139 OligoG fluorescent conjugation for localisation in a mucoid pseudomonal biofilm

Abstract

Objectives Mucoid pseudomonal biofilms in the cystic fibrosis (CF) lung represent an important clinical challenge in the treatment of respiratory infections leading to antibiotic resistance and high mortality. OligoG is an alginate oligosaccharide that potentiates the effect of antibiotics against multi-drug resistant bacteria. It has previously been shown to disrupt the formation of pseudomonal biofilms and alter the cell wall surface charge of planktonic bacteria. This study evaluated the anti-biofilm properties of OligoG by analysing its ability to penetrate the biofilm of a mucoid CF isolate Pseudomonas aeruginosa (NH53788A). Methods OligoG was conjugated to the fluorophore Texas-Red (TxRd) cadaverine. SYTO-9® confocal laser microscopy was employed to study the disruption of biofilm formation when treated with TxRd-labelled OligoG, as well as its anti-biofilm properties on 24 h established biofilms. Controls to test for inherent anti-biofilm properties of TxRd and possible dissociation of the conjugate were also performed. Results Dose-dependent effects on NH53788A biofilm formation were evident when treated with TxRd-labelled OligoG, as observed by inhibition of growth, as well as disruption of established biofilms. TxRd-labelled OligoG was able to penetrate the entire biofilm depth. No biofilm disruption or dissociation of the conjugate occurred using TxRd alone. COMSTAT® analysis revealed a significant decrease in biofilm volume/height with increase in OligoG dose (0.5–6%; p Conclusion These studies support previously reported inhibition and disruption properties of OligoG and provide insight into the mechanistic action of OligoG in biofilm disruption.