title: Antibacterial activity of extracellular compounds produced by a Pseudomonas strain against methicillin-resistant Staphylococcus aureus (MRSA) strains.
abstract: BACKGROUND
  The emergence of multidrug-resistant bacteria is a world health problem. Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA) strains, is one of the most important human pathogens associated with hospital and community-acquired infections. The aim of this work was to evaluate the antibacterial activity of a Pseudomonas aeruginosa-derived compound against MRSA strains.
  
  
  METHODS
  Thirty clinical MRSA strains were isolated, and three standard MRSA strains were evaluated. The extracellular compounds were purified by vacuum liquid chromatography. Evaluation of antibacterial activity was performed by agar diffusion technique, determination of the minimal inhibitory concentration, curve of growth and viability and scanning electron microscopy. Interaction of an extracellular compound with silver nanoparticle was studied to evaluate antibacterial effect.
  
  
  RESULTS
  The F3 (ethyl acetate) and F3d (dichloromethane- ethyl acetate) fractions demonstrated antibacterial activity against the MRSA strains. Phenazine-1-carboxamide was identified and purified from the F3d fraction and demonstrated slight antibacterial activity against MRSA, and synergic effect when combined with silver nanoparticles produced by Fusarium oxysporum. Organohalogen compound was purified from this fraction showing high antibacterial effect. Using scanning electron microscopy, we show that the F3d fraction caused morphological changes to the cell wall of the MRSA strains.
  
  
  CONCLUSIONS
  These results suggest that P. aeruginosa-produced compounds such as phenazines have inhibitory effects against MRSA and may be a good alternative treatment to control infections caused by MRSA.
authors.affiliation: Department of Microbiology, Biology Sciences Center, University of Londrina State, Londrina, PR CP 86005-990, Brazil.
authors.forename: Viviane F
authors.initials: VF
authors.lastname: Cardozo
authors.forename: Admilton G
authors.initials: AG
authors.lastname: Oliveira
authors.forename: Erick K
authors.initials: EK
authors.lastname: Nishio
authors.forename: Marcia R E
authors.initials: MR
authors.lastname: Perugini
authors.forename: Célia G T J
authors.initials: CG
authors.lastname: Andrade
authors.forename: Wanderley D
authors.initials: WD
authors.lastname: Silveira
authors.forename: Nelson
authors.initials: N
authors.lastname: Durán
authors.forename: Galdino
authors.initials: G
authors.lastname: Andrade
authors.forename: Renata K T
authors.initials: RK
authors.lastname: Kobayashi
authors.forename: Gerson
authors.initials: G
authors.lastname: Nakazato
mesh_terms: D000085:Acetates / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D002473:Cell Wall / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D004357:Drug Synergism; D005670:Fusarium / Q000737:chemistry; D006219:Halogens / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D053768:Metal Nanoparticles / Q000737:chemistry; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D008752:Methylene Chloride / Q000737:chemistry; D050296:Microbial Viability; D010619:Phenazines / Q000737:chemistry / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D012834:Silver / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000085:Acetates; D000900:Anti-Bacterial Agents; D006219:Halogens; D010619:Phenazines; C420923:phenazine-1-carboxamide; D012834:Silver; D008752:Methylene Chloride; C007650:ethyl acetate