title: Decontamination Efficacy of Ultraviolet Radiation against Biofilms of Common Nosocomial Bacteria.
abstract: BACKGROUND
  Ultraviolet radiation (UV) is commonly used to destroy microorganisms in the health-care environment. However, the efficacy of UV radiation against bacteria growing within biofilms has never been studied.
  
  
  OBJECTIVE
  To measure the sterilization effectiveness of UV radiation against common healthcare associated pathogens growing within biofilms.
  
  
  METHODS
  Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), Streptococcus epidermidis, Escherichia coli, ESBL-producing E. coli, Pseudomonas aeruginosa and Acinetobacter baumannii were cultivated in the Calgary Biofilm Device. Their biofilms were placed 50 cm from the UV lamp within the Biosafety Cabinet. Viability test, crystal violet assay and a scanning electron microscope were used to evaluate the germicidal efficacy.
  
  
  RESULTS
  Within 5 minutes, UV radiation could kill S. aureus, MRSA, S. epidermidis, A. baumannii and ESBL-producing E. coli completely while it required 20 minutes and 30 minutes respectively to kill E. coli and P. aeruginosa. However, the amounts of biomass and the ultrastructure between UV-exposed biofilms and controls were not significantly different.
  
  
  CONCLUSIONS
  UV radiation is effective in inactivating nosocomial pathogens grown within biofilms, but not removing biofilms and EPS. The biofilm of P. aeruginosa was the most durable.
authors.forename: Pholawat
authors.initials: P
authors.lastname: Tingpej
authors.forename: Rattana
authors.initials: R
authors.lastname: Tiengtip
authors.forename: Sumalee
authors.initials: S
authors.lastname: Kondo
mesh_terms: D001419:Bacteria / Q000302:isolation & purification / Q000528:radiation effects*; D018441:Biofilms / Q000528:radiation effects*; D003428:Cross Infection / Q000382:microbiology; D003666:Decontamination / Q000379:methods*; D006801:Humans; D014466:Ultraviolet Rays