title: Additive Effect of MCP in Combination with Cefotaxime Against Staphylococcus aureus.
abstract: BACKGROUND
  Pectin is a heterogeneous polysaccharide present in plants and citrus fruits. It exhibits different beneficial biological activities. Conflicting reports exist about the antimicrobial effect of pectin and its derivatives.
  
  
  OBJECTIVE
  In this study, we investigate the antimicrobial effect of Modified Citrus Pectin (MCP) against Staphylococcus aureus, a pathogen showing increasing rates of antimicrobial resistance worldwide.
  
  
  METHODS
  Forty-three clinical isolates of S. aureus were obtained from a hospital in North Lebanon. Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs) were determined using MCP after determining its optimum pH activity. The combination between MCP and cefotaxime was then investigated for S. aureus isolates using the checkerboard technique.
  
  
  CONCLUSIONS
  The optimum pH for the activity of MCP was 6.0. MIC and MBC values against S. aureus ranged between 0.39-50 µg/µl and 3.13-50 µg/µl, respectively. These values are promising for using MCP in the inhibition of some S. aureus isolates at relatively low concentrations. Combination experiments showed an additive effect in most S. aureus strains between MCP and cefotaxime, and a synergistic effect in two strains. These preliminary findings open the way for further investigation into the therapeutic potential of MCP in the treatment of S. aureus infections.
  
  
  CONCLUSIONS
  MCP demonstrates in vitro antimicrobial activity alone and in combination with cefotaxime against S. aureus.
authors.affiliation: Faculty of Medicine, University of Balamand, El-Koura. Lebanon.
authors.forename: Elias
authors.initials: E
authors.lastname: Dahdouh
authors.affiliation: Department of Biology, University of Balamand, Al-Koura. Lebanon.
authors.forename: Salah
authors.initials: S
authors.lastname: El-Khatib
authors.affiliation: Department of Biology, American University of Beirut, Beirut. Lebanon.
authors.forename: Elias
authors.initials: E
authors.lastname: Baydoun
authors.affiliation: Department of Biology, University of Balamand, P.O. Box: 100 Tripoli. Lebanon.
authors.forename: Roula M
authors.initials: RM
authors.lastname: Abdel-Massih
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002439:Cefotaxime / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004357:Drug Synergism; D006863:Hydrogen-Ion Concentration; D010368:Pectins / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; C586814:citrus pectin; D010368:Pectins; D002439:Cefotaxime
keywords: Antibiotic resistance; MRSA; Staphylococcus aureus; checkerboard; combination therapy; modified citrus pectin