Preventing microbial colonisation of catheters: Antimicrobial and antibiofilm activities of cellobiose dehydrogenase

The ability of cellobiose dehydrogenase (CDH) to produce hydrogen peroxide (H2O2) for antimicrobial and antibiofilm functionalisation of urinary catheters was investigated. A recombinantly produced CDH from Myriococcum thermophilum was shown to completely inhibit the growth of Escherichia coli and Staphylococcus aureus both in liquid and solid media when supplemented with either 0.8 mM or 2 mM cellobiose as substrate. Biofilm formation on silicone films was prevented by CDH when supplemented with 1 mM cellobiose. The CDH/cellobiose system also successfully inhibited many common urinary catheter-colonising micro-organisms, including multidrug-resistant S. aureus, Staphylococcus epidermidis, Proteus mirabilis, Stenotrophomonas maltophilia, Acinetobacter baumannii and Pseudomonas aeruginosa. Interestingly, CDH was also able to produce H2O2 during oxidation of extracellular polysaccharides (exPS) formed by micro-organisms in the absence of cellobiose. The H2O2 production and consequently antimicrobial and antibiofilm activities on these exPS were enhanced by incorporation of glycoside hydrolases such as amylases. Hydrolysis of polysaccharides by these enzymes increases the number of terminal reducing sugars as substrates for CDH as well as destabilises the biofilm. Furthermore, CDH suspended in catheter lubricants killed bacteria in biofilms colonising catheters. Incorporation of the CDH/cellobiose system in the lubricant therefore makes it an easy strategy for preventing microbial colonisation of catheters.