Penetration of cefoxitin into cerebrospinal fluid of dogs with and without experimental meningitis.

The penetration of cefoxitin into the cerebrospinal fluid (CSF) after slow intravenous infusion of 50-100 mg/kg over 1 hr was studied in normal dogs and in dogs with meningitis experimentally induced by intrathecal injection of 10(9) Staphylococcus aureus. With healthy dogs the peak CSF concentration of 1 microgram of cefoxitin/ml was found to correspond with a serum level of 120 micrograms/ml. With administration of probenecid the CSF level was 1.5 micrograms of cefoxitin/ml. Doubling the dose from 50 to 100 mg/kg resulted in a CSF concentration of 2 micrograms of cefoxitin/ml. In the CSF of animals with meningitis, a peak concentration of 10 micrograms of cefoxitin/ml was obtained 90 min after the start of the infusion, and 5 micrograms/ml was still present at 240 min. The peak level in CSF of animals with meningitis was about 10% of the simultaneous level in serum.