Antibiotic prophylaxis in ventricular shunt surgery. II. Antibiotic concentrations in cerebrospinal fluid.

Investigation of cerebrospinal fluid (CSF) antibiotic levels from patients operated upon under short-term prophylactic protocols for shunt insertions or revisions revealed low-level CSF penetration by nafcillin and virtually no methicillin activity. Nafcillin levels were not influenced by route of injection or CSF sampling time, but were inversely proportional to ventricular size. The authors recommend nafcillin over methicillin as the preferred prophylactic agent in shunt surgery. Although the 25 mg/kg preoperative dose may be adequate for reducing infection risk, higher dosages should be considered when the ventricles are markedly dilated.