Ceftobiprole medocaril is a newly approved drug in Europe for the treatment of hospital-acquired pneumonia (HAP) (excluding patients with ventilator-associated pneumonia but including ventilated HAP patients) and community-acquired pneumonia in adults. The aim of this study was to evaluate the in vitro antimicrobial activity of ceftobiprole against prevalent Gram-positive and -negative pathogens isolated in Europe, Turkey, and Israel during 2005 through 2010. A total of 60,084 consecutive, nonduplicate isolates from a wide variety of infections were collected from 33 medical centers. Species identification was confirmed, and all isolates were susceptibility tested using reference broth microdilution methods. Ceftobiprole had high activity against methicillin-susceptible Staphylococcus aureus (MSSA) (100.0% susceptible), methicillin-susceptible coagulase-negative staphylococci (CoNS), beta-hemolytic streptococci, and Streptococcus pneumoniae (99.3% susceptible), with MIC 90 values of 0.25, 0.12, <0.06, and 0.5 g/ml, respectively. Ceftobiprole was active against methicillin-resistant S. aureus (MRSA) (98.3% susceptible) and methicillin-resistant CoNS, having a MIC 90 of 2 g/ml. Ceftobiprole was active against Enterococcus faecalis (MIC 50/90 , 0.5/4 g/ml) but not against most Enterococcus faecium isolates. Ceftobiprole was very potent against the majority of Enterobacteriaceae (87.3% susceptible), with >80% inhibited at <0.12 g/ml. The potency of ceftobiprole against Pseudomonas aeruginosa (MIC 50/90 , 2/>8 g/ml; 64.6% at MIC values of <4 g/ml) was similar to that of ceftazidime (MIC 50/90 , 2/>16 g/ml; 75.4% susceptible), but limited activity was observed against Acinetobacter spp. and Stenotrophomonas maltophilia. High activity was also observed against all Haemophilus influenzae (MIC 90 , <0.06 g/ml) and Moraxella catarrhalis (MIC 50/90 , <0.06/0.25 g/ml) isolates. Ceftobiprole demonstrated a wide spectrum of antimicrobial activity against this very large longitudinal sample of contemporary pathogens. C eftobiprole medocaril (BAL5788, formerly Ro-65-5788) is the prodrug form of ceftobiprole (BAL9141, formerly Ro-63-9141), which is an extended-spectrum anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) parenteral cephalosporin with potent activity against Gram-positive and -negative bacterial pathogens. Ceftobiprole has been evaluated in several phase III clinical trials focusing on skin and skin structure infections (SSSI) (1, 2), community-acquired pneumonia (CAP) requiring hospitalization (3), and hospital-acquired pneumonia (HAP), including ventilator-associated pneumonia (VAP) (4), and has recently obtained regulatory approval in Europe for the treatment of hospital-acquired pneumonia (excluding ventilator-associated pneumonia) and community-acquired pneumonia in adults. Ceftobiprole is relatively stable toward AmpC -lactamases and has a strong affinity for penicillin binding proteins (PBPs), including PBP 2A, which mediates resistance to -lactams in MRSA and methicillin (oxacillin)-resistant co...