Although in health bile duct are considered sterile, in disease, the occurrence and progression of bile microbiomes are reported. This is correlated to hepatobiliary diseases like cholangitis. The establishment of a bile microbiome often occurs after liver or pancreatic surgery. The biofilms on internal-external biliary drainage catheters or biliary catheters can be used to study noninvasively the otherwise elusive bile microbiome. Biliary catheters, although they are initially sterile, often become overgrown with bacterial biofilms, suspected to originate from the gut microbiota. Bacteria in biofilms present often a high phenotypic resistance to antibiotics. Thus, it is very important to prevent and eradicate biofilm on biliary catheters.

We evaluated the biofilm formation of cholangitis pathogenic bacteria on a catheter (Escherichia coli (va005491) isolated from a wound swab of a patient with chronic cholecystitis, and Salmonella enterica subsp. enterica serovar Derby (or Salmonella Derby) (bk 027538)) providing evidence that the treatment-either with locally administered photoresponsive ciprofloxacin derivate or ciprofloxacin showed a significant reduction of biofilm formation. We also evaluated the biofilm formation by bile duct microbiomes of antibiotic treatment for survival with cLSM (confocal Laser Scanning Microscopy), live/dead staining, and with computer image analyses (BiofilmAnalyzer). The antibiotic was also effective biofilms based on bile duct microbiomes, providing a variety of bacteria species and structures within biofilms mirroring more the natural communities on the catheter.

We also evaluated the effect of the photoresponsive antibiotic and its split products on eucaryotic liver cells and could exclude toxic effects .

The bactericidal properties of photoresponsive ciprofloxacin on bilioenteric catheters suggest a potential local prevention measure. The advantage is that the antimicrobial treatment remains without an overall undirected and potentially harmful effect, as observed in systemic antibiotic treatment. The contribution of photoresponsive ciprofloxacin to the cytotoxicity was low. Our work presents proof that photoresponsive antibiotics can prevent biofilm formation in the bilioenteric catheter. This might be feasible in medical routine and can eliminate biofilms from bile duct microbiomes.