title: Photodynamic antibacterial enhanced effect of methylene blue-gold nanoparticles conjugate on Staphylococcal aureus isolated from impetigo lesions in vitro study.
abstract: BACKGROUND
  Staphylococcal aureus is the most common organism which has been encountered in impetigo infection. Gold nanoparticles can be used as a tool to deliver antimicrobials or to enhance photodynamic destruction of bacteria.
  
  
  OBJECTIVE
  To evaluate the photodynamic effect of methylene blue gold nanoparticles (MB-gold nanoparticles conjugate) on S. aureus which were isolated from impetigo lesions.
  
  
  METHODS
  Twenty children were diagnosed clinically as impetigo, and aged from 3 to 5 years of both sexes were recruited in the study. Two bacteriological samples were collected from each patient, identified and cultured. Samples of S. aureus of a concentration of 10(-1)ml were divided into four groups. S. aureus was treated by MB-gold nanoparticles conjugate, gold nanoparticles, MB, and the fourth group served as a control group. Diode laser (660 nm) was used for photoactivation. The bacterial growth inhibition was determined by two methods: the percentage of reduction of viable bacteria count and the optical density (O.D) of bacterial growth.
  
  
  RESULTS
  The highest significant inhibitory effect on S. aureus was obtained with MB-gold nanoparticles conjugate when irradiated by diode laser 660 nm (P < 0.0001). The percentage of viable bacteria was 3%. The photoactivated gold nanoparticles showed a significant inhibitory effect on bacterial growth (P < 0.05). A non-significant inhibitory effect was elicited in other groups.
  
  
  CONCLUSIONS
  The photoactivated MB-gold nanoparticles conjugate showed the maximum inhibitory effect on S. aureus activity. The gold nanoparticles proved efficacy as a drug delivery system. It enhanced the photodynamic antibacterial effect of methylene blue.
authors.affiliation: Dermatology Unit, Medical Laser Department, National Institute of Laser Enhanced Sciences Cairo University, Egypt. Electronic address: dr.abeertawfik@gmail.com.
authors.forename: Abeer Attia
authors.initials: AA
authors.lastname: Tawfik
authors.affiliation: Pediatrics Unit, Medical Laser Department, National Institute of Laser Enhanced Sciences Cairo University, Egypt.
authors.forename: Jehan
authors.initials: J
authors.lastname: Alsharnoubi
authors.affiliation: Biology Unit, Medical Laser Department, National Institute of Laser Enhanced Sciences Cairo University, Egypt.
authors.forename: Mona
authors.initials: M
authors.lastname: Morsy
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001431:Bacteriological Techniques; D002675:Child, Preschool; D004337:Drug Carriers; D005260:Female; D006046:Gold / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007169:Impetigo / Q000188:drug therapy / Q000382:microbiology; D054023:Lasers, Semiconductor; D008297:Male; D053768:Metal Nanoparticles; D008751:Methylene Blue / Q000008:administration & dosage / Q000494:pharmacology*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D004337:Drug Carriers; D017319:Photosensitizing Agents; D006046:Gold; D008751:Methylene Blue
keywords: Diode laser; Gold nanoparticles; Methylene blue