JAC Advance Access published online on June 22, 2007
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkm221
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Effects of alcohols, povidone-iodine and hydrogen peroxide on biofilms of Staphylococcus epidermidis
1 Division of Infectious Diseases, Department of Medicine I, Medical University of Vienna, Vienna, Austria 2 Department of Medical Microbiology, Institute of Hygiene, Medical University of Vienna, Vienna, Austria 3 Department of Biomaterials, Max-Planck-Institute of Colloids and Interfaces, Medical University of Vienna, Potsdam, Germany 4 Division of Cardiothoracic Anaesthesia, Department of Anaesthesia and General Intensive Care Medicine, Medical University of Vienna, Vienna, Austria
Received 19 December 2006; returned 27 January 2007; revised 15 May 2007; accepted 25 May 2007
* Corresponding author. Tel: +43-1-40400-5161; Fax: +43-1-40400-5162; E-mail: elisabeth.presterl{at}meduniwien.ac.at
Objectives: To test the effects of several biocides [N-propanol, a commercially available propanol/ethanol/chlorhexidine mixture, polyvinylpyrolidone (povidone-iodine) and hydrogen peroxide] on established biofilms of Staphylococcus epidermidis isolated from patients with cardiac implant infections and catheter-related bacteraemia.
Methods: Biofilms were grown in microtitre plates for 24 h, dyed and stained with Crystal Violet. The mean optical density (OD) and the OD ratio (ODr = OD of the treated biofilm/OD of the untreated biofilm) were used for quantification. Biofilms were incubated with 60% (v/v) N-propanol, the mixture of propanol/ethanol/chlorhexidine, hydrogen peroxide at three concentrations (0.5%, 3% and 5%, v/v) and povidone-iodine for 1, 5, 15, 30 and 60 min. Unstained biofilms were sonicated and plated on Columbia agar for time–kill curves. S. epidermidis skin isolates from healthy volunteers were used as controls.
Results: Biofilm ODs of the clinical S. epidermidis isolates and the isolates from the healthy volunteers were significantly different (1.17 ± 0.512 versus 0.559 ± 0.095, respectively; mean ± SD) (P < 0.01). No viable S. epidermidis was detected in biofilms treated with the alcohols, N-propanol or the propanol/ethanol/chlorhexidine mixture. Incubation with povidone-iodine and hydrogen peroxide 3% and 5% led to a log reduction of the viable cells of >5 after incubation for 5 min, however, up to 103 viable cells were detected in four isolates after 30 min of incubation with povidone-iodine.
Conclusions: S. epidermidis obtained from infected implants forms thicker biofilms than that of healthy volunteers. Hydrogen peroxide, at a concentration of 3% and 5%, and alcohols rapidly eradicate S. epidermidis biofilms, whereas povidone-iodine is less effective.
Key Words: S. epidermidis , biocides , staphylococci