Background:

Citrobacter species are an unusual cause of cerebral abscess in infant. In particular, Citrobacter freundii can invade and replicate in human brain microvascular endothelial cells with a selective neurovirulence, producing ventriculitis and brain abscess mainly in the infant. A delayed brain abscess caused by C. freundii species in adult patients and after surgery is an occurrence that has not yet been reported in the literature.
Case description:
The authors reported a case of a 60-year-old patient that presented a delayed postoperative brain abscess following resection of a left parietal convexity meningioma. A resurgery was performed, with bone flap removal, debridement, and culture of the purulent content of the previous surgical cavity. The microbiological examination showed the isolation of C. freundii. Postoperatively, the patient improved, with progressive headache reduction and right upper limb weakness improvement. She was continued on medical therapy for 4 weeks, until inflammatory index and white blood cells count gained normal range, then, she was admitted to a neurorehabilitation center.
Conclusion:
A delayed brain abscess caused by C. freundii in adult patients and after surgery is an occurrence that has not yet been reported in the literature, with a consequent complex management, due to the lack of clear guidelines.