Question 26

You are called to urgently assess a one-month old infant who has been brought into the Emergency Department with a one-day history of fever and irritability progressing to an altered level of consciousness.

She is febrile (38.9ºC), responds only to pain and has a tense anterior fontanelle.

  1. List three diagnoses in addition to CNS infection that need to be considered. (30% marks)
  1. Provide your empiric antimicrobial regimen and discuss your rationale.      (60% marks)

The results of a lumbar puncture are shown below:


Patient Value

Adult Normal Range


1.4 mmol/L*

2.8 – 4.4


3.36 g/L*

0.1 – 0.7

Red Cell count

5 cells/high power field

0 – 5

White Cell Count

3220 cells/high power field*

0 – 5







Gram Stain

Occasional Gram-positive bacilli seen

  1. What is the likely cause of this illness? (10% marks)

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College answer


Post ictal state

Haemorrhage/ oedema secondary to trauma/ non accidental injury



Spontaneous haemorrhage (e.g. first presentation coagulation disorder)

  1. Need to consider likely organisms causing meningoencephalitis in a neonate, common resistance patterns, penetration of the blood brain barrier.

Likely organisms in this age group: Group B streptococci, Listeria monocytogenes, Varicella zoster virus, Herpes simplex virus, Streptococcus pneumonia, Nesseria meningitides, Haemophilus influenza B (too young to be immunised).

E coli and other gram-negative enteric bacilli less likely at this age than in the first week of life, but not unreasonable to cover.

Regime should include: Acyclovir (HSV, VZV)

A third-generation cephalosporin (cefotaxime, ceftriaxone) to cover gram positives as above and gram-negative cover.

Amoxycillin OR Ben Pen to cover Listeria
Vancomycin to cover resistant Pneumococcus.

  1. Bacterial meningitis, Listeria monocytogenes (require organism for full marks)


1) This unconscious febrile neonate with a tense fontanelle: why might they be so, if not infection?


  • Vascular causes:
    • SAH or ICH
  • Neoplastic causes
    • Haematological malignancy
  • Drug-induced caused:
    • DRESS syndrome
    • Serotonin syndrome
    • Malignant hyperthermia
  • Idiopathic causes
    • Febrile convulsions (but this does not explain the fontanelle)
    • Hydrocephalus
    • Coalulation disorder and spontaneous ICH
  • Autoimmune causes
    • CNS vasculitis (unlikely in one so young)
  • Traumatic and environmental causes
    • Non-accidental injury (one would certainly need to mention this to score full marks
    • Heat stroke
  • Endocrine and metabolic  causes
    • Metabolic encephalopathy (and the fever is from aspiration)

Empiric antibiotic regimen:

  • Cefotaxime +  ampicillin (Therapeutic Guidelines)
  • Cefotaxime + vancomycin (Sanford guide, paediatric recommendations)
    • The 3rd generation cephalosporins are here for the usual suspects:
      • S. pneumoniae
      • N. meningitidis
      • H. influenzae
    • The one-month-old population is also prone to:
      • S. agalactiae  (group B strep)
      • E.coli
    • The vancomycin in the Sanford recommendations covers the rare (<10%) community-acquired S.pneumoniae with cephalosporin resistance 
    • Sanford people also recommend ampicillin if there is any suspicion of Listeria
    • None of the guidelines recommend antiviral drugs, but they are routinely given anyway

The most likely cause of this illness

  • Connect the dots:
    • Young infant, not exactly immunocompetent
    • Acute onset of illness
    • Low glucose and high protein in the CSF suggests bacterial infection
    • Gram positive bacilli are rare, and include:
      • Bacillus anthracis
      • Corynebacterium diphtheriae
      • Nocardia asteroides
      • Listeria monocytogenes
      • Clostridium sp.
  • The only plausible agent is therefore Listeria.


NSW Health. Infants and children: acute management of bacterial meningitis: clinical practice guideline. North Sydney: NSW Ministry of Health; 2014.

Tunkel, Allan R., et al. "Practice guidelines for the management of bacterial meningitis." Clinical infectious diseases 39.9 (2004): 1267-1284.