Clinical Microbiology

Question 1

Managing an outbreak (5 steps)

Answer 1

• Detection (trigger suspicion of outbreak)
• Laboratory investigation
• Epidemiological investigation
• Control measures
• Resolution

Question 2

Lab investigation - phenotypic methods

Answer 2

– Are they all the same species?
– Do they share the same antibiotic sensitivity pattern?
– Serotyping – eg O & H antigens in Salmonella
– Phage typing (susceptibility to lysis by different
bacteriophages)

Question 3

Lab investigation - genotypic methods

Answer 3

– Pulsed-field gel electrophoresis
– Ribotyping
– Multi-locus sequence typing
– Whole genome sequencing

Question 4

symptoms of pyelonephritis

Answer 4

*Flank pain
*Fever / Rigors
*Systemically unwell
*Bloodstream infection

Question 5

symptoms of cystitis

Answer 5

*Urinary frequency
*Urgency of urination
*Dysuria
*Lower abdominal pain
*White blood cells in
urine

Question 6

Sepsis Pathophysiology

Answer 6

• bacterial products and components
• activation of monocytes
• Release of
  inflammatory mediators
  eg. IL-1, TNFα
  ->
  BRAIN
• fever
• increased heart and respiratory rate

BLOOD VESSEL WALL
- ‘neutrophil margination’
- platelet adherence
- blood clot formation (hypoxia and damage to tissues in various systems)

VASCULAR ENDOTHELIUM
- vasodilation mediated by nitric oxide production
(hypoxia and damage to tissues in various systems)

Question 7

Key features of PCR

Answer 7

• Rapid (few hours)
• Very sensitive – can detect smaller amounts of
  pathogen that required for successful culture
• DNA persists even in damaged or dead
  pathogens – both a strength and a weakness!
• Only detects specific pathogens that you set
  out to detect – contrast with culture.