Antimicrobial activity of ceftobiprole against Gram-negative and Gram-positive pathogens: results from INVITA-A-CEFTO Brazilian study

ABSTRACT

Ceftobiprole is a broad-spectrum cephalosporin with potent activity against staphylococci, including those resistant to oxacillin, as well as against most Gram-negative bacilli including Pseudomonas aeruginosa. In this study, the in vitro activity of ceftobiprole and comparator agents was tested against bacterial isolates recently collected from Brazilian private hospitals. A total of 336 unique bacterial isolates were collected from hospitalized patients between February 2008 and August 2009. Each hospital was asked to submit 100 single bacterial isolates responsible for causing blood, lower respiratory tract or skin and soft tissue infections. Bacterial identification was confirmed and antimicrobial susceptibility testing was performed using CLSI microdilution method at a central laboratory. The CLSI M100-S21 (2011) was used for interpretation of the antimicrobial susceptibility results. Among the 336 pathogens collected, 255 (75.9 percent) were Gram-negative bacilli and 81 (24.1 percent) were Gram-positive cocci. Although ceftobiprole MIC50 values for oxacillin resistant strains were two-fold higher than for methicillin susceptible S. aureus, ceftobiprole inhibited 100 percent of tested S. aureus at MICs < 4 µg/mL. Polymyxin B was the only agent to show potent activity against Acinetobacter spp. (MIC50/90, 0.5/1 µg/mL), and P. aeruginosa (MIC50/90, 1/2 µg/mL). Resistance to broad-spectrum cephalosporins varied from 55.3-68.5 percent and 14.3-28.5 percent among E. coli and Klebsiella spp. isolates, respectively; with ceftobiprole MIC50 > 6 µg/mL for both species. Our results showed that ceftobiprole has potent activity against staphylococci and E. faecalis, which was superior to that of vancomycin. Our data also indicates that ceftobiprole demonstrated potency comparable to that of cefepime and ceftazidime against key Gram-negative species.