Tedizolid Activity Against Clinical Complex Isolates-An Characterization Study.

complex consist of three rapidly growing subspecies: , and . They are clinically important human pathogens responsible for opportunistic pulmonary and skin and soft tissue infections. Treatment of infections is difficult due to resistance to most antimicrobial agents. Tedizolid (TZD) is a next-generation oxazolidinone antimicrobial with a wide spectrum of activity even against multidrug resistant Gram-positive bacteria. In this study, the activity of TZD against the complex ( = 130) was investigated. Susceptibility testing by broth microdilution showed lower TZD minimum inhibitory concentrations (MICs) when compared to linezolid. The MIC and MIC was 1 mg/L and 4 mg/L, respectively across all complex members, reflecting no difference in subspecies response to TZD. Pre-exposure of complex to subinhibitory concentrations of TZD did not trigger any inducible drug resistance. Single-drug time kill assays and bactericidal activity assays demonstrated bacteriostatic activity of TZD in all three subspecies, even at high drug concentrations of 4 to 8x MIC. Combination testing of TZD with clarithromycin, doxycycline and amikacin using the checkerboard approach showed no antagonistic interactions. TZD may be an effective therapeutic antimicrobial agent for the treatment of infections.