In vitro activity of loracarbef against common respiratory pathogens compared with amoxicillin-clavulanic acid: a multi-centre study in The Netherlands.

Abstract Loracarbef (LC) is the first clinically available carbacephem. In order to evaluate the antimicrobial activity of LC, a total of 593 clinical strains of H. influenzae, M. catarrhalis, S. pneumoniae and S. pyogenes were collected by seven participating study centres. Minimal inhibitory concentrations for loracarbef and amoxycillin-clavulanic acid combination (AC) were determined by a microdilution method. The MIC-90 of β-lactamase-negative strains of H. influenzae was 2.0 (LC) and 0.5 (AC), and for β-lactamase-positive strains 4.0 (LC) and 2.0 (AC) mg/l. For β-lactamase-negative and β-lactamase-positive strains of M. catarrhalis , the MIC-90 results were 0.5 and 2.0 (LC) and 0.13 and 0.5 (AC) mg/l. The MIC-90 for AC was ≤0.03 for both S. pneumoniae and S. pyogenes , while the LC results were 0.5 and 0.25 mg/l, respectively. Of all strains tested, only one β-lactamase-positive isolate of H. influenzae was shown to be resistant to LC and another one to be resistant to AC. The MICs for both AC and LC were significantly higher in H. influenzae and M. catarrhalis strains isolated in the centre and in the south-east of The Netherlands. In conclusion, the results of this study indicate that loracarbef can be used in the initial therapy of community acquired respiratory infections.