title: Anti-Pseudomonas aeruginosa activity of 1,10-phenanthroline-based drugs against both planktonic- and biofilm-growing cells.
abstract: OBJECTIVE
  The beneficial antimicrobial properties of 1,10-phenanthroline (phen)-based drugs, together with the imperative need to develop new chemotherapeutic options for prevention/treatment of infections caused by MDR Gram-negative bacteria, led us to evaluate the effects of phen, 1,10-phenanthroline-5,6-dione (phendione), [Ag(phendione)2]ClO4 and [Cu(phendione)3](ClO4)2·4H2O on planktonic- and biofilm-growing Pseudomonas aeruginosa.
  
  
  METHODS
  Thirty-two non-duplicated Brazilian clinical isolates of P. aeruginosa with distinct genetic backgrounds were used in all experiments. The effect of test compounds on planktonic bacterial proliferation was determined as recommended by CLSI protocol. The effect on biofilm formation was evaluated by crystal violet incorporation (biomass determination) and XTT (viability assay). Mature biofilm disorganization was evidenced by staining with crystal violet.
  
  
  RESULTS
  Phen-based compounds presented anti-P. aeruginosa activity, but with different potencies concerning the geometric mean MIC: [Cu(phendione)3](2+) (7.76 μM) > [Ag(phendione)2](+) (14.05 μM) > phendione (31.15 μM) > phen (579.28 μM). MICs of each compound were similar irrespective of whether the P. aeruginosa isolates were susceptible or resistant to classical antimicrobials (ceftazidime, meropenem and imipenem). The pretreatment of bacteria with phen, phendione and phendione's metal derivatives at 0.5 × MIC value inhibited biofilm formation, particularly the use of [Cu(phendione)3](2+) and [Ag(phendione)2](+), which significantly reduced both biomass (48% and 44%, respectively) and viability (78% and 77%, respectively). The compounds studied also disrupted mature biofilm in a dose-dependent manner, especially [Ag(phendione)2](+) and [Cu(phendione)3](2+) (IC50, 9.39 and 10.16 μM, respectively).
  
  
  CONCLUSIONS
  Coordination of phendione to Ag(+) and Cu(2+) represents a new promising group of anti-infective agents, which revealed a potent anti-P. aeruginosa action against both planktonic- and biofilm-growing cells.
authors.affiliation: General Microbiology Department, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil The Inorganic Pharmaceutical and Biomimetic Research Centre, Focas Research Institute, Dublin Institute of Technology, Dublin, Ireland.
authors.forename: Livia
authors.initials: L
authors.lastname: Viganor
authors.affiliation: General Microbiology Department, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil Biochemistry Post-Graduation Programme, Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Anna Clara M
authors.initials: AC
authors.lastname: Galdino
authors.affiliation: Pathology Department and Infection Diseases Post-Graduation Programme, Federal University of Espírito Santo, Espírito Santo, Brazil.
authors.forename: Ana Paula F
authors.initials: AP
authors.lastname: Nunes
authors.affiliation: Medical Microbiology Department, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Kátia R N
authors.initials: KR
authors.lastname: Santos
authors.affiliation: General Microbiology Department, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Marta H
authors.initials: MH
authors.lastname: Branquinha
authors.affiliation: The Inorganic Pharmaceutical and Biomimetic Research Centre, Focas Research Institute, Dublin Institute of Technology, Dublin, Ireland.
authors.forename: Michael
authors.initials: M
authors.lastname: Devereux
authors.affiliation: School of Chemical Sciences and the National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
authors.forename: Andrew
authors.initials: A
authors.lastname: Kellett
authors.affiliation: Chemistry Department, Maynooth University, National University of Ireland, Maynooth, Ireland.
authors.forename: Malachy
authors.initials: M
authors.lastname: McCann
authors.affiliation: General Microbiology Department, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil The Inorganic Pharmaceutical and Biomimetic Research Centre, Focas Research Institute, Dublin Institute of Technology, Dublin, Ireland andre@micro.ufrj.br.
authors.forename: André L S
authors.initials: AL
authors.lastname: Santos
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D001938:Brazil; D003300:Copper / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D010618:Phenanthrolines / Q000494:pharmacology*; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D012834:Silver / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D010618:Phenanthrolines; D012834:Silver; D003300:Copper; C025205:1,10-phenanthroline