title: Eugenol: a phyto-compound effective against methicillin-resistant and methicillin-sensitive Staphylococcus aureus clinical strain biofilms.
abstract: BACKGROUND
  Inhibition and eradication of Staphylococcus aureus biofilms with conventional antibiotic is difficult, and the treatment is further complicated by the rise of antibiotic resistance among staphylococci. Consequently, there is a need for novel antimicrobials that can treat biofilm-related infections and decrease antibiotics burden. Natural compounds such as eugenol with anti-microbial properties are attractive agents that could reduce the use of conventional antibiotics. In this study we evaluated the effect of eugenol on MRSA and MSSA biofilms in vitro and bacterial colonization in vivo.
  
  
  RESULTS
  Effect of eugenol on in vitro biofilm and in vivo colonization were studied using microtiter plate assay and otitis media-rat model respectively. The architecture of in vitro biofilms and in vivo colonization of bacteria was viewed with SEM. Real-time RT-PCR was used to study gene expression. Check board method was used to study the synergistic effects of eugenol and carvacrol on established biofilms. Eugenol significantly inhibited biofilms growth of MRSA and MSSA in vitro in a concentration-dependent manner. Eugenol at MIC or 2×MIC effectively eradicated the pre-established biofilms of MRSA and MSSA clinical strains. In vivo, sub-MIC of eugenol significantly decreased 88% S. aureus colonization in rat middle ear. Eugenol was observed to damage the cell-membrane and cause a leakage of the cell contents. At sub-inhibitory concentration, it decreases the expression of biofilm-and enterotoxin-related genes. Eugenol showed a synergistic effect with carvacrol on the eradication of pre-established biofilms.
  This study demonstrated that eugenol exhibits notable activity against MRSA and MSSA clinical strains biofilms. Eugenol inhibited biofilm formation, disrupted the cell-to-cell connections, detached the existing biofilms, and killed the bacteria in biofilms of both MRSA and MSSA with equal effectiveness. Therefore, eugenol may be used to control or eradicate S. aureus biofilm-related infections.
authors.affiliation: Institute for Medical Device Clinical Trials, Korea University College of Medicine, Seoul, South Korea; Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Mukesh Kumar
authors.initials: MK
authors.lastname: Yadav
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Sung-Won
authors.initials: SW
authors.lastname: Chae
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Gi Jung
authors.initials: GJ
authors.lastname: Im
authors.affiliation: Laboratory of Medicine, Dongguk University Ilsan Hospital, Goyang, Gyeonggi, South Korea.
authors.forename: Jae-Woo
authors.initials: JW
authors.lastname: Chung
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Jae-Jun
authors.initials: JJ
authors.lastname: Song
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D000081007:Cymenes; D004357:Drug Synergism; D005054:Eugenol / Q000494:pharmacology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics; D039821:Monoterpenes / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000081007:Cymenes; D039821:Monoterpenes; D005054:Eugenol; C073316:carvacrol