The bactericidal activity of the novel beta-defensin hBD-3 against 28 species and 55 strains of gram-positive cocci and gram-negative fermentative and nonfermentative rods was tested. All strains proved to be highly or intermediately susceptible to hBD-3 (minimal bactericidal concentration [MBC], </=50 micro g/ml), except for Burkholderia cepacia, for all 23 tested strains of which MBCs were >100 micro g/ml.