Changes in pharmacodynamic target attainment for antimicrobials over a 2-year period: Results of the 2004 OPTAMA program in North America

The Optimizing Pharmacodynamic Target Attainment using a Microbiology Antibiogram (OPTAMA) program aims to determine the likelihood that specific antibiotic regimens will achieve bactericidal pharmacodynamic exposures against common nosocomial pathogens. The pharmacokinetic profiles of 5000 subjects were simulated to determine the bactericidal cumulative fraction of response (CFR) for commonly used intravenous β2-lactams and ciprofloxacin against Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, and Klebsiella species, isolated during the 2004 Meropenem Yearly Susceptibility Test Information Collection surveillance study in North America. Bactericidal CFRs were compared with 2002 OPTAMA results to assess for trends. Compared with 2002 results, declines in susceptibility, with a corresponding decrease in CFR, were observed for many agents against P. aeruginosa and A. baumannii, and for ciprofloxacin against E. coli. Conversely, discordance was observed with ciprofloxacin against Klebsiella species. Among this current population of nosocomial-acquired Gram negatives, the ability to achieve optimal pharmacodynamic exposures is becoming more difficult because of increasing resistance; therefore, continual evaluation of optimal dosing strategies will be necessary. Copyright © 2007 by Lippincott Williams & Wilkins.