Elevated production of radical oxygen species by polymorphonuclear neutrophils in cerebrospinal fluid infection

BACKGROUND Central nervous system infection is a daily concern in neurointensive care; however, diagnosis remains difficult because classical criteria based on cerebrospinal fluid (CSF) analysis are difficult to interpret in post-trauma or neurosurgery patients after recent bleeding. A rapid, specific, sensitive test to diagnose CSF infection would help streamline therapeutic decisions in clinical practice and limit the risk of multiresistant bacteria. We hypothesized that polymorphonuclear neutrophil (PMN) phenotype and radical oxygen species (ROS) production in CSF may be specific to the presence of infection. METHODS This study included 30 patients with suspected CSF infection with ventricular hemorrhage requiring external ventricular drainage, and 13 patients after trauma or surgery. Criteria for evaluating CSF infection included positive culture and > 100 leukocytes/mm3. Analysis of PMN phenotype was performed using flow cytometry (CD16, CD11b, and CD62L). ROS production was analyzed through luminometry (luminol). RESULTS Infected CSF exhibited higher production of ROS compared with noninfected CSF. PMNs in CSF exhibited low CD16 and high annexin V expression, suggesting apoptosis. CONCLUSIONS Measurement of ROS production may discriminate infected from noninfected CSF. This simple test would be easy to employ in clinical practice to improve CSF infection management.