UTI, Chest, Soft Tissue

Question 1

UTI main 3 types: how to test?

Answer 1

1. Cystitis (lower, bladder):
   - Mid stream urine culture
   - Bag urine (children)
   - Suprapubic urine (children)
   - Catheter sample (beware positive culture doesn’t always = infection, could be colonization)
2. Pyelonephritis (kidney): same tests as above PLUS Blood culture – patient is usually febrile or septic (loss consciousness)
3. Catheter associated UTI (CAUTI):
   -Catheter sample
   Remember:
   ▪urine culture may be polymicrobial : positive
   culture doesn’t always = infection!
   ▪dipstix/UFEME results become unreliable

Question 2

5 commonest bacteria causing UTI

Answer 2

1. Escherichia coli (E coli): Commonest
2. Proteus: Associated with kidney stone – staghorn calculus
3. Enterobacter, Citrobacter, Morganella, Serratia
4. Klebsiella pneumonia
5. Pseudomonas aeruginosa Especially previous antibiotic exposure, presence of urinary catheter

Question 3

Management for 3 main types of UTI

Answer 3

1. Cystitis + Catheter associated UTI: If stable and well,
   * PO antibiotics
   * Short course (3-7 days)
   * Presence of catheter usually requires min. 5 days antibiotics
   * Men require longer course than women
2. Pyelonephritis:
   * Start with IV antibiotics
   * Followed by PO antibiotic if improving after 48 hours
   * Total antibiotic duration – 7 to 14 days depending on
   choice of antibiotic

Question 4

asymptomatic bacteruria amount?

Answer 4

10^5 CFU/ml (100,000 CFU/ml) bacteria in urine
culture but patient is asymptomatic
CFU=colony forming unit

Question 5

3 main definitions for PULMONARY INFECTIONS (chest)

Answer 5

• community acquired pneumonia (CAP)
• hospital acquired (nosocomial) pneumonia (HAP) – pneumonia which occurs 48 hours or
  more after hospital admission
• ventilator associated pneumonia (VAP) - pneumonia which occurs 48-72 hours
  after endotracheal intubation

Question 6

Expected pathogens for 3 types of pneumonia

Answer 6

1. CAP:
   - ‘typical bacteria’ – Streptococcus pneumoniae, Haemophilus influenzae
   - ‘atypical bacteria’ – Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella
   pneumophila
   - Others – Staphylococcus aureus (esp. post influenza), Klebsiella pneumoniae
   - Don’t forget about viruses - Influenza
2. HAP
   - Streptococcus pneumoniae, Haemophilus influenzae
   - ‘coliforms’: IMPT TABLE
   - Pseudomonas aeruginosa
   - Other gram negative bacilli - Acinetobacter
   - MRSA (if patient is MRSA positive or high prevalence)

3.VAP: Similar to HAP

Question 7

samples (1) and tests (2) for Pneumonia. MCS?

Answer 7

Sputum, Endotracheal aspirate (ETA), BAL (bronchio-alveolar lavage):
- Microscopy: Gram stain: Beware of sputum Gram stain report – if there is high count of epithelial cells, this indicates sample is poorly taken, result is unreliable
- Culture and sensitivity: For most bacteria
- PCR: This is for detection of viruses because viral culture is no performed
And ‘atypical bacteria’ in CAP

Question 8

4 important skin conditions + features + pathogens

Answer 8

1. Cellulitis,
   impetigo,
   folliculitis,
   furuncles,
   carbuncles:
   Cellulitis
   * usually red / hot /tender
   * involves subcutaneous tissues, hence more
   diffuse margin compared to Erysipelas
   Impetigo
   * (children), perioral, starts as vesicle –> ruptures
   releasing yellowish, thick, wet crust
   Pathogen: Staph aureus, Beta-haemolytic Strep (esp Group A Strep)
2. Fournier’s
   gangrene
   (Type 1
   necrotizing
   fasciitis):
   * More common than Type 2 NF
   * More indolent, better prognosis, easier
   * to recognise clinically than Type 2 NF
   * Affecting perineal, genital, perianal region
   * Mortality? Variable - depends on underlying
   * co-morbidities
   Pathogen: many
3. Type 2
   Necrotising
   facsciitis (NF):
   * Aggressive
   * Easily missed
   * Pain out of proportion with skin appearance
   * Mortality approx 30%, depends if associated
   with myositis or toxic shock
   Pathogen: Group A Strep is the classical bug, Staph aureus
4. Gas
   gangrene
   (myonecrosis):
   * Uncommon
   * Infection of muscle
   * Develops rapidly, life-threatening
   * Clostridial infection – typically after trauma
   (deep, penetrating injury – knife, gunshot, crush)
   * Following bowel surgery
   * Spontaneous! (esp those with colonic cancer)
   Pathogen: Clostridium perfringens

Question 9

Principles of swabbing skin:
find the ___instead of colonising flora
eg of prone to colonisations (4 wound types)?

Answer 9

find the causative agent (bacteria) instead of colonising flora
eg of prone to colonisations:
1. Open wound
2. VAC dressing wound
3. Pressure sore
4. Chronically broken skin areas eg diabetic foot wound