title: Pseudomonas aeruginosa Antimicrobial Susceptibility Results from Four Years (2012 to 2015) of the International Network for Optimal Resistance Monitoring Program in the United States.
abstract: Pseudomonas aeruginosarepresents a major cause of health care-associated infections, and inappropriate initial antimicrobial therapy is associated with increased morbidity and mortality. The International Network for Optimal Resistance Monitoring (INFORM) program monitors thein vitroactivity of ceftazidime-avibactam and many comparator agents. We evaluated the antimicrobial susceptibility of 7,452P. aeruginosaisolates collected from 79 U.S. medical centers in 2012 to 2015. The isolates were collected and tested consecutively for susceptibility by broth microdilution method. Infection types included mainly pneumonia (50.5%), skin and skin structure (24.0%), urinary tract (7.8%), and bloodstream (7.7%) infections. The only compounds with >90% susceptibility rates were colistin (MIC50/90, 1/2 mg/liter, respectively; 99.4% susceptible), ceftazidime-avibactam (MIC50/90, 2/4 mg/liter, respectively; 97.0% susceptible), and amikacin (MIC50/90, 2/8 mg/liter, respectively; 97.0/93.0% susceptible [CLSI/EUCAST, respectively]). The addition of avibactam to ceftazidime increased the percentage of susceptibleP. aeruginosaisolates from 84.3% to 97.0%. Multidrug resistance (MDR) and extensive drug resistance (XDR) phenotypes were observed among 1,151 (15.4%) and 698 (9.4%) isolates, respectively, and ceftazidime-avibactam inhibited 82.1 and 75.8% of these isolates at ≤8 mg/liter, respectively. High rates of cross-resistance were observed with ceftazidime, meropenem, and piperacillin-tazobactam, whereas ceftazidime-avibactam retained activity against isolates nonsusceptible to ceftazidime (81.0% susceptible), meropenem (86.2% susceptible), and piperacillin-tazobactam (85.4% susceptible), as well as isolates nonsusceptible to these three β-lactams (71.2% susceptible). The only antimicrobial combinations that provided a better overall anti-Pseudomonascoverage than ceftazidime-avibactam (97.0% susceptibility rate) were those including amikacin (97.0 to 98.4% coverage). Susceptibility rates remained stable during the study period. The results of this investigation highlight the challenge of optimizing empirical antimicrobial therapy forP. aeruginosainfections.
authors.affiliation: JMI Laboratories, North Liberty, Iowa, USA helio-sader@jmilabs.com.
authors.forename: Helio S
authors.initials: HS
authors.lastname: Sader
authors.affiliation: JMI Laboratories, North Liberty, Iowa, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Huband
authors.affiliation: JMI Laboratories, North Liberty, Iowa, USA.
authors.forename: Mariana
authors.initials: M
authors.lastname: Castanheira
authors.affiliation: JMI Laboratories, North Liberty, Iowa, USA.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Flamm
mesh_terms: D000583:Amikacin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D053961:Azabicyclo Compounds / Q000494:pharmacology*; D016470:Bacteremia / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D002442:Ceftazidime / Q000494:pharmacology*; D003091:Colistin / Q000494:pharmacology*; D004338:Drug Combinations; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D007391:International Cooperation; D008826:Microbial Sensitivity Tests; D018410:Pneumonia, Bacterial / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D062486:Public Health Surveillance; D012874:Skin Diseases, Infectious / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D053961:Azabicyclo Compounds; D004338:Drug Combinations; C000595613:avibactam, ceftazidime drug combination; D000583:Amikacin; D002442:Ceftazidime; D003091:Colistin
keywords: antimicrobial resistance; ceftazidime-avibactam; health care-associated infection