Comparison of ticarcillin and carbenicillin activity against random and select populations Pseudomonas aeruginosa

The in vitro activities of ticarcillin (T) and carbenicillin (C) against 253 strains of Pseudomonas aeruginosa (108 randomly selected clinical isolates and 145 isolates determined to be C resistant by 10 referring hospitals) were evaluated using both broth microdilution and disk diffusion techniques. T activity was usually twofold or greater than C activity for individual strains in both sample populations. The minimal inhibitory concentration (MIC) values of T and C were 400 (median, 25) and 0.8 to >400 (median, 50) mug/ml, respectively, for the random sample and 1.6 to >400 (median, 50) and 12.5 to >400 (median, 200) mug/ml, respectively, for the select sample. For predicting susceptibility (MIC,