In vitro activity of ceftobiprole on 440 Staphylococcus aureus strains isolated from bronchopulmonary infections

Abstract

ObjectiveWe assessed the in vitro activity of ceftobiprole on 440 Staphylococcus aureus clinical strains isolated from bronchopulmonary infections (2010–2014). MethodsS. aureus isolates were characterized for methicillin resistance, PVL status, and clonal complex. All isolates were tested for minimal inhibitory concentrations (MIC) determination by broth microdilution method for ceftobiprole, ceftaroline fosamil, and comparator antibiotics (linezolid, tigecycline, vancomycin, and daptomycin). ResultsA total of 325 (74%) strains were methicillin-susceptible S. aureus (MSSA) and 115 (26%) were methicillin-resistant S. aureus (MRSA); 105 (24%) S. aureus strains were PVL-positive, including 35.2% (37/105) MRSA and 64.8% (68/105) MSSA. Ceftobiprole was highly active against S. aureus with MIC90 of 1 mg/L, MICs ranging between 0.12 and 4mg/L (only one resistant strain, MIC of 4 mg/L). MIC50 and MIC90 were twice lower in MSSA than MRSA. Moreover, PVL+ MRSA were slightly more susceptible to ceftobiprole (MIC50 of 0.5 mg/L and MIC90 of 1 mg/L) than PVL− MRSA (MIC50 and MIC90 of 1 mg/L). The ceftobiprole-resistant strain was also resistant to ceftaroline fosamil and presented the D239L mutation in PBP2A. The comparator antibiotics were equally active on the strains tested, with MIC90 of 0.5 mg/L for ceftaroline fosamil, tigecycline, and daptomycin; 1 mg/L for vancomycin; and 2 mg/L for linezolid. ConclusionsOur results suggest that ceftobiprole is highly active against S. aureus and is an effective alternative to vancomycin or linezolid in the management of staphylococcal pneumonia. However, close monitoring of isolates should be maintained to prevent resistant strain diffusion.