Global trends of antimicrobial susceptibility of ceftaroline and ceftazidime-avibactam: a surveillance study from the ATLAS program (2012-2016)

Background: This study reports the global trends of antimicrobial susceptibility toceftaroline and ceftazidime-avibactam using data from the Antimicrobial Testing Leadership And Surveillance (ATLAS)programbetween2012and2016. Methods: : For the 2012-2016 ATLAS program, 205 medical centers located in Africa-Middle East (n=12), Asia-Pacific (n=32), Europe (n=94), Latin America (n=26), North America (n=31), and Oceania (n=10) consecutively collected the clinical isolates. Theminimum inhibitory concentrations (MICs) and in vitro susceptibilities toceftarolineandceftazidime-avibactam were assessed using the Clinical andLaboratory Standards Institute (CLSI) 2019and European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2019 guidelines. Results: : Between 2012 and 2016, 176,345 isolates were collectedfrom around the globeand included in theanalysis.Regarding Gram-negative bacteria, ceftazidime-avibactam demonstrated high susceptibility (>90%) against Enterobacteriaceae and Pseudomonas aeruginosa, with increasedantimicrobial activity observed from the addition of avibactam (4 mg/L) to ceftazidime.Regarding Gram-positive bacteria, ceftaroline showed >90% susceptibility against Staphylococcus aureus , Streptococcus pneumoniae , α-and β-hemolytic Streptococcus .The antimicrobial susceptibilitiestoceftaroline and ceftazidime-avibactam were mostly stable from 2012 to 2016, but the susceptibilitiestoceftazidime-avibactam to carbapenem-resistant (CR) Klebsiella pneumoniae (88.4% to 81.6%) and to CR- Pseudomonas aeruginosa (89.6% to 72.7%) decreased over time. In terms of regional difference, the susceptibilities of methicillin-resistant Staphylococcus aureus to ceftaroline in Asia and of CR- Klebsiella pneumoniae to ceftazidime-avibactam in Asia/Africa-Middle East were lowercompared with other regions,while the susceptibility of CR- Pseudomonas aeruginosa to ceftazidime-avibactam in North America was higher. Conclusion: The addition of avibactam improves the activity of ceftazidime against Enterobacteriaceae and Pseudomonas aeruginosa. The global antimicrobial susceptibilitiestoceftaroline and ceftazidime-avibactam were, in general, stable from 2012 to 2016, but a marked reduction in the susceptibilities of specific species andCR- Pseudomonas aeruginosa toceftazidime-avibactam was observed.