Synergism of trimethoprim and ciprofloxacin in vitro against clinical bacterial isolates

  • P. Huovinen
  • J. S. Wolfson
  • D. C. Hooper


For the first time, the effects of combinations of trimethoprim and a fluoroquinolone (ciprofloxacin) against gram-positive and gram-negative bacterial isolates were evaluated in vitro. Synergism was found in 31 % (fractional inhibitory concentration, FIC) and 33 % (fractional bactericidal concentration, FBC) of 121 clinical isolates of various bacterial strains, most often inEscherichia coli, staphylococci, and enterococci. Antagonism occurred in 1 % (FIC) and 3 % (FBC). The combination of trimethoprim and ciprofloxacin merits further evaluation for potential usefulness as a clinical regimen.


Internal Medicine Bacterial Strain Inhibitory Concentration Clinical Isolate Fluoroquinolone 
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Copyright information

© Friedr. Vieweg & Sohn Venlagsgesellschaft mbH 1992

Authors and Affiliations

  • P. Huovinen
    • 1
    • 2
  • J. S. Wolfson
    • 1
    • 2
    • 3
  • D. C. Hooper
    • 3
  1. 1.Department of Medical MicrobiologyTurku UniversityTurkuFinland
  2. 2.Antimicrobial Research UnitNational Public Health InstituteTurkuFinland
  3. 3.Infectious Disease Unit, Medical ServicesMassachusetts General HospitalBostonUSA

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