Center for Biofilm Engineering
Abstract:
"Electrical Enhancement of Streptococcus gordonii Biofilm
Killing by Gentamicin"
00-007 This electrical enhancement was demonstrated in an in vitro
model. Streptococcus gordonii biofims were grown for 6 days in
continuous-flow reactors on one-tenth strength trypticase peptone broth. The
biofilms attained a mean areal cell density of 2.4 x 108 c.f.u./cm2
and a thickness of approx. 19 : m. Biofilms exhibited characteristic resistance
to killing by an antibiotic. When treated with 2 : g/ml gentamicin for 24 h,
they exhibited a 0.84 log reduction in viable cell numbers; a 4.7 log reduction
was measured in a planktonic culture. Killing of planktonic bacteria by this
treatment was reduced to 1.2 log when an oxygen-scavenging enzyme was added to
the medium. When a 2-mA direct current was applied during antibiotic treatment,
biofilm killing increased to a 4.3 log reduction. Electrical current alone
caused a 1.9 log reduction in biofilm cell counts. It is suggested that
gentamicin was less effective against S. Gordonii under anaerobic
conditions than it was under aerobic conditions and that this can explain both
the reduced susceptibility of the biofilm (due to oxygen depletion) and
electrical enhancement of efficacy (due to oxygen generation by electrolysis).
Wattanakaroon, W., and P.S. Stewart,
"Electrical Enhancement of Streptococcus gordonii Biofilm Killing by
Gentamicin," Archives of Oral Biology, 42:167-171 (2000).
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