In-vitro profile of a new β-lactam, ceftobiprole, with activity against methicillin-resistant Staphylococcus aureus

Ceftobiprole is a novel, broad-spectrum cephalosporin with in-vitro activity against common Gram-positive and Gram-negative organisms. It forms a stable inhibitory complex with Staphylococcus aureus penicillin-binding protein (PBP) 2' (2a), resulting in enhanced activity against methicillin-resistant S. aureus (MRSA). In recent studies of methicillin-susceptible S. aureus, the ceftobiprole MIC90 value was most frequently <= 1.0 mg/L (MIC range <= 0.25-1.0 mg/L). For MRSA, MIC90 values were generally 2.0 mg/L (MIC range <= 0.06-4.0 mg/L). MICs for all streptococcal species, except penicillin-resistant Streptococcus viridans but including penicillin-resistant Streptococcus pneumoniae, ranged from <= 0.008 to 2.0 mg/L. Ceftobiprole is active against Enterococcus faecalis (MIC90 = 4 mg/L), but not generally active against Enterococcus faecium (MIC90 > 16 mg/L). Ceftobiprole displayed bactericidal activity against Gram-negative pathogens comparable to that of cefepime, ceftazidime or piperacillin-tazobactam in early studies. However, recent data show activity against Pseudomonas aeruginosa similar to that of cefepime but less than that of ceftazidime. Ceftobiprole, like cefepime, is stable in the presence of most class A non-extended spectrum beta-lactamases and inducible class C beta-lactamases. Ceftobiprole is a poor inducer of AmpC beta-lactamase and a poor substrate for hydrolysis by AmpC beta-lactamase. Studies of ceftobiprole in several animal models have demonstrated potent in-vivo efficacy against infections caused by MRSA, including strains intermediately resistant to vancomycin. It was also efficacious in murine infections caused by Gram-negative bacteria with MIC values <= 2 mg/L. The broad spectrum of activity demonstrated by ceftobiprole in vitro and in vivo suggests that it may have potential for empirical treatment of suspected Gram-negative and Gram-positive infections, including those caused by MRSA.