Cerebrospinal fluid penetration of high doses of intravenous ciprofloxacinin meningitis

Nosocomial meningitis due to gram-negative organisms is a difficult clinica l problem to manage because of both antibiotic resistance and poor penetrat ion of many antimicrobials across the blood-brain barrier. Ciprofloxacin ha s potential in treating this condition when used in high doses. We investig ated the plasma and cerebrospinal fluid (CSF) levels of ciprofloxacin in a patient with Pseudomonas aeruginosa meningitis who was treated with 400 mg of intravenous ciprofloxacin every 8 hours. Ciprofloxacin levels in plasma peaked at 10.29 mg/L without resulting in accumulation (8-hour trough level s, <1 mg/L), whereas the CSF level increased to 0.9 mg/L. This CSF level wa s confirmed to be similar 1 week later. After 1 week of therapy, during whi ch there were no side effects attributable to ciprofloxacin, the organism w as eradicated, and there was some clinical improvement. We recommend that 4 00 mg of intravenous ciprofloxacin every 8 hours be considered for treatmen t of difficult-to-treat gram-negative bacillary meningitis.