MICROBIOLOGIC EFFECT OF BOVINE CEREBROSPINAL-FLUID AND AZITHROMYCIN AGAINST NEISSERIA-MENINGITIDIS, STREPTOCOCCUS-PNEUMONIAE, AND HAEMOPHILUS-INFLUENZAE

Minimum inhibitory concentrations (MICs) and minimum bactericidal conc entrations (MBCs) of azithromycin against reference strains of Strepto coccus pneumoniae ATCC 49619, Neisseria meningitidis ATCC 13090, and H aemophilus influenzae ATCC 49247 were determined by the macrodilution broth method with and without 10% bovine cerebrospinal fluid (CSF) sup plementation. The MICs and MBCs were within one to two dilutions for N . meningitidis and S. pneumoniae, and no difference was observed for H . influenzae. Time-kill curves demonstrated enhanced killing by azithr omycin when 10% bovine CSF was added to media for N. meningitidis. The minimum azithromycin concentration for a greater than 3 log(10) reduc tion in inoculum with bovine CSF was 0.03 mu g/ml and without CSF was 0.12 mu g/ml, a 3-fold difference. Killing was not significantly diffe rent for either H. influenzae nor S. pneumoniae.