Tag Archives: infectious disease

MRI evolution of Cerebral Abscess




Criner, G., Barnette, R. and D’Alonzo, G. (2010). Critical Care Study Guide. Dordrecht: Springer.




Empiric treatment of selected infections in the NICU





O’Horo, J. and Sampathkumar, P. (2017). Infections in Neurocritical Care. Neurocritical Care.

Treatment of Native Vertebral Osteomyelitis (IDSA, 2015)

Parenteral Antimicrobial Treatment of Common Microorganisms Causing Native Vertebral Osteomyelitis



Berbari, Elie F. et al. “2015 Infectious Diseases Society Of America (IDSA) Clinical Practice Guidelines For The Diagnosis And Treatment Of Native Vertebral Osteomyelitis In Adults”. Clinical Infectious Diseases 61.6 (2015): e26-e46. <PDF link>


Antibiogram (LHH-Year 2015)




LHH Antibiogram

Empiric Antibiotics for Brain Abscess

Base empiric therapy on presumed source of abscess and Gram stain results

Source: mouth, ear, sinus

  • [Penicillin (mouth) OR cefotaxime (ear/sinus)] + [metronidazole]

Source:  neurosurgery / post-op

  • [ceftazidime OR cefepime OR meropenem OR imipenem] + [vancomycin]

Source: penetrating trauma

  • [ceftriaxone or cefotaxime] + [vancomycin] +/- [metronidazole  (sinus involvement)]

Source:  hematogenous spread (IE, multiple abscess)

  • [ceftriaxone or cefotaxime] + [vancomycin] + [metronidazole]

Source: unknown

  • [ceftriaxone or cefotaxime] + [vancomycin] + [metronidazole]



  • Cefepime 2g IV q8h
  • Cefotaxime 2g IV q4-6h
  • Ceftriaxone 2g IV q12h
  • Ceftazidime 2g IV q8h
  • Imipenem 500-1000mg q6h
  • Meropenem 2g IV q8h
  • Metronidazole 15mg/kg IV load then 7.5mg/kg IV q8h;  usually 1G load & 500mg q8h
  • Nafcililn 2g IV q4h
  • Oxacillin 2g IV q4h
  • Penicillin G 20-24 M units / day IV in 6 divided doses
  • Vancomycin 15-20mg/Kg IV q8-12h



Uptodate: Treatment and prognosis of bacterial brain abscess, accessed 01/10/2017.


Penicillin Allergy and Cephalosporins

What to do when patients say they are PCN allergic?

  • determine whether an IgE-mediated response (i.e. anaphylaxis) occurred
    • If so
      • third- and fourth-generation cephalosporins can be used generously
      • first- and second-generation cephalosporins with R1 side chains similar to PCN should be avoided (see table below)
      • first- and second-generation cephalosporins with different R1 side chains can be given (see table below)
  • Skin testing not recommended for determining safety of administering cephalosporins to PCN-allergic patients (because it is unreliable)
    • Skin testing does predict true PCN allergy



Penicillin and cephalosporins known to have a risk of allergic cross reaction:Capture.JPG

Patients who are allergic to amoxicillin or ampicillin should avoid the cephalosporins listed, because they have similar R1-group side chains.


Myth: ~10% of patients with history of PCN allergy will have an allergic reaction if given cephalosporin.

True: Overall cross-reactivity rate is ~1% when using first gen cephalosporins or cephalosporins with similar R1 chains.  PCN-allergic patients, use of 3rd or 4th generation cephalosporins carries a negligible risk of cross allergy.



Campagna, James D. et al. “The Use Of Cephalosporins In Penicillin-Allergic Patients: A Literature Review”. The Journal of Emergency Medicine 42.5 (2012): 612-620.

Intracranial Fluid Compartments

Here is a very useful schematic illustration of the intracranial fluid compartments, which may help visualize some concepts in CNS drug delivery.


  • Arrows = direction of CSF flow
  • Broken arrows = where diffusion may occur between brain, blood vessels, CSF, tissue
    • (a) across BBB
    • (b) across choroid plexus
    • (c) across ependyma
    • (d) across pia-glial membranes (brain or spinal cord surface)
    • (e and f) across cell membranes of neurons and glial cells



Nau, R., F. Sorgel, and H. Eiffert. “Penetration Of Drugs Through The Blood-Cerebrospinal Fluid/Blood-Brain Barrier For Treatment Of Central Nervous System Infections”. Clinical Microbiology Reviews 23.4 (2010): 858-883.