Activity of polyhexanide and octenidine against bacterial catheter biofilms. Polyhexanide and octenidine in different concentrations were added once at the beginning of the biofilm formation process to artificial urine containing bacteria and catheter segments (a, c) or biofilms formed on catheter segments in artificial urine were treated with 250 mg/L (E. coli and P. mirabilis) or 500 mg/L (P. aeruginosa) polyhexanide (P) and octenidine (O) for 24 h. Planktonic (c, d) and biofilm-forming bacteria (a, b) were quantified. Open symbols show the values of the individual measurements. Horizontal lines show median values. ctrl, control without adding disinfectants; LOD, limit of detection; nd, not determined. *p < 0.05 over control, **p < 0.01 over control, ***p < 0.001 over control, ****p < 0.0001 over control.