Abstract
Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of azithromycin against reference strains of Streptococcus pneumoniae ATCC 49619, Neisseria meningitidis ATCC 13090, and Haemophilus influenzae ATCC 49247 were determined by the macrodilution broth method with and without 10% bovine cerebrospinal fluid (CSF) supplementation. 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 azithromycin when 10% bovine CSF was added to media for N. meningitidis. The minimum azithromycin concentration for a greater than 3 log
10 reduction in inoculum with bovine CSF was 0.03 μg/ml and without CSF was 0.12 μg/ml, a 3-fold difference. Killing was not significantly different for either H. influenzae nor S. pneumoniae.