Comparison of in vitro inhibitory and bactericidal activities of daptomycin (LY 146032) and four reference antibiotics, singly and in combination, against gentamicin-susceptible and high-level-gentamicin-resistant enterococci

Chemotherapy. Sep-Oct 1993;39(5):302-9. doi: 10.1159/000239141.


The in vitro inhibitory and bactericidal activities of daptomycin and reference antibiotics were determined by serial macrobroth dilution for 23 gentamicin-susceptible (MIC: < 2,000 mg/l) and 21 high-level-gentamicin-resistant (HLGR) Enterococcus faecalis, Enterococcus faecium, and Enterococcus avium isolates. The activities of daptomycin, vancomycin, and teicoplanin were independent of the gentamicin susceptibility profile and species tested. For all the isolates, the inhibitory activity of daptomycin (MIC90: 2 mg/l) was comparable to vancomycin (MIC90: 2 mg/l), but less than that of teicoplanin (MIC90: 0.5 mg/l). Daptomycin demonstrated excellent bactericidal activity against all enterococci tested (MBC90: 8 mg/l). In contrast, all microorganisms were tolerant to vancomycin and teicoplanin. Ampicillin and ciprofloxacin MICs and MBCs were dependent on enterococcal gentamicin resistance profile and species, with MICs and MBCs that ranged between 1 and > 64 mg/l. By time-kill curves, the combination of daptomycin plus ampicillin demonstrated synergistic bactericidal activity against gentamicin-susceptible and HLGR E. faecalis. Daptomycin, singly and in combination, may be useful in treating enterococcal infections, including those caused by HLGR microorganisms.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Ampicillin / pharmacology
  • Anti-Bacterial Agents / pharmacology*
  • Ciprofloxacin / pharmacology
  • Daptomycin
  • Drug Combinations
  • Drug Resistance, Microbial
  • Enterococcus / drug effects*
  • Enterococcus faecalis / drug effects*
  • Enterococcus faecium / drug effects*
  • Gentamicins / pharmacology
  • Humans
  • Microbial Sensitivity Tests
  • Peptides / pharmacology
  • Teicoplanin / pharmacology


  • Anti-Bacterial Agents
  • Drug Combinations
  • Gentamicins
  • Peptides
  • Ciprofloxacin
  • Teicoplanin
  • Ampicillin
  • Daptomycin