A persistent biochemical marker for partially treated meningitis/ventriculitis

Regulation of circulating iron is important in bacterial, yeast, and fungal infections. In the present study, cerebrospinal fluid levels of ferritin, an iron-binding protein, were determined in controls and in patients with central nervous system pyogenic and viral infections. Among 441 controls, cerebrospinal fluid ferritin level was higher than 18 ng/mL in two relapsed patients with central nervous system leukemia, 12 with bacteremia or pneumonia, and one with hemorrhagic herpes simplex encephalitis. Cerebrospinal fluid ferritin levels were more than 18 ng/mL in 13 of 63 patients diagnosed with nonhemorrhagic aseptic meningitis/ventriculitis, when defined solely by negative cerebrospinal fluid culture. Conversely, cerebrospinal fluid ferritin exceeded 18 ng/mL in culture-proven meningitis (46 of 47 cases) and ventriculitis (five of five cases). Cases of indolent cryptococcus and tuberculous meningitis showed modest increases despite traditional cerebrospinal fluid markers, at times, being normal. Cerebrospinal fluid ferritin levels did not correlate with cerebrospinal fluid neutrophil count, cerebrospinal fluid protein concentration, serum ferritin level, or patient age. In 16 of 19 cases monitored sequentially during ongoing antibiotic treatment, levels remained over 18 ng/mL (average, 15.0 days; range, 1 to 54 days). This observation suggests that obtaining cerebrospinal fluid ferritin levels is helpful whenever traditional laboratory benchmarks normalize, as during acute or chronic antibiotic therapy, or create confusion with positive cultures stemming from sample contamination.