{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,11]],"date-time":"2025-12-11T20:51:58Z","timestamp":1765486318994,"version":"3.41.2"},"reference-count":21,"publisher":"Oxford University Press (OUP)","issue":"6","license":[{"start":{"date-parts":[[2019,5,21]],"date-time":"2019-05-21T00:00:00Z","timestamp":1558396800000},"content-version":"vor","delay-in-days":1,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004334","name":"Merck & Co., Inc.","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100004334","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2019,6,1]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Pseudomonas aeruginosa remains an important cause of hospital-acquired infections in the United States and is frequently multidrug-resistant (MDR). The Infectious Diseases Society of America guidelines recommend empiric combination therapy that includes an antipseudomonal \u03b2-lactam with an aminoglycoside or fluoroquinolone likely to cover \u226595% of P. aeruginosa infections in seriously ill patients at risk of having an MDR pathogen. Ceftolozane is an antipseudomonal cephalosporin, combined with the \u03b2-lactamase inhibitor tazobactam. Ceftolozane-tazobactam is approved for treatment of complicated urinary tract infections and complicated intra-abdominal infections. A phase 3 clinical trial for the treatment of hospital-acquired pneumonia including ventilator-associated pneumoniae was recently completed. We compared the in vitro susceptibility rate of ceftolozane-tazobactam with the cumulative susceptibility rates of antibiotic combinations commonly used against P. aeruginosa.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Isolates were collected from intensive care unit patients hospitalized in 32 US hospitals from 2011 to 2017. The susceptibilities of 1543 P. aeruginosa isolates from bloodstream infections (198 isolates, 12.8%) or pneumonia (1345 isolates, 87.2%) were determined for ceftolozane-tazobactam and comparators.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The most active antimicrobials were colistin (99.4% susceptible), amikacin (98.1% susceptible), and ceftolozane-tazobactam (96.5% susceptible). The susceptibilities to other antipseudomonal \u03b2-lactams and fluoroquinolones were &amp;lt;84%. A cumulative susceptibility of \u226595% was reached for cefepime, ceftazidime, meropenem, and piperacillin-tazobactam only in combination with amikacin due to the lower susceptibilities of gentamicin, ciprofloxacin, and levofloxacin. Monotherapies that exceeded 95% were ceftolozane-tazobactam, amikacin, and colistin.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Ceftolozane-tazobactam monotherapy is likely to be active against more isolates than a combination of another \u03b2-lactam and a fluoroquinolone or gentamicin for serious P. aeruginosa infections.<\/jats:p><\/jats:sec>","DOI":"10.1093\/ofid\/ofz240","type":"journal-article","created":{"date-parts":[[2019,5,21]],"date-time":"2019-05-21T07:19:57Z","timestamp":1558423197000},"source":"Crossref","is-referenced-by-count":10,"title":["Comparison of the In Vitro Susceptibility of Ceftolozane-Tazobactam With the Cumulative Susceptibility Rates of Standard Antibiotic Combinations When Tested Against Pseudomonas aeruginosa From ICU Patients With Bloodstream Infections or Pneumonia"],"prefix":"10.1093","volume":"6","author":[{"given":"Dee","family":"Shortridge","sequence":"first","affiliation":[{"name":"JMI Laboratories, North Liberty, Iowa"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael A","family":"Pfaller","sequence":"additional","affiliation":[{"name":"JMI Laboratories, North Liberty, Iowa"},{"name":"University of Iowa College of Medicine, Iowa City, Iowa"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S J Ryan","family":"Arends","sequence":"additional","affiliation":[{"name":"JMI Laboratories, North Liberty, Iowa"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Janet","family":"Raddatz","sequence":"additional","affiliation":[{"name":"Merck & Co, Inc., Kenilworth, New Jersey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daryl D","family":"DePestel","sequence":"additional","affiliation":[{"name":"Merck & Co, Inc., Kenilworth, New Jersey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert K","family":"Flamm","sequence":"additional","affiliation":[{"name":"JMI Laboratories, North Liberty, 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