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Results of the Surveillance of Tedizolid Activity and Resistance (STAR) Program: In Vitro Susceptibility of Gram-Positive Clinical Isolates Collected in 2013 From the United States

Abstract

Background.  Tedizolid is a novel oxazolidinone antibacterial with potent activity against a wide range of Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), a key pathogen associated with acute bacterial skin and skin structure infections (ABSSSI). As part of the Surveillance of Tedizolid Activity and Resistance (STAR) Program, the in vitro activity of tedizolid was analyzed against a variety of clinically relevant Gram-positive pathogens isolated from clinical sources in 2013. Methods.  Nonduplicate, nonconsecutive, single-patient clinical isolates of key Gram-positive pathogens (N = 1473) were collected from 36 clinical centers in the United States in 2013. Isolates underwent susceptibility testing against tedizolid in accordance with CLSI M7 and M100 guidelines at a central laboratory (Eurofins, Chantilly, VA). Results.  Tedizolid MIC values were determined for S. aureus (n = 1088), CoNS (n = 110), and enterococci (n = 275) from various infection/lesion sites. Tedizolid was active against all of these pathogen groups, with MIC90 values of 0.5 µg/mL for MRSA and MSSA; 0.25 µg/mL for CoNS; and 0.5 µg/mL for enterococci. Pathogen Isolates (n) Tedizolid MIC (µg/mL) Range Mode MIC50 MIC90 All S. aureus 1088 ≤0.03-1.0 0.25 0.25 0.5 MRSA 499 ≤0.03-1.0 0.25 0.25 0.5 MSSA 589 ≤0.03-1.0 0.25 0.25 0.5 CoNS 110 ≤0.03-0.5 0.12 0.12 0.25 Enterococcus spp 275 0.06-2.0 0.25 0.25 0.5 MIC50 = 50% minimum inhibitory concentration; MIC90 = 90% minimum inhibitory concentration Conclusion.  Based on MIC90 values, tedizolid retains potent activity against Gram-positive pathogens implicated in ABSSSI, including MRSA. The results obtained in this analysis are consistent with the findings obtained in tedizolid surveillance studies conducted in prior years. The serious public health problem of antibacterial resistance warrants continued surveillance of tedizolid activity. Disclosures.   P. Bien, Cubist: Employee, Salary P. Prokocimer, Cubist: Employee and Shareholder, Salary