Control of pathogen growth and biofilm formation using a urinary catheter that releases antimicrobial nitrogen oxides

Antibacterial nitrogen oxides including nitric oxide are formed from nitrite under acidic conditions. In a continuous-flow model of the urinary bladder we used the retention cuff of an all-silicone Foley catheter as a depot for export of nitrogen oxides. The cuff was filled with sodium nitrite (50mM) and an acidic buffer solution (pH 3.6) and the growth of nine common uropathogens in the surrounding artificial urine was measured along with biofilm formation on the catheter surface. In experiments with control catheters (NaCl) bacteria grew readily and biofilm developed within hours in five of nine strains. In contrast, with test catheters bacterial counts were markedly reduced and biofilm formation by Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterobacter cloace was prevented, whereas Escherichia coli and Staphylococcus aureus were unaffected. We conclude that antibacterial nitrogen oxides generated in the retention cuff of a urinary catheter diffuse into urine and prevent the growth of urinary pathogens and biofilm formation. Although promising, future studies will reveal if this novel approach can be clinically useful for the prevention of catheter-associated urinary tract infections.