient’s lungs, infection can arise)
○ Clostridium difficile (side effects of antibiotics)
What is the chain of infection (sequence of events that leads to infection) ?
- Infectious agent
- Reservoir (the habitat in which the pathogenic agent usually lives and proliferates)
- Portal of exit (how the pathogen leaves its host)
- Mode of transmission
- Portal of entry (the manner in which a pathogen enters a susceptible host)
- Susceptible host
What is the impact of HAIs on the NHS and its workers?
- More resources are used up (e.g. beds)
- Increase in antibiotic resistance: more expensive
- If the disease spreads to the workers, it can mean time off work, which costs the NHS.
What is the impact of HAIs on patients?
- It can be harmful for their mental health as they have to be isolated.
- Longer stay which can be harmful physically.
- Financially harmful as they have to take time off work
- They may lose trust in health-care professionals
- Greater morbidity and mortality
- Patients may have surgical failure as wounds may fail to heal
What are the modes of transmission?
- Direct (contact or droplet)
- Indirect (airborne dust, vectors, vehicles like blood, food and water, fomites like catheters)
When should you wash your hands?
1) Before touching a patient
2) Before asceptic procedures
3) After bodily fluid exposure risk
4) After touching patient/their charts
5) After touching patient’s surroundings
Why should you wash your hands after a procedure even though you wore gloves during it?
Gloves don’t provide 100% protection and your hands will become contaminated while taking the gloves off.
How does the antibiotic sensitivity test work?
- A bacterial lawn is grown on a nutrient media plate.
- Discs covered with different antibiotics are placed in the plate.
- The plate is then incubated for 24 hours.
- Discs with zones of inhibition around them suggest that the bacteria is sensitive to those antibiotics. If some discs do not have any clear zones, the bacteria is resistant to those antibiotics.
What are some molecular mechanisms of resistance?
- Target site of antibiotic may be altered (the protein may change due to mutations so antibiotic can no longer bind to it)
- Antibiotic may become inactivated (enzymes may degrade the antibiotics like beta-lactamases)
- Bacteria may switch to alternative metabolic pathways or produce a protein that can outcompete the antibiotic.
- Bacteria may produce efflux pumps that pump the antibiotics out.
How do beta-lactams like penicillin and amoxicillin work?
Beta lactams prevent the synthesis of peptidoglycan cell walls in Gram + bacteria.
- They do this by binding to the active serine residues on the enzymes that make cross-linkages between the polysaccharides (penicillin-binding proteins).
- When they bind to the enzymes, they inhibit the enzyme and prevent the cross-linkage formation.
How can some bacteria be resistant to Amoxicillin but sensitive to Co-Amoxiclav (an antibiotic that contains amoxicillin)?
Some bacteria may produce enzymes like beta-lactamases that break down the biologically active lactam rings in beta-lactams like amoxicillin.
In Co-amoxiclav, Clavulanic acid binds to these beta-lactamases and prevent them from breaking down the amoxicillin.
Co-Amoxiclav is a broad-spectrum antibiotic. What are the risks associated with using this drug?
- As it is a broad-spectrum antibiotic, it can kill the good bacteria living in the gut flora.
- This means that opportunistic bacteria like C. difficile, that were previously being suppressed by the microbiome, can become active and toxigenic.
- C. difficile (another HAI) can cause diarrhoea and gut inflammation.
Mr Ratchett had to stay in hospital after his operation because he was suffering from post-operative urinary retention. What may have caused this?
- Usage of opioids and anaesthesia
- Existing prostrate problems
- Co-morbidites
- Constipation
How could post-operative urinary retention (and thus the catheterisation in the first place) be avoided?
Prevent constipation by..
- keeping the patient hydrated
- or giving the patient laxatives to open up bowel movements.
