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AJNR Awards, New Junior Editors, and more. Read the latest AJNR updates

Case of the Week

Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada

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Submit a Case Previous Cases ASPNR Pediatric Cases

September 10, 2015
  • Description
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Meningitis, Ventriculitis, and Liquefaction of Periventricular White Matter (Citrobacter koseri)

  • Background:
    • Bacteria of the genus Citrobacter are uncommon neonatal infection agents. Neonates may become infected horizontally (nosocomial infection) or vertically from the mother during delivery.
    • A study by Li et al found that 79% of strains of C. diversus (C. koseri) from cerebrospinal fluid (CSF) had a unique 32-kD outer membrane protein, found in only 9% of non-CSF isolates. C. koseri accounted for only 1.3% of cases of neonatal meningitis reported to the CDC’s Bacterial Meningitis and Meningococcemia Surveillance System.
  • Clinical Information: Classic signs and symptoms include fluctuating fever, seizures, vomiting, lethargy, hypotonia, and bulging fontanelle.
  • Key Diagnostic Features:
    • Hemorrhagic necrosis and liquefaction may occur with or without abscess formation. Brain imaging studies may demonstrate signs of meningitis and cerebritis.
    • There may be debris within the ventricular system, which has a higher T1-weighted signal and lower T2-weighted signal compared to CSF. The debris may show restricted diffusion because of the high protein content and, possibly, necrotic material.
    • Hydrocephalus, periventricular edema, and ependymal enhancement are additional findings that may be seen.
  • DDx:
    • Other bacterial meningoencephalitis with intraventricular pus
    • Viral meningitis
    • Periventricular leukomalacia
    • Peroxisomal disorders
  • Treatment Options: Antibiotics are usually preferred, except for cases with subdural infected collections. However, most authors recommend surgery for accessible cerebral abscesses and ventriculitis evolving with acute hydrocephalus.

Suggested Reading

Doran TI. The role of Citrobacter in clinical disease of children: a review. Clin Infect Dis 1999;28:384–94, 10.1086/515106

Marecos CV, Ferreira M, Ferreira MM, et al. Sepsis, meningitis and cerebral abscesses caused by Citrobacter koseri. BMJ Case Rep 2012, published online January 27, 2012, 10.1136/bcr.10.2011.4941

Fukui MB, Williams RL, Mudigonda S. CT and MR imaging features of pyogenic ventriculitis. AJNR Am J Neuroradiol 2001;22:1510–16

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American Journal of Neuroradiology: 46 (6)
American Journal of Neuroradiology
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