Lecture 40: Hospital acquired infections

Question 1

What can happen in systemic infection to a pts BP?

Answer 1

BP can drop due to shock

Question 2

What are the potential surgical sites of infection in a bowel resection?

Answer 2

1. The incision site of the skin
2. The resection itself

Question 3

What are some hospital acquired infections?

Answer 3

1. Pneumonia (from bed rest)
2. Urinary catheter
3. IV line infection (direct to blood)

Question 4

Write some notes on hospital acquired urinary infections?

Answer 4

• Dont usually cause people to be very sick (esp. since catheter voids the bladder keeping it empty and assisting washout)
• Would not have dysuria b/c of cather bipassing this
• Cather is irritating to urethra and can cause pyuria w/o infection

Question 5

Write some notes about CA-UTI:

Answer 5

Cather associated UTI

• Bacteria in urine (3x chance of death)
• ~10% of pts with catheters get CA UTI. Around 20% of people with catheters dont need them…
• Risk factors: Women, duration of catheterisation, poor care

Occasionally turns to polynephritis

Question 6

How would you recognise a CA-UTI?

Answer 6

• Specific symptoms might be lacking (catheter)
  = Fever, confusion, lethargy, flank pain
• Presence of pyuria is not diagnostic because can be caused by catheter (Although absence suggests other diagnosis)
• Smelly/cloudy urine is not diagnostic.

Cultures usually show one bacteria species i.e E.coli and other GNB i.e psuedomonas aeruginosa

Question 7

What strategies might reduce CA-UTI?

Answer 7

YES: Avoid, insert using aseptic technique, remove, appropriate care, condom catheters

NO: Antibiotic prophylaxis, antibiotics in urine bag, catheter irrigation, regular testing

Question 8

What can candida albicans cause?

Answer 8

• Nappy rash
• Thrush
• Candidaemia (hospital, IV devices, antibiotic use, very sick)
• Candiduria (urinary catheter, very rare, represents colonisation)

Question 9

What should happen once candiduria is identfied?

Answer 9

• remove catheter
• examine urine for WBC / signs of inflammation
• Check bloods for candidaemia
• Treat once this is done

Question 10

What is a biofilm?

Answer 10

Microbial community of cells that attach to a substrate or interface of to each other, embedded in a matrix of extracellular polymeric substance

Question 11

What are small colony variants?

Answer 11

• Colonies with reduced metabolic activity, can be dormant, increased antibiotic resistance (Persister cells)

Question 12

What are the three factors that determine pathogenesis of device associated infections?

Answer 12

• Bacteria
• Host
• Device

Question 13

What are device factors that favor bacterial adhesion?

Answer 13

1. Material (PVC>Titanium>silicon)
2. Source of material (synthetic>biomaterial)
3. Surface of device (Textured>smooth, irregular>regular)
4. Shape of device (polymeric tubing>wire mesh)

Question 14

What are the bacterial factors that promote device related infections?

Answer 14

• Non-specific (hydrophoboc, electrostatic)
• MSCRAMMS
• Polysacc intracellular adhesions

Question 15

What are the most common bacteria of device related infections?

Answer 15

Gram +ive (50-60% events):
S. epidermidis
S. aureus
Gram -ive: (~30% events)
E. coli

Fungi: Candida

(associated with biofilms)

Question 16

Whats the problems with biofilm assocaited bacteria?

Answer 16

• Harder to reach bacteria in biofilm
• Changed phenotype/gene expression
• Changed cell surface properties (resistance)
• Slower growth rate (resistance)
• PERSISTER CELLS
• Blood tests can be negative for bacteraemia after antibiotic treatment but biofilm might be present

Question 17

How can device associated infection be prevented?

Answer 17

• Reconsider requirement for the device
• Remove unnecessary devices
• Handwashing before and after touching devices
• Aseptic techniques
• Monitor closely for infection