As the medical community continues to battle against complex bacterial infections, a revolutionary approach has emerged from a collaborative effort by researchers at the Friedrich-Schiller-University in Jena, Germany. Published in the International Journal of Antimicrobial Agents, a new study has shed light on the efficacy of a photoactivatable form of the antibiotic ciprofloxacin, used in conjunction with bile acids, to target resistant biofilms in biliary diseases.

Biofilms, the protective layers formed by bacteria that adhere to surfaces, have been a significant hurdle in the treatment of infections related to bile duct catheters. These biofilms can lead to severe infections such as cholangitis, which are challenging to treat due to their resistance to traditional antibiotics. This innovative study explores the potential of using light-activated drugs in combination with naturally occurring bile acids to overcome this resistance.

The researchers, led by the interdisciplinary team of Eberhardt Nino, Santamarina Belen Gonzalez, and others, have focused their efforts on understanding the elusive bile duct microbiome, typically sterile in a healthy biliary system. However, in individuals with hepatobiliary diseases, biofilms can form on biliary drainage catheters, leading to a previously difficult-to-analyze bile microbiome.

The study utilized human-derived pathogenic bacterial isolates such as Salmonella enterica and Escherichia coli, as well as microbiomes extracted from catheter-derived bile ducts. By employing crystal violet staining, confocal laser scanning microscopy, and biofilm image analysis, the team quantified the impact of bile acids and the photoactivatable antibiotic on biofilm biomass and bacterial survival.

The results were highly promising: the photo-activated ciprofloxacin showed significant efficacy in preventing biofilm formation and reducing bacterial viability, all the while sparing eukaryotic cells from damage. Furthermore, combining antibiotics with bile acids like ursodesoxycholic acid (UDCA) only mildly impacted the biomass of biofilms but notably reduced the survival rate of bacteria within the biofilms.

This combinatorial treatment offers a two-pronged attack on biliary infections. While the antibiotics work to disrupt bacterial growth, bile acids seem to enhance their killing effect. Such an approach harnesses the endocrine and paracrine functions of bile acids beyond their conventional roles in the digestive system.

This study’s publication is not just a spotlight on a promising new treatment avenue but also provides a platform for further research and clinical application for challenging biliary infections. The research team, which boasts a strong background in organic chemistry, photonics, and microbial ecology, underscored the importance of interdisciplinary cooperation to innovate in the field of antimicrobial therapy.

The groundbreaking findings, as chronicled in the study DOI: 10.1016/j.ijantimicag.2024.107086, suggest that leveraging the power of light-activated therapeutics in unison with the body’s natural compounds might be the key to addressing what was once considered an impervious problem. The researchers also assured the scientific community that no conflicts of interest were involved in their investigation, ensuring the study’s integrity.

1. Eberhardt, N., et al. (2024). The effects of photoactivated ciprofloxacin and bile acids on biofilms on bile duct catheters. International Journal of Antimicrobial Agents, 107086. doi:10.1016/j.ijantimicag.2024.107086.

2. Hall-Stoodley, L., Costerton, J. W., & Stoodley, P. (2004). Bacterial biofilms: from the natural environment to infectious diseases. Nature Reviews Microbiology, 2(2), 95-108.

3. Høiby, N., et al. (2010). The clinical impact of bacterial biofilms. International Journal of Oral Science, 2(2), 55-65.

4. Lewis, K. (2001). Riddle of biofilm resistance. Antimicrobial Agents and Chemotherapy, 45(4), 999-1007.

5. Stroes-Gascoyne, S., & Schippers, A. (2011). Microbial communities in bentonite and their impact on the performance of bentonite in a repository for spent nuclear fuel. Applied Clay Science, 52(1-2), 85-91.


1. Photoactivated antibiotics
2. Bile duct biofilm infections
3. Ciprofloxacin biofilm treatment
4. Biliary catheter bacterial resistance
5. Ursodesoxycholic acid antimicrobial

With continued research and perhaps future clinical trials, this novel method holds promise for a significant leap in the treatment of biliary tract infections, posing a beacon of hope for patients suffering from these stubborn and life-threatening conditions.