Sometimes the only indicator of a serious infection in a neonate is a fever. Citrobacter koseri (C. koseri) has been reported to cause neonatal brain abscesses in the setting of meningitis. Although rare, pneumocephalus, secondary to C. koseri , carries a very high mortality. A 17-day-old male presented to the emergency department with a fever, decreased oral intake, and lethargy. The patient developed pneumocephalus and cerebral edema and was diagnosed with C. koseri meningitis, leading to death. This case demonstrates the presentation of C. koseri meningitis with pneumocephalus and cerebral edema in a neonate presenting with fever.