Impact of MIC range for Pseudomonas aeruginosa and Streptococcus pneumoniae on the ceftolozane in vivo pharmacokinetic/pharmacodynamic target.

Ceftolozane is a novel cephalosporin with activity against drug-resistant pathogens, including Pseudomonas aeruginosa and Streptococcus pneumoniae. The in vivo investigation reported here tested the limits of this drug against 20 P. aeruginosa and S. pneumoniae isolates across a wide MIC range and defined resistance mechanisms. The times above the MIC (T>MIC) targets for stasis and 1- and 2-log reductions were 31%, 39%, and 42% for P. aeruginosa and 18%, 24%, and 27% for S. pneumoniae, respectively. The 1-log endpoint was achieved for strains with MICs as high as 16 μg/ml.