Question 1

College answer

Not available.

Discussion

More explanation for the specific choice of investigations and antibiotics is available in the staphylococcal bacteremia chapter. Unfortunately, all efforts to produce a concise answer (one which could be written in the space of ten minutes) have failed, yielding to the irresistible completionist urge, and producing a "model answer" that is comprehensive and impossible. 

• Assessment:
  • History looking for specific aetiological clues, as well as risk factors for complicated S.aureus bacteraemia or IE:
    • IV drug use
    • Immune compromise
    • Intravascular devices, prostheses or implants
    • Existing valvular disease
    •  
  • Physical examination:
    • A skin check, looking for:
      • Cellulitis and broken skin (ulcers, etc)
      • Signs of disseminated disease, eg. the peripheral stigmata of IE
    • Intravascular device assessment, focusing on:
      • the condition of the insertion site
      • the age of the line
      • the need for the line
    • Cardiovascular/respiratory examination, looking for:
      • New murmurs
      • New heart failure
      • Features of pneumonia
    • Neurological examination, looking for:
      • New focal neurodeficit (embolic CNS disease)
      • Peripheral neurodeficit suggestive of epidural abscess
    • Musculoskeletal examination, looking for:
      • Joint effusions
      • Myositis/fasciitis
      • Osteomyelitis/discitis
  • Bloods and biochemistry:
    • LFTs, to (also, to assess the effect the flucloxacillin is having on the liver)
    • EUC/CMP to establish baseline renal function and to detect any glomerulonephritis
    • Inflammatory markers (though some might say that with the bacteremia, you've identified that there is an infection, and you are committed to a long course of IV antibiotics, so what role could procalcitonin or CRP possibly play?)
  • Imaging studies:
    • Echocardiography, looking for IE
    • CT chest/abdomen/pelvis/brain with IV contrast, looking for metastatic foci of infection and septic emboli
    • MRI spine, looking for discitis osteomyelitis and epidural abscess
  • Microbiology investigations:
    • Repeat sets of blood cultures (ideally, repeated daily or second-daily until the bacteraemia is cleared)
    • Specific site sampling, including potentially:
      • Wound swabs
      • Line tip cultures
      • Abscess aspirates
      • Joint aspirates
      • Tissue cultures (eg. from valves)
• Management:
  • Infectious diseases referral (reduces mortality!)
  • Antibiotic options:
    • ETG recommend flucloxacillin or cephazolin
    • For patients who are allergic to β-lactams,  desensitization therapy should be attempted, because the β-lactams are a clearly superior choice, and should be used wherever possible (instead of just resorting to vancomycin).  
  • Source control:
    • If at all possible, the source of the bacteremia needs to be removed. 
    • This may require:
      • Removal of suspected intravascular devices
      • Washout of infected joints
      • Explantation of infected prostheses
      • Valve replacement
  • Control potential sources:
    • It may actually be worthwhile removing all long-term intravascular devices (eg. PICC lines), waiting until the bacteraemia has resolved, and then resiting them after 2-3 blood cultures have returned negative results.