Pharmacodynamic Parameters of Gentamicin and their Influence on Surface Hyd-rophobicity of Acinetobacter baumannii

Overview

The postantibiotic effect (PAE) and postantibiotic effect of subinhibitory concentration (PA SME) ofgentamicin as well as influence of these pharmacodynamic parameters on surface hydrophobicityof three Acinetobacter baumannii strains were studied in vitro. Suppression of bacterial growth(PAE) after a short time exposure of bacteria to gentamicin (30 min) at suprainhibitory concentra -tion 2x MIC was in the range of 0.6 h to 3.4 h. Longer PAE was observed after treatment of bacteriawith gentamicin at 4x MIC (1.5 h – 5.1 h). Supra-subinhibitory concentrations of gentamicin (2x or4x MIC + 0.2x MIC) caused still more effective delay of bacterial regrowth (PA SME) in comparisonwith suprainhibitory concentrations for one strain (9.1 h and 9.6 h) and in the case of further twostrains they were so efficient that regrowth of bacteria was not observed for 24 h. Surfacehydrophobicity of the gentamicin treated strains evaluated by adherence of bacteria to xylene rangedfrom 90.0% to 99.7% of the control values (without antibiotic).

Key words:
gentamicin – pharmacodynamic parameters – Acinetobacter baumannii – surfacehydrophobicity