Sensitivity to Bactericidal Activity of Serum and Surface Hydrophobi-city of Acinetobacter baumannii after Treatment with Imipenem

Overview

Sensitivity to the serum bactericidal activity and surface hydrophobicity of Acinetobacter bauman-nii strains isolated from the urinary (UT) or respiratory tract (RT) of patients after exposure toimipenem at subinhibitory concentrations (sub-MICs) (1/4, 1/8 or 1/16 of their MICs) were tested. Theantibiotic at the mentioned concentrations decreased significantly the sensitivity of strain UT tothe bactericidal activity of human serum. Sensitivity to the bactericidal activity of serum of strainRT was affected only very ineffectively. Imipenem at 1/4 of their MICs reduced the cell surfacehydrophobicity to 76.1% (strain UT) and to 81.9% (strain RT) compared with control values (withoutimipenem). Lower concentrations of antibiotic influenced cell surface hydrophobicity only toa smaller extent. Possible decrease in sensitivity of bacteria to the bactericidal activity of serumafter treatment with imipenem in „in vivo“ experiments would manifest an increase in virulence ofthese strains.

Key words:
Acinetobacter baumannii – sensitivity to bactericidal activity of serum – surfacehydrophobicity – imipenem – subinhibitory concentrations.