1823. Incidence of Meningoencephalitis in the Absence of CSF Pleocytosis

Abstract

BackgroundCerebrospinal fluid (CSF) pleocytosis, defined here as ≥5 white blood cells (WBC)/high power field (HPF) suggests inflammation of brain parenchyma /meninges or both. However, the absence of pleocytosis does not rule out meningoencephalitis. The frequency with which infectious targets are identified in the absence of CSF pleocytosis is not well known. Traditional diagnostic methods based on culture and single target polymerase chain reaction (PCR) assay were inadequate to answer this question. However, the availability of multiplex (PCR) panels opens up the opportunity.MethodsStarting June of 2016 Akron children’s hospital adopted the Biofire® Meningitis encephalitis panel (MEP). The panel is run routinely on all CSF specimens obtained from patients presenting with a clinical picture consistent with meningoencephalitis irrespective of their CSF biochemistry and cell count Results. We retrospectively collected laboratory data for all the MEP positive patients. The data were filtered based on CSF WBC count, pathogens identified as well as by patient age.ResultsA total of 133 positive results were identified from June 2016 to March 2019. Due to unclear significance, 22 positive Human herpes virus (HHV) 6 results were excluded, One VZV positive result was also excluded (Figure 1). Of the remaining 110 positives, 29% had CSF WBC count < 5/HPF. Parecho and Enterovirus were the most common. Three isolates were positive for Herpes simplex 1 (HSV 1) and one for Herpes simplex 2 (HSV 2). Haemophilus influenzae was detected in one patient (Figure 2).ConclusionOur observations suggest that viral meningoencephalitis may occur frequently in the absence of CSF pleocytosis. Bacterial meningitis seems less likely. Several centers have a policy to restrict multiplex PCR panel testing based on CSF WBC cut-offs, citing increased costs. However, this approach may lead to missed diagnosis. As a direct result of this additional investigations and/or treatment may be pursued leading to increased overall costs as well as exposing the patient to potential harm. Additionally making a diagnosis could lend itself to monitoring outcomes—an area where there is paucity of high-quality data. Disclosures All Authors: No reported Disclosures.