581. In vitro Tedizolid Minimum Inhibitory Concentration (MIC) Against Clinical Isolates of Mycobacterium abscessus.
Session: Poster Abstract Session: TB: Non-Tuberculous Mycobacterial Infections
Thursday, October 8, 2015
Room: Poster Hall
  • IDSA Mab Poster final 10-1-15.pdf (327.0 kB)
  • Background: At MUSC, Mycobacterium abscessusis the second most common etiology of pulmonary mycobacterial infection and is increasingly recognized as an etiology of skin, soft tissue, surgical site, joint and vascular catheter infections. Treatment requires two or three antimicrobials for extended durations; available drug choices are severely limited due to the organism’s inherent resistance. Tedizolid is a novel, potent oxazolidinone pro-drug that interacts with the bacterial 23S ribosome initiation complex to inhibit translation. It is active against all clinically relevant gram-positive pathogens and mycobacteria. Among isolates non susceptible to linezolid, tedizolid MIC are 8- to 16-fold lower than those of linezolid. In this context of extensive antibiotic resistance, further therapeutic options need to be evaluated.

    Methods: We conducted a transversal, descriptive study. The Diagnostic Microbiology Lab collected  M. abscessusclinical isolates during the 2014 calendar year. The MICs for tedizolid and linezolid were determined using Research-use-only broth microdilution panels with Tedizolid and linezolid (0.06-8 µg/mL) from Thermo Scientific Sensititre according to CLSI M24-A2.

    Results: Of 38 isolates tested, 4 were excluded due to either contamination on the purity plate, no growth on the MIC plate, or both. When tedizolid and linezolid MICs were compared, 47% of the isolates were 4-fold more susceptible to tedizolid and 29% were at least 8-fold more susceptible. Fourteen isolates had tedizolid MICs ≤1 µg/mL, 13 had MICs of 2 µg/mL and 4 had MICs of 4 µg/mL. We noted 10 isolates were non-susceptible to linezolid (MIC>8 µg/mL), 7 of these had tedizolid MICs ranging from 2 to 4 µg/mL.

    Conclusion: Our in vitro data suggest tedizolid is likely to be an effective option for treating M. abscessus infections.

    Claudia Taramona-Espinoza, MD1, L.W. Preston Church, MD1 and Lisa Steed, PhD2, (1)Infectious Diseases, Medical University of South Carolina, Charleston, SC, (2)Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC


    C. Taramona-Espinoza, None

    L. W. P. Church, None

    L. Steed, None

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