Influence of growth rate and nutrient limitation on susceptibility of Burkholderia cepacia to ciprofloxacin and tobramycin.

The influence of growth rate and oxygen availability on ciprofloxacin and tobramycin sensitivity and cell surface hydrophobicity in Burkholderia cepacia was assessed for cells grown in a chemostat under iron-limitation. Whereas susceptibility to both antibiotics decreased with increasing growth rate and oxygen repletion yet increased under oxygen depletion, hydrophobicity decreased with increasing growth rate and oxygen repletion but was relatively unaffected under oxygen depletion. These results emphasize the modulating effect of the growth environment on antibiotic susceptibility and the need to perform antimicrobial susceptibility tests under conditions which closely mimic, in vitro, bacterial growth in vivo.