Affiliation:
1. AstraZeneca Pharmaceuticals, Waltham, Massachusetts, USA
2. International Health Management Associates, Inc., Schaumburg, Illinois, USA
Abstract
ABSTRACT
Broth microdilution antimicrobial susceptibility testing was performed for ceftazidime-avibactam and comparator agents against 7,062 clinical isolates of
Pseudomonas aeruginosa
collected from 2012 to 2014 in four geographic regions (Europe, Asia/South Pacific, Latin America, Middle East/Africa) as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance program. The majority of isolates were susceptible to ceftazidime-avibactam, with the proportions susceptible differing marginally across the four regions (MIC
90
, 8 to 16 μg/ml; 88.7 to 93.2% susceptible), in contrast to lower susceptibilities to the following comparator β-lactam agents: ceftazidime (MIC
90
, 32 to 64 μg/ml; 71.5 to 80.8% susceptible), meropenem (MIC
90
, >8 μg/ml; 64.9 to 77.4% susceptible), and piperacillin-tazobactam (MIC
90
, >128 μg/ml; 62.3 to 71.3% susceptible). Compared to the overall population, susceptibility to ceftazidime-avibactam of isolates that were nonsusceptible to ceftazidime (
n
= 1,627) was reduced to between 56.8% (Middle East/Africa; MIC
90
, 64 μg/ml) and 68.9% (Asia/South Pacific; MIC
90
, 128 μg/ml), but these percentages were higher than susceptibilities to other β-lactam agents (0 to 44% susceptible, depending on region and agent; meropenem MIC
90
, >8 μg/ml; 26.5 to 43.9% susceptible). For this subset of isolates, susceptibilities to amikacin (MIC
90
, >32 μg/ml; 53.2 to 80.0% susceptible) and colistin (MIC
90
, 1 μg/ml; 98.5 to 99.5% susceptible) were comparable to or higher than that of ceftazidime-avibactam. A similar observation was made with isolates that were nonsusceptible to meropenem (
n
= 1,926), with susceptibility to ceftazidime-avibactam between 67.8% (Middle East/Africa; MIC
90
, 64 μg/ml) and 74.2% (Europe; MIC
90
, 32 μg/ml) but again with reduced susceptibility to comparators except for amikacin (MIC
90
, >32 μg/ml; 56.8 to 78.7% susceptible) and colistin (MIC
90
, 1 μg/ml; 98.9 to 99.3% susceptible). Of the 8% of isolates not susceptible to ceftazidime-avibactam, the nonsusceptibility of half could be explained by their possession of genes encoding metallo-β-lactamases. The data reported here are consistent with results from other country-specific and regional surveillance studies and show that ceftazidime-avibactam demonstrates
in vitro
activity against globally collected clinical isolates of
P. aeruginosa
, including isolates that are resistant to ceftazidime and meropenem.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology