Bacterial Growth on Public Restroom Toilet Seats vs. Bacterial Growth on Public Restroom Door Handles: A Microbiological Approach

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Bacterial 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

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Introduction

• 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).

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Introduction (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).

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Introduction (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).

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Introduction (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).

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Introduction (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)

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Introduction

• 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).

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Objective/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

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Methods 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

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Methods 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

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Results

• 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.

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Results (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
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Results (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)
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Results (contd)
Figure 1 Bacterial Growth Colony Counts Toilet
Seats vs. Door Handles
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Results (contd)
Figure 2 Picture of bacterial growth from one of
the sites tested
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Results (contd)
Figure 3 Bacterial growth at another site
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Results (contd)
Figure 4 Bacterial growth at another site
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Discussion

• 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.

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Discussion (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.

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Discussion (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.

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Discussion

• 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.

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Discussion (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.

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Discussion (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.

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Discussion (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.

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Conclusions

• 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.

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Conclusions

• 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.

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Conclusions

• 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.

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Conclusions

• 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.

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??Any Questions??