The synergistic activity of triclosan and ciprofloxacin on biofilms of Salmonella Typhimurium.
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 microg mL(-1) triclosan and 500 microg 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 microg 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.
Technion-Israel Institute of Technology, Faculty of Biotechnology and Food Engineering, Haifa, Israel.
Mina
M
Tabak
Keren
K
Scher
Michael L
ML
Chikindas
Sima
S
Yaron
D000890:Anti-Infective Agents / Q000008:administration & dosage*; D018441:Biofilms / Q000187:drug effects*; D002939:Ciprofloxacin / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D008826:Microbial Sensitivity Tests; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000502:physiology; D014260:Triclosan / Q000008:administration & dosage*
D000890:Anti-Infective Agents; D014260:Triclosan; D002939:Ciprofloxacin