Procalcitonin (PCT) has proven its efficacy to distinguish bacterial from
aseptic meningitis in children. Nevertheless, its use in routine is limited by its cost and availability, especially in low- and middle-income countries. It is now acknowledged that eosinopenia is a marker of
infection and/or severity of the systemic inflammatory response. Although no study ever demonstrated that eosinopenia could differentiate bacterial from
viral infection, we decided to conduct a study concerning
meningitis in children. This bicentric and retrospective study was conducted between January 2012 and October 2018, in children hospitalized for
meningitis. The white blood cell was systematically gathered at the admission to evaluate the eosinophil count. Characteristic data were compared between 2 groups: documented
bacterial meningitis (DBP) and
aseptic meningitis which includes documented
viral meningitis (DVM) and non-documented
meningitis (ND). Among 190 patients admitted for
meningitis, 151 were analyzed, including DBM (n = 45), DVM (n = 73), and ND (n = 33)
meningitis. Groups were comparable. Mean age was 33 ± 48 months with a sex ratio of 1.6. Mean of eosinophil count was 15 ± 34/mm3 in the DBM group versus 132 ± 167/mm3 for the
aseptic meningitis group (p < 0.0001). Best threshold for the diagnosis of
bacterial meningitis was an eosinophil count < 5/mm3 with a sensitivity of 80% and specificity of 73% and a likelihood ratio of 2.9. Eosinopenia seems to be a reliable and non-invasive marker of
bacterial meningitis in pediatrics. The absence of extra cost makes it very interesting in low- and middle-income countries or when usual
biomarkers such as PCT are unavailable.