Cefotaxime levels in ventricular cerebrospinal fluid, determined by bioassay and by high-performance liquid chromatography.

Five series of cerebrospinal fluid (CSF) samples, obtained from external ventricular drains (EVD) of 4 neurosurgical patients with cefotaxime treatment were tested simultaneously by high-performance liquid chromatography (HPLC) and microbioassay using E. coli V 6311/65 as test organism. Higher cefotaxime (CTX) concentrations in CSF were measured by the microbioassay method in 4 of the 5 series, reflecting the microbioassay being influenced by increasing amounts of desacetyl-cefotaxime (DAC) during the post-application interval. Decrease of CTX levels in CSF was consistently faster in tests performed by HPLC than those using microbioassay. The clinical efficacy in gram-negative bacillary meningitis is to be explained by levels of the parent compound CTX in CSF which are several times higher than the minimal inhibitory concentrations (MICs) of most enterobacteriaceae.