Tag Archives: infectious disease

MRI evolution of Cerebral Abscess

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Reference:

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

 

 

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Empiric treatment of selected infections in the NICU

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Reference:

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

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Reference:

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)

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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]

 

Dosages:

  • 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

 

Reference:

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

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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.

 

Reference:

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.

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  • 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

 

Reference:

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.