Diagnostic imaging of Bacillus cereus brain infection in newborns.

Abstract

Background: Cerebral infection with the opportunistic pathogen Bacillus cereus can lead to severe lesions, especially in premature newborns. Early diagnosis would be highly beneficial. The aim of this study was to describe the imaging findings associated with B. cereus infections.

Materials and methods: We included all newborns with a positive B. cereus blood culture and transfontanellar ultrasound between 2012 and 2022 at the Tours University Hospital. Imaging was assessed by both a junior and a senior radiologist to differentiate between hemorrhages, leukomalacia, and lesions attributed to B. cereus.

Results: Nineteen patients were enrolled (12 girls), of whom 18 were premature. Three patients did not survive. Six patients had normal ultrasound and brain magnetic resonance imaging (MRI) scans. Thirteen patients had ultrasound-detected lesions: 7 hemorrhages, 1 case of leukomalacia, 1 focal ischemic lesion, and 5 lesions attributed to B. cereus. The B. cereus lesions appeared as irregular (5/5), bilateral (4/5), asymmetric (5/5), and hyperechoic patches in the subcortical white matter. They were extensive, asynchronous, and rapidly progressive over a few days (central necrosis with peripheral enhancement, referred to as the "bear scratch sign"), while respecting the cortex and basal ganglia.

Conclusion: The presence of rapidly evolving white matter lesions should raise suspicion of B. cereus infection in newborns' brains. Imaging plays a crucial role in estimating the progression of this pathology.