title: Eradication of Pseudomonas aeruginosa Biofilms Using the Combination of n-butanolic Cyclamen coum Extract and Ciprofloxacin.
abstract: BACKGROUND
  Biofilm formation is a major pathogenic factor in different bacteria such as Pseudomonas aeruginosa. A number of studies have reported that bacterial biofilms show different levels of antibiotic resistance. In order to re-sensitize the bacterial biofilms to antibiotics, biofilms should be dispersed.
  
  
  OBJECTIVE
  In this study, the effect of n-butanolic Cyclamen coum extract in combination with ciprofloxacin was examined on one, three and five day old P. aeruginosa biofilms. The synergistic effect of n-butanolic C. coum extract and ciprofloxacin towards dispersing pre-established P. aeruginosa biofilms was also studied.
  
  
  METHODS
  The ability of biofilm formation by six different P. aeruginosa strains was confirmed by microtiter plate method and PCR assay for the cupA gene. The extraction of C. coum tubers was achieved by fractionation method using different solvents. The minimum inhibitory concentration (MIC) of n-butanolic C. coum extract and ciprofloxacin against planktonic cells was evaluated using agar well diffusion and microdilution methods. The microdilution chequerboard method was used to determine the fractional biofilm eradication concentration index (FBCI), when the combination of n-butanolic C. coum extract and ciprofloxacin were used against P. aeruginosa biofilms.
  
  
  RESULTS
  The ability of biofilm formation by P. aeruginosa strains was quantitatively confirmed. The PCR method confirmed the existence of cup A gene (172 bp) in all studied strains. Saponin content of the n-butanolic C. coum extract was 156 µg/mL. The extract revealed antibacterial activity against planktonic cells of P. aeruginosa strains. The results showed that one and three day old biofilms are affected by either ciprofloxacin or n-butanolic C. coum extract. However, n-butanolic C. coum extract in combination with ciprofloxacin was significantly more effective against P. aeruginosa biofilms.
  
  
  CONCLUSIONS
  Using n-butanolic C. coum extract in combination with ciprofloxacin offers a novel strategy to control biofilm-based infections caused by P. aeruginosa.
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, IR Iran.
authors.forename: Morvarid
authors.initials: M
authors.lastname: Shafiei
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, IR Iran.
authors.forename: Ahya
authors.initials: A
authors.lastname: Abdi Ali
authors.affiliation: Department of Bacteriology, Pasteur Institute of Iran, Tehran, IR Iran.
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Shahcheraghi
authors.affiliation: Department of Biology, Faculty of Science, Alzahra University, Tehran, IR Iran.
authors.forename: Azra
authors.initials: A
authors.lastname: Saboora
authors.affiliation: Department of Molecular Genetics, National Institute of Genetic Engineering and Biotechnology, Tehran, IR Iran.
authors.forename: Kambiz
authors.initials: K
authors.lastname: Akbari Noghabi
keywords: Biofilm; Cyclamen coum; Pseudomonas aeruginosa