1827. Activity of Omadacycline When Tested Against Gram-positive Bacteria Isolated from Patients in the USA During 2015 as Part of a Global Surveillance Program.
Session: Poster Abstract Session: Antibacterial Susceptibility Surveillance
Saturday, October 29, 2016
Room: Poster Hall
  • IDWeek16 Omadacycline 1827.pdf (580.6 kB)
  • Background: Omadacycline (OMC) is a broad spectrum aminomethylcycline in late stage clinical development for the treatment of acute bacterial skin and skin structure infections and community-acquired pneumonia that is being evaluated as both oral and intravenous, once-daily formulations.

    Methods: A total of 5,102 Gram-positive (GP) organisms isolated during 2015 were selected from medical centers in the USA. Susceptibility testing (S) was performed by reference broth microdilution methods for OMC and comparators.

    Results: OMC was active against Staphylococcus aureus (SA; MIC50/90, 0.12/0.12 µg/ml). The MIC50/90 for methicillin-resistant (MRSA) and MSSA isolates were identical at 0.12/0.12 µg/ml, respectively. All SA were S to tigecycline (TGC; MIC50/90, 0.06/0.12 µg/ml), daptomycin (DAP; MIC50/90, 0.25/0.5 µg/ml), linezolid (LZD; MIC50/90, 1/1 µg/ml), and vancomycin (VAN; MIC50/90, 0.5/1 µg/ml). S was lower in MRSA for levofloxacin (LEV; 29.6%), clindamycin (CLI; 71.2%), and erythromycin (ERY; 10.9/11.6%; CLSI/EUCAST). OMC (MIC50/90, 0.12/0.5 µg/ml) and TGC (MIC50/90, 0.06/0.12 µg/ml) were the most active agents tested against coagulase-negative staphylococci and against Enterococci (both agents MIC50/90, 0.06/0.12 µg/ml). Against Streptococcus pneumoniae (SPN), the MIC50 and MIC90 for OMC (0.06/0.12 µg/ml) and TGC (0.03/0.06 µg/ml), were the lowest among the agents tested. OMC demonstrated activity against ceftriaxone (CRO) and LEV resistant isolates. OMC MIC values for SPN were 8-fold lower than CRO (MIC90, 1 µg/ml) and LEV (MIC90, 1 µg/ml). Against viridans group streptococci, OMC (MIC50/90, 0.06/0.12 µg/ml) and TGC (MIC50/90, 0.03/0.12 µg/ml; 100.0% S) were the most active agents tested. The MIC50/90 for OMC against β-hemolytic streptococci was 0.06/0.12 µg/ml. All β-hemolytic streptococci were S to TGC, β-lactams, LZD, DAP, and VAN, however resistance to LEV (99.5/96.8% S [CLSI/EUCAST]), ERY (65.3% S), CLI (80.7% S) and tetracycline (54.5/54.3% S [CLSI/EUCAST]) occurred.

    Conclusion: OMC was active against a broad range of GP bacteria including MRSA, SPN resistant to penicillin, CRO, and LEV; Enterococci, and streptococci. OMC warrants further study as therapy in infections where these organisms may occur.

    Robert K. Flamm, Ph.D., Rodrigo E. Mendes, PhD, Michael D. Huband, BS and Helio S. Sader, MD, PhD, JMI Laboratories, Inc., North Liberty, IA


    R. K. Flamm, Paratek Pharma, LLC: Research Contractor , Research grant

    R. E. Mendes, Paratek Pharma, LLC: Research Contractor , Research grant

    M. D. Huband, Paratek Pharma, LLC: Research Contractor , Research grant

    H. S. Sader, Paratek Pharma, LLC: Research Contractor , Research grant

    Findings in the abstracts are embargoed until 12:01 a.m. CDT, Wednesday Oct. 26th with the exception of research findings presented at the IDWeek press conferences.