Background and aims Bacterial ventriculitis is common in children with temporary external ventricular drains and diagnosis is challenging due to frequent reoperations, blood contamination of cerebrospinal fluid (CSF), presence of chemical ventriculitis and elevation of blood laboratory markers by concomitant bacterial infection.

Methods Prospective, observational study enrolling children with external ventricular drainage at surgical ward and paediatric intensive care unit. CD64in in CSF together with CSF leukocyte count, glucose, proteins and blood leukocyte and differential count, CRP, PCT were studied at the time of suspected ventriculitis. CD64in was measured by flow cytometry (Trillium Diagnostics, LLC, Brewer, ME). Wilcoxon-test was used for comparison between groups and diagnostic accuracy determined by the area under the ROC curves (AUC) was defined for each marker.

Results Thirty-three episodes of clinically suspected ventriculitis in twenty-one children (male 14, female 7, median age: 9 months, range: 8 days-167 months) were observed during a 26-month period. Episodes were classified into those with microbiologically proven ventriculitis (13 episodes: 9 Gram-positive and 4 Gram-negative) and those with microbiologically negative CSF (20 episodes). CD64in was the only CSF marker that could differentiate between groups (p = 0.0003); its diagnostic accuracy was 0.875 (95% CI: 0.713–0.963). Among blood markers only CRP and band neutrophils differentiated between groups (p = 0.0032 and p = 0.0463) with their diagnostic accuracy of 0.808 (0.633–0.923) and 0.721 (0.524–0.870); respectively.

Conclusions CD64in in CSF is a promising diagnostic marker of bacterial ventriculitis in children with external ventricular drainage before microbiological confirmation.