Methods: 349 methicillin-sensitive and –resistant S. aureus (MSSA and MRSA, respectively) isolates were collected from various infection sources at multiple hospitals from 2015-2017 throughout the US, Greece, Hungary and Italy. In addition to the contemporary isolates, a set of 149 MSSA and MRSA clinical isolates from 2011 were also obtained from US hospital sources. MICs for CF-301 were determined using a new antimicrobial susceptibility testing (AST) medium for broth microdilution recently endorsed by Clinical and Laboratory Standards Institute (CLSI) for use with CF-301. The testing medium consists of cation-adjusted Muller Hinton Broth supplemented with 25% horse serum and 0.5 mM DTT (CAMHB-HSD). Susceptibility to conventional antibiotics was also examined in this study using standard methodology (CLSI document M07-A10) and included: vancomycin, trimethoprim-sulfamethoxazole, daptomycin, oxacillin, linezolid, clindamycin, and cefazolin.
Results: CF-301 had MIC50, MIC90, and MIC100 values of 0.5, 1, and 2 μg/mL, respectively, against each set of contemporary MSSA (n=176) and MRSA (n=173) clinical isolates. There were no differences noted with respect to the geographic source (in the US and Europe) of isolates. Furthermore, the CF-301 MICs reported here for 2015-2017 isolates were identical to that observed for MSSA and MRSA isolates from 2011.
Conclusion: CF-301 demonstrated potent in vitro activity against a total of 498 clinical S. aureus isolates from a range of human infections (including bacteremia) and different geographies. Contemporary clinical isolates did not demonstrate reduced susceptibility to CF-301 compared to the 2011 isolates.
R. Schuch, ContraFect Corp: Employee , Salary
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