Susceptibility of clinical isolates of methicillin-resistant Staphylococcus aureus and phenotypic non-extended-spectrum β-lactamase-producing Klebsiella pneumoniae to ceftaroline in Taiwan: Results from the Antimicrobial Testing Leadership and Surveillance (ATLAS) in 2012–2018 and Surveillance of Multicentre Antimicrobial Resistance in Taiwan (SMART) in 2018–2019

ABSTRACT Data of ceftaroline (CPT) susceptibility amongst clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA, n=1,284) and phenotypic non-extended-spectrum β-lactamase-producing (non-ESBL-P) Klebsiella pneumoniae (n=466), obtained from the Antimicrobial Testing Leadership and Surveillance (ATLAS) from 2012–2018, and selected MRSA isolates from patients with bloodstream infection (BSI) (n=95) from the Surveillance of Multicentre Antimicrobial Resistance in Taiwan (SMART) from 2018–2019 were analysed. The minimum inhibitory concentrations (MICs) of ATLAS isolates were determined using the broth microdilution method, whereas MICs of SMART BSI-MRSA isolates were determined using the Etest and MicroScan system. The pharmacokinetic profiles and pharmacodynamic parameters of CPT were applied to explore the optimal dosage against infections caused by Taiwanese MRSA and K. pneumoniae isolates. Approximately 7.1% of ATLAS-MRSA were susceptible-dose dependent (S-DD) to CPT, and 19.7% of the non-ESBL-P K. pneumoniae isolates were not susceptible to CPT. Amongst the ATLAS-MRSA isolates, the S-DD rates to CPT amongst isolates causing lower respiratory tract infections were 11.9% and 8.5% cultured at intensive care units (ICUs) and general wards (GWs), and those causing skin and soft-tissue infections (SSTI) were 20%/5.3% from ICUs/GWs (P=0.015), respectively. 22.7% of the SSTI-MRSA isolates from GWs displayed vancomycin MICs of >1 mg/L. Amongst 95 SMART BSI-MRSA isolates, 28 (46.7%) isolates exhibited lower CPT-MICs by the Etest compared to 60 isolates with CPT-MIC of 1-2 mg/L by MicroScan system. A CPT dosage of 600 mg as a 2-h intravenous infusion every 8 h is suggested for treatment of infections caused by MRSA and phenotypic non-ESBL-P K. pneumoniae in Taiwan.