title: Subinhibitory concentration of ciprofloxacin targets quorum sensing system of Pseudomonas aeruginosa causing inhibition of biofilm formation & reduction of virulence.
abstract: OBJECTIVE
  Biofilms formed by pseudomonas aeruginosa lead to persistent infections. Use of antibiotics for the treatment of biofilm induced infection poses a threat towards development of resistance. Therefore, the research is directed towards exploring the property of antibiotics which may alter the virulence of an organism besides altering its growth. The aim of this study was to evaluate the role of subinhibitory concentration of ciprofloxacin (CIP) in inhibiting biofilm formation and virulence of P. aeruginosa.
  
  
  METHODS
  Antibiofilm potential of subinhibitory concentration of CIP was evaluated in terms of log reduction, biofilm forming capacity and coverslip assay. P. aeruginosa isolates (grown in the presence and absence of sub-MIC of CIP) were also evaluated for inhibition in motility, virulence factor production and quorum sensing (QS) signal production.
  
  
  RESULTS
  Sub-minimum inhibitory concentration (sub-MIC) of CIP significantly reduced the motility of P. aeruginosa stand and strain and clinical isolates and affected biofilm forming capacity. Production of protease, elastase, siderophore, alginate, and rhamnolipid was also significantly reduced by CIP.
  
  
  CONCLUSIONS
  Reduction in virulence factors and biofilm formation was due to inhibition of QS mechanism which was indicated by reduced production of QS signal molecules by P. aeruginosa in presence of subinhibitory concentration of CIP.
authors.affiliation: Department of Microbiology, Panjab University, Chandigarh, India.
authors.forename: Parul
authors.initials: P
authors.lastname: Gupta
authors.affiliation: Department of Microbiology, Panjab University, Chandigarh, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Chhibber
authors.affiliation: Department of Microbiology, Panjab University, Chandigarh, India.
authors.forename: Kusum
authors.initials: K
authors.lastname: Harjai
mesh_terms: D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002939:Ciprofloxacin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000472:pathogenicity; D053038:Quorum Sensing / Q000187:drug effects* / Q000235:genetics; D014774:Virulence / Q000187:drug effects
chemical_list: D002939:Ciprofloxacin