Brain Abscesses Due to Citrobacter koseri in a Pair of Twins

Abstract

To the Editors: Intracranial abscesses are uncommon in the newborn and have not been reported in a pair of twins. We describe Citrobacter meningitis complicated by multiple brain abscesses. These dizygotic twins were born by normal delivery, following induced labor at 37 weeks gestation. The babies were healthy at birth, weighing 2.18 kg and 2.30 kg. Perinatally, there were no prolonged ruptures of membranes, maternal fever, or illness. The twins were bottle-fed on formula and discharged home on day five. Twin 1 presented with a temperature of 37.8°C and a history of jerky movements on day 21 of life. Cerebrospinal fluid (CSF) analysis from lumbar puncture showed elevated white cell count of 5250 × 106/L (90% polymorphs, 10% lymphocytes). No organism was seen on Gram stain but culture yielded scanty growth of Citrobacter koseri. No organism was isolated from blood cultures. Twin 2 was asymptomatic but also had CSF obtained which showed 30 × 106/L white blood cells. No organism was isolated from the CSF or blood. Both babies were empirically treated with intravenous cefotaxime. Despite in vitro susceptibility of the organism to cefotaxime, both babies developed brain abscesses, evident on brain imaging at the end of the first week of treatment (Fig., Supplemental Digital Content 1, https://links.lww.com/INF/A260 and Fig., Supplemental Digital Content 2, https://links.lww.com/INF/A261). Intravenous meropenem was added in the second week but the abscesses continued to increase in size. On day 22 of antibiotic treatment the abscesses were drained by stereotactic needle aspiration; pus from the frontal abscesses in twin 2 grew Citrobacter koseri. Both babies remained clinically well throughout their hospitalization. Echocardiograms did not show cardiac abnormality to account for possible cerebral embolizsation. Four weeks of intravenous meropenem was completed and the babies were discharged home on further 3 months therapy for oral ciprofloxacin. At 4 months of age both babies were neurologically normal with resolution of cerebral abscesses on CT scans but persistence of a porencephalic cyst in twin 1 (Fig., Supplemental Digital Content 1, https://links.lww.com/INF/A260 and Fig., Supplemental Digital Content 2, https://links.lww.com/INF/A261). Citrobacter species are anaerobic Gram negative rods found infrequently as normal inhabitants of the intestinal tract of human and animals.1Citrobacter accounts for up to 4% of neonatal meningitis cases,2Citrobacter koseri (formerly Citrobacter diversus) being the most common species implicated.3 Newborns can acquire colonization at the time of passage through the birth canal of a colonized mother.4Citrobacter infection almost always results in meningitis but the mechanism for the neurotropism of this organism is not fully understood. Meningitis leads to intracerebral abscesses in 75% of cases.3 Case-fatality rate for Citrobacter meningitis of 30% has been observed, with at least 50% of surviving infants having neurologic sequelae.3 As our case demonstrates, bacteria can be cultured from abscesses despite systemic antibiotics, and also despite good concentration of antibiotics within the cavity.5 Neurosurgical management is therefore advocated: goals of abscess aspiration include removal of the mass effect, and reduction of the bacterial load thereby improving the local environment for systemic antibiotics to have their effect. This case report also highlights the increased risk of infection in the asymptomatic twin of an affected infant. Onajite Etuwewe, MB ChB, MRCPCH Department of Paediatric Infectious Diseases and Immunology Richa Kulshrestha, MB BS, MRCPCH Department of Neurology Meharpal Sangra, FRCS Department of Neurosurgery Andrew Riordan, MD, DTM&H, MRCP(UK), FRCPCH Department of Paediatric Infectious Diseases and Immunology Alder Hey Children's NHS Foundation Trust Liverpool, United Kingdom