Salicylate induction of phenotypic resistance to quinolones in Serratia marcescens

The influence of salicylic acid on the permeability and susceptibility of S erratia marcescens to both nalidixic acid and ciprofloxacin was studied, as well as the effect of salicylate on outer membrane proteins and lipopolysa ccharide. As salicylic acid concentration increased, ciprofloxacin accumula tion decreased with a concomitant, previously observed, reduction in the po rin content of the outer membrane. Resistance to ciprofloxacin and nalidixi c acid was enhanced when bacteria grew in the presence of salicylic acid.