Transcript Mouthwash Effectiveness in Eliminating Bacteria

Mouthwash Effectiveness in
Eliminating Bacteria
By: Matthew Mancuso
Department of Biology
Tennessee Technological University, Cookeville, TN 38505
Overview
Introduction
 Background
 Hypothesis
 Materials, Methods, and Data Collection
 Timelines
 Expected Results
 Benefits

Introduction
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
This will test the effectiveness of
several kinds of mouthwash which
claim to be antibacterial: Scope®,
Listerine®, and Cepasol®.
Against several common strains of
bacteria found in the mouth: Genus
Streptococcus, Bacillus, and
Pseudomonas.
Objective

To determine if commercially available
mouthwashes are capable of
performing the advertised elimination
of common oral bacteria.
Experimental


Tests will be run both with dilutions of the
mouthwash samples in tubes, and streak
plates with discs treated with mouthwash.
These will determine the strength of the
antimicrobial agent in the mouthwash, as
well as its ability to inhibit formation of new
bacterial colonies.
Expectations


All 3 brands contain alcohol, which is
effective in killing bacteria in solution, the
tubes should show a correlation between
alcohol % and ability to eliminate bacteria.
On the plates the alcohol will evaporate
leaving only the antibacterial agents to slow
the growth of bacteria, these will show the
strength of the other antimicrobial agents in
the mouthwash.
Background
Data recorded in these tests should
correlate with other studies on similar effects
of mouthwashes.
 These include dilution tests which suggest
the effectiveness of alcohol, as well as
active ingredient tests.

Journal Sources
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“The Effect of Mouthwash on the Bacteria Found in the Mouth Over a
Period of Time.” Dana A. Blackburn (Bulletin of the South Carolina
Academy of Science, Annual 2003)
“The Role of Therapeutic Antimicrobial Mouthrinses in Clinical Practice.”
Michael L. Barnett. (Journal of the American Dental Assoc, June 2003 )
“Effects of a Chlorhexidine Gluconate – Containing Mouthwash on the
Vitality and Antimicrobial Susceptibility of In Vitro Oral Bacterial
Ecosystems.” Robert G. Bartolo; Andrew J. McBain; Carl E. Catrenich;
Duante Charbonneau; Ruth G. Ledder; Peter Gilbert. (Applied
Environmental Microbiology Aug. 2003)
“The Antimicrobial Effect of Mouth Rinses When Used for 15 Seconds.”
Darcie Bell; Laura Bretsch; Michael Lents; James D Kettering. (Journal
of Dental Hygiene, Fall 2000)
Hypothesis

Antimicrobial mouthwashes are effective
at killing bacteria but not as effective as
the product labeling suggests.
Materials: Plates
Bacteria: Millions of each, Streptococcus,
Pseudomonas, and Bacillus, bacteria
commonly found on food and in the mouth.
Agar plates: 12, one for each type of
bacteria/mouthwash pairing and 3 for
control.
Testing discs: (60)5 per plate, this will give
many sets of data for each mouthwash
while not wasting plates.
Methods: Plates
Each of the 3 species
of bacteria will be
cultured in broth then
applied in streaks to
agar plates so the
bacteria are evenly
distributed about the
surface.
Methods: Plates
Discs soaked in each
of the different
mouthwashes will
then be applied to the
agar plates (1 type
per plate), and discs
soaked in water will
be applied to the
control.
Methods: Plates
After the bacteria is
allowed to incubate
for several days the
zones of inhibition
(area around the
discs where no
bacteria is growing)
will be measured.
Methods: Plates
The size of the zone corresponds to the ability of
the antimicrobial agent in the mouthwash to
inhibit the growth of bacteria.
Data Collection: Plates
Bacillus
Agar Plate Results
Inhibition radius in mm from disc
Disc #
1
Scope
Listerine
Cepasol
Control
2
3
4
5
Materials: Tubes
Test tubes:60, for each of the 3 mouthwash to be
mixed at each of 5 dilutions (1, 1:1, 1:10, 1:100,
1:1000) and each to be paired with the 3 different
bacteria, and 15 for the control, a dilution of
common laboratory antiseptic to which the results
may be compared .
Broth: nutrient broth to be used in each of the test
tubes as the diluting agent.
No other lab equipment will be necessary, as
results will be immediately visible to the naked eye.
Methods: Tubes
The first test tube of
each dilution is first
filled with 110mL of
the pure mouthwash.
The 4 subsequent
tubes are filled with
90mL of broth.
Methods: Tubes
10mL of liquid is then
removed from the 1st
tube and placed into
the 2nd, making this
mixture 1/10 as
strong as the original,
this is continued from
the 2nd to the 3rd, 3rd
to the 4th, and 4th to
the 5th.
Methods: Tubes
After a few days each tube will be examined to
determine if bacteria are growing in it, typically
indicated by sediment and cloudiness of the broth.
Then the lowest concentration of mouthwash with
no bacteria growing in it can be compared to the
control to determine the strength of the
antimicrobial agents in each type.
Data Collection: Tubes
Bacillus
Test Tube Results
Bacteria present (pos. or neg.)
Dilution
1
Scope
Listerine
Cepasol
Control
1/10
1/100 1/1,000 1/10,000
Timelines
Preparation of each set of tests should
take less than 1 day.
 Incubation should be run for 2 or 3 days to
be sure maximum growth has occurred.
 Examination of the results should take less
than 1 day as well.
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Expected Results
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It is expected to see a correlation between
alcohol % and bacteria killed in solution as
alcohol is a known antimicrobial.
Results from the various antiseptics in the
products should vary as the effectiveness of
these specific chemicals on the bacteria may be
different, though it is expected that Listerine,
having more antimicrobial substances should
prove more effective than the other 2.
Benefits

This research should help a person to
decide what mouthwash to purchase
based upon its contents and not just the
claims listed on the bottle.