title: [Phenotypic evaluation of hydrophobicity and the ability to produce biofilm in coagulase-negative staphylococci isolated from infected very-low-birthweight newborns].
abstract: BACKGROUND
  Coagulase-negative staphylococci (CNS), particularly Staphylococcus epidermidis and Staphylococcus haemolyticus, are the leading cause of infection among infants with very low birth weight (<1500 g). The most important virulence factor of these pathogens is their ability to form biofilm. The aim of this study was to evaluate the surface properties, the ability to produce slime and biofilm formation of S. epidermidis and S. haemolyticus strains isolated from infections in very low birth weight neonates.
  
  
  METHODS
  Isolates ofS. epidermidis (n=60) and S. haemolyticus (n=38) were obtained from neonates, hospitalized in two neonatal intensive care units in Poland. Cell surface hydrophobicity was determined by autoagglutination test (AA) in 0.9% NaCl and salt aggregation test (SAT) in ammonium sulphate solution. In order to determine the ability to produce slime, Christiensen's tube test with safranin staining and Congo Red Agar (CRA) test were carried out. The quantitative assessment of biofilm production was determined by crystal violet (CV) assay.
  
  
  RESULTS
  Based on the AA test, it was demonstrated that almost all S. epidermidis and S. haemolyticus isolates showed no agglutination in sodium chloride saline. The SAT test indicated that the greatest number ofS. epidermidis isolates aggregated in concentration of 2 M, whereas, for S. haemolyticus, it was 0.5 M. In the Christiensen's method, the largest amount of the S. epidermidis isolates produced a small amount of slime (40%), whereas 68% of the S. haemolyticus isolates produced a large amount of slime. In CRA test, in both species, the most common result was the bacterial culture colour being almost black, which corresponds to low production of biofilm. Quantitative assessment of biofilm production in CV assay revealed that while 97% of the S. heamolyticus isolates produced high levels of biofilm, similar results were observed in only 43% of the S. epidermidis isolates.
  
  
  CONCLUSIONS
  Based on the results obtained by phenotypic methods, it was demonstrated that the S. haemolyticus isolates showed a statistically significant stronger ability to produce mucus and form biofilm than the isolates ofS. epidermidis.
authors.affiliation: Zaklad Bakteriologii, Ekologii Drobnoustrojów i Parazytologii, Katedry Mikrobiologii Uniwersytet Jagiellofiski Collegium Medicum.
authors.forename: Monika
authors.initials: M
authors.lastname: Grzebyk
authors.affiliation: Zaklad Bakteriologii, Ekologii Drobnoustrojów i Parazytologii, Katedry Mikrobiologii Uniwersytet Jagiellofiski Collegium Medicum.
authors.forename: Wloch Monika
authors.initials: WM
authors.lastname: Brzychczy-
authors.affiliation: Zaklad Bakteriologii, Ekologii Drobnoustrojów i Parazytologii, Katedry Mikrobiologii Uniwersytet Jagiellofiski Collegium Medicum.
authors.forename: Anna
authors.initials: A
authors.lastname: Piotrowska
authors.affiliation: Zaklad Mikologii, Katedra Mikrobiologii Uniwersytet Jagielloński Collegium Medicum,
authors.forename: Pawel
authors.initials: P
authors.lastname: Krzyściak
authors.affiliation: Zaklad Bakteriologii, Ekologii Drobnoustrojów i Parazytologii, Katedry Mikrobiologii Uniwersytet Jagiellofiski Collegium Medicum.
authors.forename: Piotr B
authors.initials: PB
authors.lastname: Heczko
authors.affiliation: Zaklad Epidemiologii Zakazeń, Katedra Mikrobiologii Uniwersytet Jagielloński Collegium Medicum.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Bulanda
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D003030:Coagulase / Q000378:metabolism*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000382:microbiology*; D019102:Infant, Very Low Birth Weight; D007363:Intensive Care Units, Neonatal; D013203:Staphylococcal Infections / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000378:metabolism* / Q000472:pathogenicity; D041162:Staphylococcus haemolyticus / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence
chemical_list: D003030:Coagulase