Editor: Robert Burne
The synergistic activity of triclosan and ciprofloxacin on biofilms of Salmonella Typhimurium
Article first published online: 23 SEP 2009
© 2009 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Microbiology Letters
Volume 301, Issue 1, pages 69–76, December 2009
How to Cite
Tabak, M., Scher, K., Chikindas, M. L. and Yaron, S. (2009), The synergistic activity of triclosan and ciprofloxacin on biofilms of Salmonella Typhimurium. FEMS Microbiology Letters, 301: 69–76. doi: 10.1111/j.1574-6968.2009.01804.x
- Issue published online: 2 NOV 2009
- Article first published online: 23 SEP 2009
- Received 15 April 2009; accepted 8 September 2009.Final version published online 16 October 2009.
- antibiotic resistance
Triclosan is a biocide whose wide use has raised a debate about the potential benefits vs. hazards of the incorporation of antimicrobials in consumer products. The purpose of the present study was to determine whether exposure of biofilms of Salmonella enterica serovar Typhimurium to triclosan influences the tolerance of the bacteria towards antibiotics such as ciprofloxacin and vice versa. A synergistic antibiofilm activity was observed when the biofilms were treated with triclosan before or together with ciprofloxacin, and an additive activity was observed with planktonic cells. For example 500 μg mL−1 triclosan and 500 μg mL−1 ciprofloxacin reduced the number of viable cells in the biofilm by 1.6 and 0.5 log, respectively. However, the sequential treatment of 500 μg mL−1 triclosan followed by ciprofloxacin resulted in 4.8 log reduction. Combination indexes (CI) for biofilms treated with triclosan followed by ciprofloxacin were 0.7, 0.32 and 0.25 for reduction of 90%, 99% and 99.9%, respectively, indicating a synergism. For planktonic cells, CIs were 1±0.1, indicating an additive effect. Therefore, it was suggested that triclosan weakens the ability of biofilm-associated cells to survive exposure to ciprofloxacin in the biofilm, probably by improving the permeability or the activity of ciprofloxacin.