Abstract: Polichloride vinyl (PCV) is a widely used thermoplastic polymer, also in the
production of medical devices. In the present study we assess the infl uence of EDTA in
vitro on the biofi lm structure formed by Staphylococcus epidermidis isolates on PCV
biomaterials (Nelaton and Thorax catheters). The 6 strains of S. epidermidis were isolated
from nasopharynx of hospitalised patients. It was found that all isolates were able to form
the biofi lm on both PCV biomaterials, irrespective of adhesion properties (cell surface
properties, ability to slime production, minimal time needed for adhesion). The EDTA
showed bacteriostatic effect against planktonic cells of the isolates (MIC = 0.25–0.5
mmol/l; MBC = 10.0–>25.0 mmol/l; MBC/MIC = 20, 30, 40, >50). The adhesion process
and also formation of the biofi lm was inhibited by EDTA at concentrations 1.0–2.0
mmol/l (2–8 × MIC). The eradication of the mature biofi lm was achieved at 2.0–4.0
mmol/l EDTA (4–8 × MIC) for two strains, while for the other four isolates, concentration
of EDTA needed for eradication effect was >32 mmol/l (> 128 × MIC). Data obtained in
this paper suggest that EDTA may be regarded as a useful agent preventing formation of
the S. epidermidis biofi lm on PCV biomaterials.