RESUMO
BACKGROUND: In meningitis without germs, the existence of an inflammatory syndrome leads toward a bacterial etiology while the detection of interferon-alpha (IFN-alpha) in the cerebrospinal fluid (CSF) argues for a viral meningitis. The coexistence of the inflammatory syndrome and the presence of IFN-alpha in the CSF makes this differentiation difficult. The reported case yields the picture and begs the question on the diagnostic approach and the required therapeutic attitude. CASE REPORT: A six-week-old infant, exclusively breast-fed, was hospitalized for fever. The examination showed an important inflammatory syndrome and meningeal attempt with a cellularity at 94/mm3 with 53% polymorphonuclear neutrophils, contrasting with normal proteinorrhachia and glycorrhachia. The IFN-alpha in the CSF was present at 4 UI/mL while the bacteriological culture and the viral search by PCR were negative. The clinical and biological worsening within the first 36 hours, in spite of the parenteral dispensation of a triple antibiotic therapy (amoxicillin, ceftriaxone, netilmicin), then a favorable clinical and biological response after adjunction of vancomycin, led toward a pneumococcal meningitis with reduced sensitivity to beta-lactams. The maternal antibiotic therapy by amoxicillin and its presence in the maternal milk favored the hypothesis of a decapitated bacterial meningitis. CONCLUSION: In the presence of a meningitis without germs, the coexistence of a sizable inflammatory syndrome and the detection of IFN-alpha in the CSF must be considered as an unusual phenomenon and motivate the pursuit of antibiotic therapy until viral identification.