Effects of continuous exposure to ciprofloxacin on the outer membrane of P. aeruginosa.

The present work evaluated the effect of ciprofloxacin on the outer membrane proteins (OMPs), lipopolysaccharide (LPS) and the variation of minimal inhibitory concentrations (M.I.C.) of three P. aeruginosa strains after using 1/2 and 1/16 sub-M.I.C. drug doses for five days. Ciprofloxacin significantly modified the M.I.C. values. After contact with sub-M.I.C. drug doses two strains showed a decreased expression of a band migrating at 46 Kd, i.e. in the region of protein D that some authors claim is involved in quinolone diffusion. No major alteration of LPS structure was observed.