ANALYSIS OF THE INTERACTION BETWEEN PIPERACILLIN AND CIPROFLOXACIN OR TOBRAMYCIN AGAINST THIRTEEN STRAINS OF PSEUDOMONAS AERUGINOSA, USING KILLING CURVES

Abstract

Time-kill studies were made with thirteen strains of Pseudomonas aeruginosa, comparing the activity of ciprofloxacin plus piperacillin with the combination of tobramycin and piperacillin. Synergism was demonstrated in an equal number of strains with both combinations. No antagonism was demonstrated. The reproducibility of the killing-curve method suggests that at least two different concentrations should be used and that a decrease in viable counts below 2 log10 after 24 hours does not exclude a synergistic action.