Ceftazidime/avibactam tested against Gram-negative bacteria from intensive care unit (ICU) and non-ICU patients, including those with ventilator-associated pneumonia

Int J Antimicrob Agents. 2015 Jul;46(1):53-9. doi: 10.1016/j.ijantimicag.2015.02.022. Epub 2015 Apr 14.


Ceftazidime/avibactam consists of ceftazidime combined with the novel non-β-lactam β-lactamase inhibitor avibactam, which inhibits Ambler classes A, C and some D enzymes. Clinical isolates were collected from 71 US medical centres in 2012-2013 and were tested for susceptibility at a central laboratory by reference broth microdilution methods. Results for 4381 bacterial isolates from intensive care unit (ICU) patients as well as those from ventilator-associated pneumonia (VAP) (n=435) were analysed and compared with those of 14 483 organisms from non-ICU patients. β-Lactamase-encoding genes were evaluated for 966 Enterobacteriaceae by a microarray-based assay. Ceftazidime/avibactam was active against 99.8/100.0% of Enterobacteriaceae (MIC90, 0.25/0.25mg/L) from ICU/non-ICU patients (2948/10,872 strains), including isolates from VAP (99.1%), multidrug-resistant (MDR) strains (99.3%), extensively drug-resistant (XDR) strains (96.5%) and meropenem-non-susceptible strains (98.0%), at MICs of ≤8mg/L. Against Enterobacteriaceae, susceptibility rates for ceftazidime, piperacillin/tazobactam and meropenem (ICU/non-ICU) were 86.1/91.8%, 88.0/94.3% and 97.8/99.2%, respectively. Meropenem was active against 75.1/85.4% of MDR Enterobacteriaceae and 8.1/27.1% of XDR Enterobacteriaceae from ICU/non-ICU patients. When tested against Pseudomonas aeruginosa, ceftazidime/avibactam inhibited 95.6/97.5% of isolates from ICU/non-ICU (842/2240 isolates), 97.3% of isolates from VAP, 80.7% of ceftazidime-non-susceptible and 80.7% of MDR isolates at ≤8mg/L. Susceptibility rates for P. aeruginosa from ICU/non-ICU were 77.7/86.9% for ceftazidime, 71.2/82.2% for piperacillin/tazobactam and 76.6/84.7% for meropenem. In summary, lower susceptibility rates were observed among ICU compared with non-ICU isolates. Ceftazidime/avibactam exhibited potent activity against a large collection of Gram-negative organisms from ICU and non-ICU patients and provided greater coverage than currently available β-lactams.

Keywords: CRE; Carbapenem-resistant Enterobacteriaceae; ESBL; KPC; Pseudomonas aeruginosa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Academic Medical Centers
  • Anti-Bacterial Agents / pharmacology*
  • Azabicyclo Compounds / pharmacology*
  • Ceftazidime / pharmacology*
  • Cross Infection / epidemiology
  • Cross Infection / microbiology*
  • DNA, Bacterial / genetics
  • Drug Combinations
  • Drug Resistance, Bacterial
  • Gram-Negative Bacteria / drug effects*
  • Gram-Negative Bacteria / isolation & purification
  • Gram-Negative Bacterial Infections / epidemiology
  • Gram-Negative Bacterial Infections / microbiology*
  • Humans
  • Intensive Care Units
  • Microarray Analysis
  • Microbial Sensitivity Tests
  • Prevalence
  • United States / epidemiology
  • beta-Lactamases / genetics


  • Anti-Bacterial Agents
  • Azabicyclo Compounds
  • DNA, Bacterial
  • Drug Combinations
  • avibactam, ceftazidime drug combination
  • Ceftazidime
  • beta-Lactamases