Interference in adhesion of bacteria and yeasts isolated from explanted voice prostheses to silicone rubber by rhamnolipid biosurfactants.
OBJECTIVE
The effects and extent of adhesion of four different bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber with and without an adsorbed rhamnolipid biosurfactant layer obtained from Pseudomonasaeruginosa DS10-129 was studied.


RESULTS
The ability of rhamnolipid biosurfactant to inhibit adhesion of micro-organisms to silicone rubber was investigated in a parallel-plate flow chamber. The anti-adhesive activity of the biosurfactant at different concentrations was significant against all the strains and depended on the micro-organism tested. The results showed an effective reduction in the initial deposition rates, and the number of bacterial cells adhering after 4 h, for all micro-organisms tested at the 4 g l(-1) undiluted rhamnolipid solution. Maximum initial reduction of adhesion rate (an average of 66%) occurred for Streptococcus salivarius GB 24/9 and Candida tropicalis GB 9/9. The number of cells adhering after 4 h on silicone rubber conditioned with biosurfactant was reduced to 48% for Staphylococcus epidermidis GB 9/6, Strep. salivarius GB 24/9, Staphylococcus aureus GB 2/1 and C. tropicalis GB 9/9 in comparison to controls. Perfusing the flow chamber with biosurfactant containing solution followed by the passage of a liquid-air interface, to investigate detachment of micro-organisms adhering to silicone rubber, produced high detachment (96%) of adhered cells for all micro-organisms studied, except for Staph. aureus GB 2/1 (67%).


CONCLUSIONS
It is concluded that biosurfactant represent suitable compounds that should be considered in developing future strategies to prevent the microbial colonization of silicone rubber voice prostheses.
Centro de Engenharia Biológica, Universidade do Minho, Campus de Gualtar, Braga, Portugal.
L R
LR
Rodrigues
I M
IM
Banat
H C
HC
van der Mei
J A
JA
Teixeira
R
R
Oliveira
D000191:Actinomycetaceae / Q000187:drug effects / Q000502:physiology; D001422:Bacterial Adhesion / Q000187:drug effects*; D002176:Candida albicans / Q000187:drug effects / Q000502:physiology; D041022:Candida tropicalis / Q000187:drug effects / Q000502:physiology; D015169:Colony Count, Microbial / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006017:Glycolipids / Q000494:pharmacology*; D006801:Humans; D007831:Larynx, Artificial / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000737:chemistry; D012826:Silicone Elastomers; D013211:Staphylococcus aureus / Q000187:drug effects / Q000502:physiology; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000502:physiology; D013291:Streptococcus / Q000187:drug effects / Q000502:physiology; D013500:Surface Tension; D013501:Surface-Active Agents / Q000494:pharmacology*; D015003:Yeasts / Q000502:physiology*
D006017:Glycolipids; D012826:Silicone Elastomers; D013501:Surface-Active Agents; C418382:rhamnolipid