Antimicrobial Activity of Ceftaroline and Comparator Agents Against Ceftriaxone-Nonsusceptible Streptococcus pneumoniae from the United States (2008–2020)

We evaluated the activity of ceftaroline against clinical isolates of ceftriaxone-nonsusceptible Streptococcus pneumoniae from United States medical centers. Streptococcus pneumoniae isolates ( n = 21,750) were consecutively collected from 201 medical centers in 2008–2020 and tested for susceptibility by broth microdilution method. Among these isolates, 1,419 (6.5%) were ceftriaxone-nonsusceptible (ceftriaxone minimum inhibitory concentration [MIC], ≥2 mg/L). Other resistant subgroups analyzed included multidrug-resistant (MDR; nonsusceptibility to ≥3 classes of agents; n = 4,454) and extensively drug-resistant (XDR; nonsusceptibility to ≥5 classes; n = 1,708) isolates. Ceftriaxone susceptibility increased from 89.0% (2008–2011) to 98.1% (2018–2020). Ceftaroline was active against 99.9% of ceftriaxone-nonsusceptible isolates (MIC 50/90 , 0.25/0.25 mg/L) and retained potent activity against MDR ( n = 4,454; MIC 50/90 , 0.12/0.25 mg/L; >99.9% susceptible) and XDR ( n = 1,708; MIC 50/90 , 0.25/0.25 mg/L; 100.0% susceptible) isolates. Only one isolate had a ceftaroline MIC ≥0.5 mg/L. In summary, ceftaroline demonstrated potent and consistent activity over time (2008–2020) against a large collection of S. pneumoniae from U.S. medical centers, including ceftriaxone-nonsusceptible, MDR, and XDR isolates