In vitro activity of ciprofloxacin combined with azlocillin

A ciprofloxacin plus azlocillin broth microdilution checkerboard was evaluated against 125 aerobic gram-negative and gram-positive bacteria. Synergism (sigma FIC less than or equal to 0.5) occurred among 56% of Pseudomonas aeruginosa, 30% of Acinetobacter species, and 40% of Staphylococcus aureus studied. Antagonism (sigma FIC greater than or equal to 2) was present in less than 1% of the organisms.