Citrobacter koseri, a facultative gram-negative bacillus, colonizes the intestine and environmental reservoirs. In neonates, especially preterm infants, it can cause severe central nervous system infections (eg, meningitis, encephalitis, abscesses), often with fatal outcomes. Pneumocephalus, an accumulation of intracranial gas, is a rare but deadly complication. We report a preterm female infant admitted to the neonatal intensive care unit (NICU) for respiratory distress who developed high fever and sepsis; blood culture results were positive for C. koseri. Rapid neurological deterioration with seizures occurred, and a cranial computed tomography scan showed extensive pneumocephalus. Despite intensive care, the infant died at 17 days. Autopsy and histology revealed widespread purulent meningitis and meningoencephalitis, pneumocephalus, cerebral hemorrhages, acute edema, and ventricular dilation. An environmental investigation traced the origin of the infection to the bathroom sinks, confirming the nosocomial nature of the pathogen. This case highlights the high virulence of C. koseri in neonates, the catastrophic potential of pneumocephalus, and the crucial importance of strict infection control in NICUs.
