Parenteral trimethoprim/sulfamethoxazole for gram-negative bacillary meningitis.

Three adults with gram-negative bacillary meningitis were treated with an intravenous preparation of trimethoprim and sulfamethoxazole. This therapy sterilized the cerebrospinal fluid in each case. The infections occurred as complications of neurosurgery, trauma and chronic otitis media. Serratia marcescens was the causative organism in two patients and Proteus vulgaris in the third. The infecting organism was eradicated within three to 17 days of beginning intravenous trimethoprim/sulfamethoxazole. Followup CSF cultures after completing therapy were sterile. These cases suggest intravenous trimethoprim/sulfamethoxazole may be effective treatment for some cases of gram negative bacillary meningitis.