Comparison of the in vivo efficacy of ceftaroline fosamil, vancomycin and daptomycin in a murine model of methicillin-resistant Staphylococcus aureus bacteraemia.

The need for alternative drugs to treat methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia has led to a focus on ceftaroline, for which clinical data remain scarce. Herein, the efficacy of ceftaroline fosamil for the treatment of experimental MRSA bacteraemia was compared with that of approved therapies. Five MRSA strains were tested in an immunocompetent BALB/c bacteraemia model. Serum pharmacokinetics of ceftaroline fosamil were determined using HPLC/MS Q-TOF. Two hours after infection with the MRSA strains, mice were administered 50 mg/kg of ceftaroline fosamil every 6 h, for 24 h. This regimen yielded a T>MIC of 61.5% for an MIC of 1 mg/L and proved efficacious against all strains, including an hVISA strain with non-susceptibility to daptomycin, as indicated by the reduction (mean ± s.d.) in log CFU/mL in blood of 2.34 ± 0.33 and log CFU/g in kidney of 2.08 ± 0.22. Similarly, treatment with daptomycin yielded a log reduction of 2.30 ± 0.60 in blood and 2.14 ± 0.31 in kidney. The decrease in bacterial density was less accentuated after treatment with vancomycin, which yielded 1.84 ± 0.73 and 1.95 ± 0.32 log reductions in blood and kidney, respectively. The results of the study showed that the efficacy of ceftaroline fosamil against MRSA bacteraemia in mice is not inferior to that of vancomycin and daptomycin, and indicated the potential use of ceftaroline fosamil against difficult-to-treat S. aureus bacteraemia. Considering these promising data, clinical trials should be conducted to ascertain the efficacy of the drug for treating bloodstream infections in humans.