Cerium, chitosan and hamamelitannin as novel biofilm inhibitors?
OBJECTIVE
The colonization of indwelling medical devices and subsequent biofilm formation represents a global challenge since it promotes the persistence of infection and contributes to antimicrobial resistance. The aim of this study was to determine the antimicrobial activity of cerium, chitosan and hamamelitannin against usual microbial colonizers and to assess their efficacy regarding biofilm formation on polyurethane (PUR)-like catheters.


METHODS
The antimicrobial and anti-biofilm effect of cerium nitrate, low molecular weight chitosan (LMWC) and hamamelitannin was tested against Staphylococcus epidermidis, Staphylococcus aureus, Acinetobacter baumannii and Candida albicans strains. Biofilm formation was assessed with PUR-like catheter segments and the metabolic activity was quantified by colorimetry with a tetrazolium reduction assay.


RESULTS
Cerium nitrate and LMWC inhibited the microbial growth of all microbial strains tested; hamamelitannin showed no inhibition. Regarding biofilm formation on PUR-like catheters, with subinhibitory concentrations: cerium nitrate significantly inhibited the metabolic activity of C. albicans; LMWC reduced the metabolic activity of S. epidermidis and C. albicans; and hamamelitannin decreased the metabolic activity of all tested bacteria, but not of yeasts.


CONCLUSIONS
The microbicidal activity of cerium nitrate and LMWC was clearly demonstrated in this study, as was their fungistatic effect at lower concentrations. Hamamelitannin significantly reduced biofilm metabolic activity of all tested bacteria. These microbial inhibitors may play a promising role regarding different biomedical applications.
Department of Microbiology, Faculty of Medicine, University of Porto, Porto, Portugal. lcobrado@med.up.pt
L
L
Cobrado
M M
MM
Azevedo
A
A
Silva-Dias
J Pedro
JP
Ramos
C
C
Pina-Vaz
A G
AG
Rodrigues
D000890:Anti-Infective Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002176:Candida albicans / Q000187:drug effects* / Q000254:growth & development; D057785:Catheters / Q000382:microbiology; D002563:Cerium / Q000494:pharmacology*; D048271:Chitosan / Q000494:pharmacology*; D003124:Colorimetry / Q000379:methods; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D006601:Hexoses / Q000494:pharmacology*; D006801:Humans; D011140:Polyurethanes; D013194:Staining and Labeling / Q000379:methods; D013778:Tetrazolium Salts / Q000378:metabolism
D000890:Anti-Infective Agents; D006601:Hexoses; D011140:Polyurethanes; D013778:Tetrazolium Salts; D002563:Cerium; D005707:Gallic Acid; D048271:Chitosan; C093412:hamamelitannin