Acute bacterial meningitis without cerebrospinal fluid pleocytosis in children: results from a nationwide prospective surveillance system between 2001 and 2022

Objectives

We aimed to describe cases of acute bacterial meningitis (ABM) without cerebrospinal fluid (CSF) pleocytosis and the clinical and biological characteristics of affected children.

Methods

We analyzed results of a nation-wide population-based prospective surveillance study of acute ABM in children aged 3 months to 15 years in France. Absence of CSF pleocytosis was defined as CSF leukocyte count ≤5/mm³.

Results

We included 4754 cases of acute ABM from 2001 to 2022: 173 patients (3.6%) did not have CSF pleocytosis. ABM cases without CSF pleocytosis were mainly related to meningococcus (70% vs 44% with CSF pleocytosis, P <0.001). When performed in CSF with normal leukocyte count, Gram staining results were positive for 33%, culture for 80%, polymerase chain reaction results for 41%, and antigen detection for 20% of cases. Case fatality rate was higher for cases without than those with CSF pleocytosis (18% vs 6%, P <0.001). On multivariate analysis, absence of CSF pleocytosis was associated only with seizures before hospital arrival (adjusted odds ratio 2.3, 95% confidence interval 1.2-4.6, P <0.01).

Conclusions

ABM without CSF pleocytosis is infrequent but not exceptional, particularly in children with seizures before hospital arrival. Extended vaccination against meningococcus could prevent this clinical form with a high case fatality rate.