Effects of alcohols, povidone-iodine and hydrogen peroxide on biofilms of Staphylococcus epidermidis.
OBJECTIVE
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 10(3) 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.
Presterl
Elisabeth
E
Division of Infectious Diseases, Department of Medicine I, Medical University of Vienna, Vienna, Austria. elisabeth.presterl@meduniwien.ac.at
Suchomel
Miranda
M
Eder
Michaela
M
Reichmann
Sonja
S
Lassnigg
Andrea
A
Graninger
Wolfgang
W
Rotter
Manfred
M
D000433:1-Propanol / Q000494:pharmacology; D000438:Alcohols / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D016470:Bacteremia / Q000382:microbiology; D018441:Biofilms / Q000187:drug effects*; D002710:Chlorhexidine / Q000494:pharmacology; D004202:Disinfectants / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D011206:Povidone-Iodine / Q000494:pharmacology*; D016459:Prosthesis-Related Infections / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000187:drug effects* / Q000502:physiology*
D000438:Alcohols; D000891:Anti-Infective Agents, Local; D004202:Disinfectants; D000431:Ethanol; D011206:Povidone-Iodine; D000433:1-Propanol; D006861:Hydrogen Peroxide; D002710:Chlorhexidine