Meningitis is very unlikely in otherwise healthy-appearing febrile infants older than 21 days of age. Thus, cerebrospinal fluid analysis might not be needed as part of a “routine” evaluation of these babies.Source:
Martinez E, Mintegi S, Vilar B, Martinez MJ, Lopez A, Catediano E, Gomez B. Prevalence and predictors of bacterial meningitis in young infants with fever without a source. Pediatr Infect Dis J published online 12-2014, doi: 10.1097/INF.0000000000000629.