Title: Bacterial Growth on Public Restroom Toilet Seats vs. Bacterial Growth on Public Restroom Door Handles: A Microbiological Approach
1Bacterial Growth on Public Restroom Toilet Seats
vs. Bacterial Growth on Public Restroom Door
Handles A Microbiological Approach
- Jamie J. Larsen
- Undergraduate Student (Biology Concentration)
- Department of Biology
- Tennessee Technological University
- Cookeville, TN 38505
2Introduction
- People have come to desire information that would
tell them how to disinfect particular areas
(Ojima et al 2002). - No one has yet used uniform sampling conditions
to derive bacterial count distributions (Ojima et
al 2002).
3Introduction (contd)
- The accumulation of this data would lead to
research that could contribute to the estimation
of infection risks for communicable diseases
(Ojima et al 2002). - Flushing of a toilet produces bacteria-laden
aerosols which settle on the toilet and bathroom
surfaces (Rusin et al 1998).
4Introduction (contd)
- Bathroom sites such as the toilet bowl surface,
flush handle, and floor are often contaminated
with E. coli and other coliforms due to direct
transmission from flushing of the toilet (Rusin
et al 1998). - Many enteric pathogens are spread by the
fecal-oral route and it has been suggested that
the fallout of droplets containing fecal
material, after flushing the toilet, is an
important infection hazard within the bathroom
(Barker and Jones 2005).
5Introduction (contd)
- Another infection hazard in bathrooms is the
decreased number of people who wash their hands. - Handwashing is one of the most important factors
in controlling the spread of bacteria and in
preventing development of infections (Guinan et
al 1997).
6Introduction (contd)
- Viruses can also be transferred due to contact
with public restroom surfaces. - Viruses can survive on inanimate objects, but
their transfer and survival on hands also plays a
part in their transmission (Bellamy et al 1998)
7Introduction
- With the data obtained from studies on bacterial
growth on public restroom surfaces it would be
possible to promote the general publics
understanding of sanitation issues and facilitate
the provision of useful information and products
(Ojima et al 2002).
8Objective/Hypothesis
- Objective
- Determine which surface contained the most
bacterial growth - Hypothesis
- Public restroom toilet seats will contain the
most bacteria - Null Hypothesis
- Both the toilet seats and the door handles will
contain the same amount of bacteria
9Methods and Materials
- Materials (Goss 2006)
- Data Form
- 10 agar plates (divided in half)
- Sterilized cotton swabs
- Gloves
- Distilled Water
- Permanent Marker (to label plates)
- Incubator
10Methods and Materials (contd)
- Methods (Goss 2006)
- Swabbed toilet seats and door handles in ten
public restroom sites - Cleaned one site with bathroom cleaner
- Labeled/Streaked the agar plates
- Incubated for 48 hours
- Checked growth, did colony counts, and analyzed
results using the t-test statistic
(http//iweb.tntech/cabrown/Ecology20labs/t-tests
.doc) - Repeated experiment
11Results
- Even though two runs of the experiment were
conducted, each produced similar results so
therefore only data obtained from the first
experiment was used in interpretation of the
results. - Sample size9 not 10 due to too much growth on
one of the plates.
12Results (contd)
Table 1 Bacterial Growth Colony Counts (Run 1)
Colony Counts Colony Counts
Sample Toilet Seats Door Handles
1 0 6
2 52 11
3 84 13
4 100 14
5 0 15
6 50 2
7 0 12
8 10 35
9 100 19
TOTAL 396 127
13Results (contd)
Table 2 T-test Results
Toilet Seats Door Handles
Mean (X) 44 14.1
Variance (s2) 1867 86.11
Sample Size (n) 9 9
T-test Statistic 2.13 (2.13gt2.10, reject null) 2.13 (2.13gt2.10, reject null)
14Results (contd)
Figure 1 Bacterial Growth Colony Counts Toilet
Seats vs. Door Handles
15Results (contd)
Figure 2 Picture of bacterial growth from one of
the sites tested
16Results (contd)
Figure 3 Bacterial growth at another site
17Results (contd)
Figure 4 Bacterial growth at another site
18Discussion
- Since it was found that public restroom toilet
seats contained the most bacterial growth, it
seems that bacteria-laden aerosols do tend to
settle more on the toilet seats rather than on
the door handles. (t-test2.13gt2.10, Table 2) - This then contributes to higher bacterial growth
colony counts.
19Discussion (contd)
- Barker and Jones (2005) found that both the
bacteria attached to the sidewalls and those
present in the bowl water contribute to the
aerosol formation. - This then exemplifies the amount of
bacteria-laden aerosols that settle on the
surface of the toilet seat and therefore it can
be easily seen why it was found that there is
more bacterial growth on public restroom toilet
seats.
20Discussion (contd)
- Another study done by Stuart and Jones (2006), in
which they sampled steel push plate door handles
at a University, found that while staphylococci
could be isolated from some of the restroom push
plates, the total numbers were very low and
included no isolates of S. aureus. - This shows that even though the bathrooms tested
were found in an area where people regularly use
them throughout the day the researchers were
unable to isolate any bacteria from them.
21Discussion
- A study done by Bellamy (et al 1998) found that
hemoglobin, indicating the presence of blood and
therefore possible contamination of surfaces with
blood-borne viruses, was found on toilet bowls
and toilet seats. - Bellamy (et al 1998) also goes on to say that
these surfaces are frequently handled and could
therefore play a part in viral transmission.
22Discussion (contd)
- This study agrees with the results of my study in
that contact with a public restroom surface that
is not thoroughly disinfected could lead to
transmission of bacterial and viral infections.
23Discussion (contd)
- The results of my research, however, disagree
with the results of Rusin (1998) in which it was
determined that the toilet seat was the cleanest
site tested. - However, Rusin (1998) goes on to say that this
may be due to regular disinfection of the toilet
and therefore results in lower levels of
bacterial growth.
24Discussion (contd)
- Another study that disagrees with my findings is
a study done by Ojima (et al 2002) in which they
found that coliforms and E. coli were not found
on toilet bowl rims and that the contamination
level for toilets was the lowest of the study. - Ojima (et al 2002) goes on to say that this could
also be due to regular disinfection at the sites
tested.
25Conclusions
- Reject null hypothesis
- T-test2.13gt2.10 (Table 2)
-
- Accept hypothesis
- There is more bacterial growth on public restroom
toilet seats than on public restroom door
handles. - Bacteria-laden aerosols do contribute to the
increased amount of bacteria found on the toilet
seats.
26Conclusions
- Bacteria-laden aerosols tend to settle more on
the toilet seat rather than on the restroom door
handles. - I hope that more studies can be done on the
amount of bacterial growth on environmental
surfaces.
27Conclusions
- I think a good area of research would be on, not
only the amount of bacteria found on public
restroom surfaces, but also the types of bacteria
found on public restroom surfaces. - I would also recommend research to be done on
exactly what types of bacteria found on public
restroom surfaces are problematic.
28Conclusions
- I hope that the results of this experiment help
to educate the public about the amount of
bacteria found in public restrooms. - I believe that by knowing this information,
people will become better aware of their
surroundings and improve their personal hygiene
in public restrooms.
29??Any Questions??