The effects of photoactivated ciprofloxacin and bile acids on biofilms on bile duct catheters.

ABSTRACT

OBJECTIVES: This study examined the potential of a novel photoactivatable ciprofloxacin to act against bacterial infections and microbiomes related to biliary diseases. It also evaluated treatment by combining the impact of bile acids and antibiotics on biofilms. Innovative strategies were evaluated to address the elusive bile duct microbiome resulting in biofilm-related infections linked to biliary catheters. The healthy biliary system is considered sterile, but bile microbiomes can occur in disease, and these correlate with hepatobiliary diseases. Causes include biofilms that form on internal-external biliary drainage catheters. These biliary catheters were used to noninvasively study the otherwise elusive bile microbiome for a pilot study. METHODS: A new photoactivatable antibiotic was tested for efficacy against human-derived pathogenic bacterial isolates - Salmonella enterica and Escherichia coli - and catheter-derived bile duct microbiomes. In addition, the effect of bile acids on the antibiotic treatment of biofilms was quantified using crystal violet staining, confocal laser scanning microscopy, and biofilm image analysis. Two novel approaches for targeting biliary biofilms were tested. RESULTS: A photoactivated antibiotic based on ciprofloxacin showed efficacy in preventing biofilm formation and reducing bacterial viability without harming eukaryotic cells. Furthermore, combination treatment of antibiotics with bile acids, such as ursodesoxycholic acid, mildly influenced biofilm biomass but reduced bacterial survival within biofilms. CONCLUSION: Bile acids, in addition to their endocrine and paracrine functions, may enhance antibiotic killing of bacterial biofilms compared with antibiotics alone. These approaches hold promise for treating biliary infections such as cholangitis.