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EFFECT OF SILVER COATED THREAD
ON THE
MICROBIAL POPULATION OF SHOES
The
purpose of this project was to
determine the effects of
silver-coated thread on the
indigenous population of
microorganisms in the shoes worn
by diverse people. Interest in
the project developed from our
previous studies, from which we
found that silver-coated thread
was remarkably inhibitory to the
growth and reproduction of
several human pathogenic
bacteria.
We
reasoned that silver-coated
thread incorporated into
insertable shoe pads or the
textile lining of shoes might be
inhibitory to bacteria and other
microorganisms found in those
shoes worn by people. As most
foot odors result from the
metabolic products of
microorganisms growing on the
human foot or in the shoe
itself, use of silver-coated
thread in shoes might also
dramatically reduce these odors.
Various sizes of Dr. Scholl’s
Air-Pillo® Double Comfort
Insoles (foot pads) were
purchased commercially. A
lightweight cloth woven with
silver-coated thread was
pressure laminated to the bottom
surface of the footpad for the
right foot. A non-silver
containing cloth of the same
weight was pressure laminated to
the bottom surface of the foot
pad for the left foot and served
as the experimental control.
At
the beginning of each
experimental test, both the left
and right shoes of nine
volunteers were swabbed in the
area of the “ball of the foot”
with cotton swabs previously
soaked in a solution of
physiological saline. Each swab
was immediately dropped into 4.5
ml of physiological saline
solution and vigorously mixed
for 30 seconds. The resulting
mixture was seriously diluted in
brain heart infusion (BHI broth
and each dilution was plated in
BHI agar in Petri dishes.
Each
plate was then incubated at 37°C
(the physiological temperature
of people) for 48 hours. The
total number of colonies from
each dilution plate was counted
and used to determine the number
of microorganisms present in the
undiluted sample.
After seven days of simultaneous
wear of both control and silver
containing foot pads the above
procedure was repeated. The
total number of microorganisms
at time zero and at seven days
wear were compared (see Figure
1).
The
number of microorganisms in the
control shoe (left foot pad
without silver-coated cloth)
increased by an average of 11.8%
during seven days of wear while
the number of microorganisms in
the test shoe (right foot pad
containing silver-coated cloth)
decreased by and average of 88%.
A
subjective test of odor
indicated a greatly diminished
odor in the right shoe.
Obviously, the presence of
silver in the right shoe of the
volunteers greatly diminished
the total count of
microorganisms and their
associated odors.
S.E.
Stevens, Jr. and Robert Boor
Department of Molecular and Cell
Biology
The Pennsylvania State
University
University Park, Pennsylvania
16802
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