title: Enterococcus--virulence and susceptibility to photodynamic therapy of clinical isolates from Lower Silesia, Poland.
abstract: BACKGROUND
  A collection of 400 enterococcal isolates from clinical samples of hospitalized patients were studied for their virulence traits according to the isolation site. Formation of biofilm and production of DNase, hemolysin, lipase, and gelatinase were characterized. Biofilms of selected strains were examined for their susceptibility to antimicrobial photodynamic therapy (aPDT).
  
  
  METHODS
  All strains were tested for biofilm production by microtiter method and the activity of hemolysin, gelatinase, lipase, and DNase by plate method with an adequate substrate. Photodynamic therapy with Photolon and red laser light was performed towards 48 h biofilms of eight representative strains. The viability of biofilms was tested by the BactLight assay and visualized under a fluorescent microscope.
  
  
  RESULTS
  Among the 400 isolates, 69.8% strains of Enterococcus faecalis, 30% of Enterococcus faecium, and 0.2% of Enterococcus casseliflavus were identified. In vitro, production of biofilm was found in 65.7% of enterococci. Biofilm-positive strains were isolated from urinary tract infections (81%), wound infections (71%), respiratory tract infections (62%), and gastrointestinal tract (47%) (colonization). Hemolysin activity was observed in 28.5%, gelatinase in 24.5%, lipase in 23%, and DNase in 3.5% of all, mostly biofilm-positive, isolates. Photodynamic therapy with Photolon efficiently reduced the enterococcal biofilms.
  
  
  CONCLUSIONS
  The study demonstrated the high prevalence of biofilm-producing clinical enterococci, their virulence potential being higher than for biofilm-negative strains, and the susceptibility to aPDT of mature biofilms produced by strains, regardless of their species and site of isolation.
authors.affiliation: Department of Microbiology, Wrocław Medical University , Wrocław , Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Dworniczek
authors.forename: Justyna
authors.initials: J
authors.lastname: Piwowarczyk
authors.forename: Alicja
authors.initials: A
authors.lastname: Seniuk
authors.forename: Grażyna
authors.initials: G
authors.lastname: Gościniak
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D018441:Biofilms; D016983:Enterococcus / Q000187:drug effects / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D016984:Enterococcus faecium / Q000187:drug effects / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D010641:Phenotype; D010778:Photochemotherapy; D011044:Poland / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors
keywords: Enterococcus; antimicrobial photodynamic therapy; biofilm