LAUSR

Ceftaroline fosamil, the prodrug of ceftaroline, is a parenteral cephem approved for the treatment of patients with skin and skin structure infections (SSSIs) caused by Staphylococcus aureus (both methicillin-susceptible [MSSA] and methicillin-resistant [MRSA] isolates), β-hemolytic streptococci (Streptococcus pyogenes, Streptococcus agalactiae), and select species of Enterobacterales (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca). The current study is part of the ATLAS (Antimicrobial Testing Leadership and Surveillance) program and evaluated the current activities of ceftaroline and comparator agents against commonly encountered bacterial isolates associated with SSSIs. From 2012 to 2018 the ATLAS program received 90,119 bacterial isolates that had been cultured by 370 clinical laboratories in 56 countries from samples of patients diagnosed with SSSIs. All isolates were transported to IHMA, Inc., (Schaumburg, IL, USA) where their identities were confirmed using MALDI-TOF mass spectrometry and antimicrobial susceptibility testing performed following standardized CLSI broth microdilution methodology (M07). Percent susceptibilities were determined using 2020 CLSI MIC breakpoints. Phenotypic ESBL screening and confirmatory testing were performed using the CLSI M100 method. The in vitro activity of ceftaroline is summarized in the following table. Overall, 100% of MSSA and 93.8% of MRSA from SSSI were susceptible to ceftaroline (MIC ≤1 µg/ml); 6.2% of MRSA isolates were ceftaroline -susceptible dose-dependent (MIC 2-4 µg/ml) with greatest proportion being from Chile (57.1% of 1,669 isolates), Thailand (36.5% of 2,318 isolates), and S. Korea (29.3% of 1,231 isolates). No ceftaroline-resistant MRSA were observed. All S. pyogenes and 88.5% of ESBL-negative Enterobacterales were also susceptible to ceftaroline. Table Ceftaroline continues to demonstrate potent in vitro activity against clinically relevant pathogens associated with SSSIs. Greg Stone, PhD, AztraZeneca (Shareholder, Former Employee)Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor)