Bacillus cereus bacteremia with central nervous system involvement: A neuropathological study.

<i>Bacillus cereus</i> is a widely-distributed, gram-positive or variable, rod-shaped bacterium frequently considered a contaminant in clinical specimens. It is recognized as a potential pathogen inducing self-limiting emetic or diarrheal food poisoning or localized infection in immunocompetent patients. True <italic>B. cereus</italic> bacteremia is uncommon and mainly observed in fragile patients, notably in immunocompromised individuals. We report clinical, radiological, and pathological findings of a 64-year-old patient with a history of acute myeloid leukemia who initially presented a fever while neutropenic after the induction of a second cycle of chemotherapy. He developed <italic>B. cereus</italic> bacteremia with invasive infection and a fatal outcome. The clinical and radiological data of this case are compared to a previously-published series of 21 patients from our institution with <italic>B. cereus</italic> bacteremia. This study highlights the clinical challenge to diagnose <italic>B. cereus</italic> and the importance of the delay between the detection of <italic>B. cereus</italic> and the initiation of an effective targeted antibiotic therapy. This case presented an aggressive evolution with multiple necrotic and hemorrhagic foci in the brain. Upon histological examination, <italic>B. cereus</italic> virulence was notably reflected by the dissection of blood vessel walls by the bacilli and luminal occlusion, a pattern that has not been yet reported.