3 Citrobacter/Enterococcus Brain Abscess of Newborn

Clinical Presentation

The first case shows a 1-week-old premature neonate, born after premature rupture of the membranes. Case 1 presents with severe neonatal sepsis (Fig. 3A) and late change is shown in the second case (Fig. 3B).

Figure 3A

Figure 3B

Radiologic Findings

Figs. 3A1 and 3A2 show a 1-week-old neonate. Ultrasonography performed in the early stage of the disease (Fig. 3A1) demonstrates diffuse, increased echogenicity of the anterior part of the brain, especially on the left. Subsequent enhanced CT (Fig. 3A2) demonstrates large, necrotic cavitations with no mass effect and little enhancement in the white matter of both frontal lobes. Figs. 3B1 to 3B4 show the late changes in a 3-month-old child (different from the child pictured in Figs. 3A1 and 3A2) who survived the infection; the nonenhanced T1-weighted (Fig. 3B1), FLAIR (Fig. 3B2), and T2-weighted (Fig. 3B3) imaging shows massive and diffuse loss of white matter with multiple cysts of different signals, of which one in the posterior right hemisphere appears to be hemorrhagic. On the enhanced T1-weighted image (Fig. 3B4), the dense, presumably hemorrhagic lesion demonstrated a marked ring enhancement.

Diagnosis

Neonatal Citrobacterbrain abscesses

Differential Diagnosis

Sepsis in a neonate is a clinical, laboratory, and therapeutic problem. Diagnostic imaging is needed to confirm the diagnosis of meningocerebral involvement, to stage the brain infection, and to appreciate the complications. Therefore, the differential diagnosis is somewhat theoretical.
Other bacterial abscesses: At this age, all have a severe prognosis if not treated early and efficiently. The early identification of the germ and the efficacy of treatment depend on laboratory, not on imaging, studies.
Citrobacterinfections tend to cavitate: It is important not to mistake these cavitations in the white matter for sequelae of an earlier ischemic or hemorrhagic insult. Contrast-enhanced studies will demonstrate the infection-related enhancement.
Other mass lesions: Congenital/neonatal tumors are uncommon (choroid plexus papillomas, craniopharyngiomas, teratomas, atypical teratoid/rhabdoid tumors). Even when partly cystic, they present solid, nodular components different from the inflammatory ring of a cerebral infection. Diffusion imaging may help as diffusion is restricted in abscesses.
Early cerebritis should not be mistaken for normal, immature white matter, nor for cicatricial leukomalacia.