Prevalence and predictors of bacterial meningitis in young infants with fever without a source

Classical criteria differ when performing cerebrospinal fluid (CSF) analysis in infants younger than 90 days with fever without a source (FWS). Our objectives were to analyze the prevalence and microbiology of bacterial meningitis in this group and its prevalence in relation to clinical and laboratory risk factors.

This is a substudy of a prospective registry including all infants of this age with FWS seen between September 2003 and August 2013 in a Pediatric Emergency Department of a Tertiary Teaching Hospital.

Lumbar puncture was performed in 639 (27.0%) of the 2362 infants with FWS seen, the rate being higher in not well-appearing infants [60.9% vs. 25.7%; odds ratio (OR), 4.49] and in those ≤21 days old (70.1% vs. 20.4%; OR, 9.14). Eleven infants were diagnosed with bacterial meningitis: 9 were ≤21 days old (prevalence 2.8% vs. 0.1%; OR, 30.42) and 5 were not well-appearing infants (5.7% vs. 0.2%; OR, 23.06). Bacteria isolated were Streptococcus agalactiae (3), Escherichia coli (3), Listeria monocytogenes (3), Streptococcus pneumoniae (1) and Neisseria meningitidis (1). None of the 1975 well-appearing infants >21 days old were diagnosed with bacterial meningitis, regardless of whether biomarkers were altered.

In infants younger than 90 days with FWS, performing CSF analysis for ruling out bacterial meningitis must be strongly considered in not well-appearing infants and in those ≤21 days old. The recommendation of systematically performing CSF analysis in well-appearing infants 22-90 days of age on the basis of analytical criteria alone must be reevaluated.