The impact of a cation channel blocker (furosemide) on Pseudomonas aeruginosa PAO1 biofilm architecture

OBJECTIVE: To determine if furosemide could have a role in inhibition of biofilm formation. STUDY DESIGN: A prospective study of 72-hour biofilms grown in the Calgary Biofilm Device (CBD) treated with furosemide and controls. METHODS: Bacteria were treated with furosemide and controls to determine its antiplanktonic properties. PA01 biofilms were treated with serial 2-fold dilutions of furosemide and controls over a 48-hour period at pH concentrations of 7.0, 8.0, and 9.0. RESULTS: Furosemide had no effect on planktonic PA01. It had minimal effect at pH below 8.0. A pH of 8.0 and 9.0 reduced biofilms 25%. Furosemide 10 mg/mL reduced biofilms 50% at pH 8.0 and 9.0. Tt inhibited biofilms to <30% at concentrations of 0.6 to 0.16 mg/mL at pH 8.0 and < 10% at concentrations of 1.25 to 0.3 mg/mL at pH 9.0. CONCLUSION: Furosemide was found to be nonantiplanktonic, but does appear to destabilize preformed PAO] biofilms at pl-l-dependent concentrations. (C) 2007 American Academy of Otolaryngology-Head and Neck Surgery Foundation. All rights reserved.