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The Effects of Lysol on Living
Bacteria
Final Platform Presentation
Ashley Pruitt
Undergraduate Student
Health Science Biology concentration
Department of Biology
Tennessee Technological University
Cookeville, TN 38505
Introduction
• Known fact: Lysol kills 99.9% of living bacteria.
• Can this be proven?
• If an actual experiment tested this, will there actually be no or
almost no bacteria on an item after being treated with Lysol?
• Other similar studies had been performed and results differed.
• The results differed due to substrate and disinfectant used.
• This prompted my curiosity of Lysol and its effects.
Introduction (continued)
• Only Lysol and one other disinfectant completely inactivated
antibiotic-resistant and –susceptible bacteria (Rutala et al 2000).
• Lysol was effective in inactivating poliovirus (Lee et al 2007).
• This study showed that commercial disinfectants are not
effective on Bacillus subtilis (Sagripanti and Bonifacino 1999).
• Only two of the six disinfectants proved to actually have any
effect on killig bacteria (Acosta-Gio et al 2005).
• Another study again tested only Bacillus subtili; results inhibited the growth for a short amount of time (Williams and
Russell 1993).
Objective/Hypothesis (null)
• Objective: test effects of Lysol on bacteria.
• Alternate Hypothesis: fewer bacteria on the
Lysol-treated objects.
• Null: no difference in the amount of bacteria
before and after being treated with Lysol.
Method
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Collected samples
Transferred samples to TSA plates
Cleaned items properly
Sprayed items with Lysol
Waited 10 minutes (as directed by Lysol’s intructions.
Collected samples & transferred to plates
Incubated Plates for 24 hours
Counted bacteria & compared effects of Lysol
Ran t-test - statistical method:
(http://www.socialresearchmethods.net/kb/stat_t.php)
Materials
• TSA plates
• Sterile cotton swabs
• Can of Lysol
• Items to test + reference
• Incubator
Pictures – Item 1:
Doorknob
Item 2: Floor
Item 3- Trash Can
Results
The number of bacteria present - shown in Table
2.b.
Table 2.b. Matrix for the Effects of Lysol on Living Bacteria
Bacteria
Count
Bacteria
Count
Bacteria
Count
Items:
Before Lysol
After Lysol
Total
Bacteria
Count:
1-mean
5.33
0
5.33
2-mean
>100
0
>100
3-mean
11.33
2
13.22
4-mean
(reference)
0
0
0
Results
Difference in amount of bacteria both before and after treated
with Lysol is shown in Figure 1.
Number of Bacteria
100
90
80
70
60
50
40
30
20
10
0
1
2
Different Items
3
Figure 1. Amount of Bacteria Present Before and After Being Treated with
Lysol
Discussion
• Results agreed with the studies by Rutala (2000) and Lee
(2007), saying that Lysol did have a major effect on
bacteria.
• Results disagreed with the studies by Sagripanti and
Bonifacino (1999), Acosta-Gio (2005), and Williams and
Russell (1993).
• The only item that bacteria remained on was the trash can.
• Explanation: 1) The surface of the trash can has crevices
and small places for bacteria to hide in while it was being
treated with Lysol. 2) More bacteria had time to infect to
the treated area before the sample was taken
• Lysol WAS effective on killing living bacteria.
• Lysol lived up to its claim.
Conclusion
• Null hypothesis was rejected by results of ttest.
(Null: no difference in the amount of bacteria
before and after being treated with Lysol.)
• Alternate hypothesis was accepted:
THERE WAS LESS BACTERIA AFTER
BEING TREATED. SO, THERE WAS A
DIFFERENCE IN THE AMOUNT OF
BACTERIA PRESENT BEFORE AND AFTER
BEING TREATED WITH LYSOL.