Inhibition of Streptococcus pneumoniae penicillin-binding protein 2x and Actinomadura R39 DD-peptidase activities by ceftaroline

Although the rate of acylation of a penicillin-resistant form of Streptococcus pneumoniae penicillin-binding protein 2x (PBP2x) by ceftaroline is 80-fold lower than that of its penicillin-sensitive counterpart, it remains sufficiently high ( k 2 /K = 12,600 M −1 s −1 ) to explain the sensitivity of the penicillin-resistant strain to this new cephalosporin. Surprisingly, the Actinomadura R39 DD-peptidase is not very sensitive to ceftaroline.