In Vitro activity of ceftobiprole against 20,255 recent clinical bacterial isolates in Canada (CANWARD 2015-2023).

Background: Ceftobiprole is a fifth-generation cephalosporin active against methicillin-resistant Staphylococcus aureus (MRSA). In this study, we determined the in vitro activities of ceftobiprole and comparator agents against 20,225 common Gram-positive and Gram-negative bacteria isolated from patients who presented for care at 16 tertiary-care hospitals across Canada between 2015 and 2023.

Methods: Minimum inhibitory concentrations (MICs) were determined using the Clinical and Laboratory Standards Institute (CLSI) reference M07 broth microdilution method. MICs were interpreted using CLSI M100 breakpoints where available. As CLSI does not publish MIC breakpoints for ceftobiprole, ceftobiprole MICs were interpreted using United States Food and Drug Administration (FDA), European Committee on Antimicrobial Susceptibility Testing (EUCAST), and Health Canada breakpoints.

Results: Ceftobiprole inhibited 100 % of MRSA at ≤ 4 μg/ml; 100 % of methicillin-susceptible S. aureus (MSSA) and 99.8% of MRSA at ≤ 2 μg/ml; 100 % of Streptococcus pneumoniae and Streptococcus pyogenes at ≤ 0.5 μg/ml; and 97.9 % of ESBL-negative Escherichia coli, 97.4 % of ESBL-negative Klebsiella pneumoniae, 97.8 % of Proteus mirabilis, 89.3 % of Serratia marcescens, 78.2 % of Enterobacter cloacae, 55.7 % of Klebsiella oxytoca at ≤ 0.25 μg/ml. Ceftobiprole was inactive against ESBL-positive E. coli and ESBL-positive K. pneumoniae.

Conclusions: Ceftobiprole demonstrated potent in vitro activity against MRSA, MSSA, S. pneumoniae, S. pyogenes, ESBL-negative E. coli and K. pneumoniae, and P. mirabilis isolated from clinical specimens of patients seeking care at Canadian tertiary-care hospitals.