The effect of ofloxacin, pefloxacin and tobramycin at subinhibitory concentrations (1/4, 1/8 and 1/16 of the MICs) on surface hydrophobicity of the Klebsiella pneumoniae strain was studied. The antibiotics tested decreased cell surface hydrophobicity in a dose-dependent manner. The most significant reduction of surface hydrophobicity was found after treatment with antibiotics at 1/4 of their MICs. Surface hydrophobicity of K. pneumoniae after exposure to these concentrations was decreased to 44% (ofloxacin), 50.7% (pefloxacin) and 56.1% (tobramycin) compared with controls.

        Key words: Klebsiella pneumoniae – cell surface hydrophobicity – ofloxacin – pefloxacin – tobramy- cin – subinhibitory concentrations.