title: In vitro antibacterial activity of gramicidin and tyrothricin.
abstract: 815 recent clinical isolates of different species representing pathogenic or saprophytic constituents of human microbial flora were submitted to agar dilution tests. In concentrations above 64 micrograms/ml tyrothricin is in general equally as gramicidin or slightly more effective whereas below 8 micrograms/ml gramicidin is mostly more effective than tyrothricin. Of 401 streptococci all were inhibited by tyrothricin and gramicidin in concentrations up to 96 micrograms/ml; staphylococci were more resistant. The pathogenic species of 130 strains of gram-negative cocci were more susceptible than the saprophytic species. Haemophilus strains were mostly resistant to gramicidin and to a lesser extent to tyrothricin. Enterobacteriaceae were totally resistant to both antibiotics.
mesh_terms: D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000382:microbiology; D006096:Gramicidin / Q000494:pharmacology*; D006801:Humans; D014449:Tyrothricin / Q000494:pharmacology*
chemical_list: D014449:Tyrothricin; D006096:Gramicidin