Neonatal Citrobacter koseri Meningitis: Report of Four Cases

Citrobacter koseri is a rare cause of neonatal meningitis with predisposal for brain abscesses, and therefore responsible for high mortality and serious neurologic sequelae in this age group. We present the evolution and outcome of four cases of C. koseri meningitis. One of them developed brain abscesses and another one died. The cases show the bacteria's propensity for serious brain damage, despite early and adequate treatment, and the high risk of long-term neurologic complications in survivors, which imposes a close follow-up. 1. Introduction Citrobacter koseri is a gram-negative bacillus which belongs to the family of Enterobacteriaceae. Although it is rare in the newborn, this bacterium has a strong neurotropism in this age group, causing meningitis and brain abscesses. For this reason, it is associated with high rates of mortality, morbidity, and long-term sequelae [1]. This propensity for C. koseri to damage the central nervous system is still poorly understood. Experimental studies suggest a specific outer membrane protein as the likely neurovirulence factor [2]. Former reports of C. koseri meningitis have been published, most of them associated with neurological complications, including brain abscesses. The authors present the analysis of four cases of C. koseri meningitis, which occurred in a neonatal intensive care unit of a tertiary care hospital, over ten years, emphasizing its clinical acute and long-term neurological complications and comparing them with the published literature on this subject. 2. Case Reports Case 1. A male newborn was born after a 39-week uncomplicated pregnancy by cesarean delivery, with Apgar score 6/8/8 and birth weight 3420？g. He was admitted to the neonatal intensive care unit (NICU) at birth with respiratory distress. By that time he had a normal chest radiograph, white blood count (WBC) and C reactive protein (CRP). He had a favorable outcome without ventilatory support and was discharged at 48 hours of life. He was taken to the emergency department on the sixth day of life with fever, poor feeding, irritability, hypotonia, and poor perfusion. The WBC revealed leukocytosis with neutrophilia and CRP was 2.6？mg/dL. The cerebral spinal fluid (CSF) analysis showed pleocytosis and hypoglycorrachia. Intravenous antibiotic therapy with ampicillin, gentamycin, and cefotaxime was started immediately after collecting culture samples. Still on the first day of admission he had an episode of generalized tonic-clonic seizure solved with a single dose of phenobarbital. Transfontanellar ultrasound (TFUS) performed on the