Background: Ceftaroline (CPT), the active metabolite of the prodrug CPT fosamil, is a cephalosporin with potent in vitro activity against methicillin-resistant S. aureus (MRSA). CPT fosamil was approved by the USA-FDA in 2010 for treatment of acute bacterial SSSI, including those caused by MRSA, and of community-acquired bacterial pneumonia.
Methods: Among 16,413 organisms consecutively collected from patients with bacteremia in the AWARE CPT surveillance program (2008-2014), 1,380 (8.4%) were from cases where SSSI was reported as the primary site of infection. These organisms were collected in 24 medical centers in the USA and tested for susceptibility (S) against CPT and comparators by the broth microdilution method.
Results: The most common organisms isolated from bacteremia associated with SSSI were S. aureus (670; 48.6%), E. coli (200; 14.5%), β-hemolytic streptococci (BHS; 138; 10.0%) and K. pneumoniae (KPN; 109; 7.9%). MIC90 and %S are summarized in the Table. Among S. aureus, 50.6% of isolates were MRSA, and CPT was very active against both methicillin-S S. aureus (MSSA; MIC50/90, 0.25/0.25 µg/mL; highest MIC, 0.5 μg/mL; 100.0% S) and MRSA (MIC50/90, 1/1 µg/mL; 95.9% S; highest MIC, 2 μg/mL). Against MSSA, CPT was 16-, 4- and 4- to 8-fold more active than ceftriaxone, vancomycin and linezolid, respectively. Among MSSA, S rates to clindamycin (CLI) and levofloxacin (LEV), were 94.9 and 87.6%, respectively. For MRSA, 95.9% and 100.0% of strains were inhibited at ≤1 and ≤2 μg/mL of CPT, respectively; all other β-lactams exhibited very limited activity against these organisms. 29.5 and 67.8% of MRSA were resistant to CLI and LEV, respectively. ESBL phenotype was observed among 13.0 and 10.1% of EC and KPN, respectively.
Conclusion: CPT and tigecycline provided the best in vitro overall coverage against organisms causing bacteremia in patients with SSSI.
H. S. Sader,
R. E. Mendes, Actavis: Research Contractor , Research support
D. J. Farrell, Actavis: Research Contractor , Research support
R. N. Jones, Actavis: Research Contractor , Research support
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