Activities of ceftobiprole and other β-lactams against Streptococcus pneumoniae clinical isolates from the United States with defined substitutions in penicillin-binding proteins PBP 1a, PBP 2b, and PBP 2x

The activities of ceftobiprole and other beta-lactams were examined with 30 Streptococcus pneumoniae isolates containing multiple pbp1a, p1p2b, and pbp2x mutations. The highest ceftobiprole MIC was 1 mu g/ml, while the comparator MICs were 16 to 64 mu g/ml. Fifty percent inhibitory concentrations for penicillin-binding protein 2x were 0.5 mu g/ml (ceftobiprole) and 4 mu g/ml (ceftriaxone) in a penicillin- and ceftriaxone-resistant isolate.