Penetration of fusidic acid and rifampicin into cerebrospinal fluid in low-grade inflammatory meningitis caused by Staphylococcus epidermidis

Cerebrospinal fluid (CSF) concentration-time curves of rifampicin and fusidic acid were studied in a patient with post-operative meningitis caused by Staphylococcus epidermidis. The patient was treated with this combination of antimicrobial agents because of a severe hypersensitivity reaction to vancomycin. Peak CSF concentrations of rifampicin exceeded the MIC by > 60-fold, while those of fusidic acid just reached the MIC. CSF concentrations of fusidic acid were relatively stable within the range reported for patients with uninflamed meninges, but serum levels were surprisingly low. An increase in the metabolism of fusidic acid induced by rifampicin cannot be excluded.