The Effect of Antibacterial and Non-Antibacterial Hand Soap on the Amount of Bacteria on the Hands

Photo of Researcher

Researched by Joseph R.
2005-06




PURPOSE

The purpose of this experiment was to compare the effect of anti-bacterial and non-anti-bacterial hand soap on the amount of bacteria on the hands.

I became interested in this idea when I was watching television and I saw ads for hand soaps that said they killed 99.9% of bacteria after washing your hands. I also wondered why my mom was so concerned about people washing their hands.

The information gained from this experiment could help doctors, nurses, parents, and children. No one wants to get sick! It is important to protect people from diseases.


HYPOTHESIS

My first hypothesis was that anti-bacterial hand soap would remove more bacteria than non-anti-bacterial hand soap.

My second hypothesis was that non-anti-bacterial hand soap would remove at least 50% of bacteria from the washed hands.

I based my hypotheses on a Compton’s Encyclopedia article on bacteria which said that one bacterium could produce over 1,000,000,000 more after 24 hours, and that not one hand soap could remove all bacteria from your hands.

 
EXPERIMENT DESIGN

The constants in this study were:
•    The amount of time spent washing hands
•    The motion of washing hands
•    The approximate strength used to wash hands
•    The amount of hand soap used (2 ml.)
•    The temperature of the water
•    The pressure of the water
•    Time incubating
•    The temperature of the incubator
•    The number of blood agar plates used to culture bacteria

The manipulated variable was the type of hand soap: Anti-bacterial vs. Non-Anti-Bacterial

The responding variable was the number of colonies of bacteria on agar plates after being inoculated with samples from the hands.

To measure the responding variable, I counted the colonies of bacteria on the plates after they were incubated for 24 hours  


Materials

QUANTITY ITEM DESCRIPTION
42
sterile swabs
1
bottle of anti-bacterial hand soap
1
bottle of non-anti-bacterial hand soap
1
incubator
2
lab coats
2
pairs of gloves
24
blood agar plates


 
PROCEDURES

1.    Gather the signed permission slips
2.    Get the materials
3.    Obtain the subjects
4.    Swab the subject’s left hand (5 times in a left/right direction, 5 times in an     upward/downward motion)
5.    Put swab away in bag marked with subject’s number and hand (L/R)
6.    Repeat steps 4,5 on the rest of the subjects
7.    Show the subjects the method to wash their hands (10 seconds on the top, 10 seconds on the palm, 10 seconds between the fingers, 10 seconds rinsing)
8. Have the subjects’ wash their hands with anti-bacterial hand soap in water, under the same  sink  
9.    Swab the subject’s right hand (5 times in a left/right direction, 5 times in an upward/downward motion)
10.     Repeat step 5  
11. Repeat steps 4-10 with non-anti-bacterial hand soap
12.    Rub/twirl one swab onto one blood agar plate in an up/down motion
13.     Turn the plate 45 degrees
14.     Repeat steps 11 and 12 for each bag, with same label as the bag
15.     Place blood agar plates into the incubator for 72 hours
16.     Come back to the hospital in 72 hours
17.     Take blood agar plates out of incubator
18.     Count colonies with naked eye under a white light
19.     Record data

 
RESULTS


The original purpose of this experiment was to determine the effect of antibacterial and non-antibacterial hand soaps on the amount of bacteria on the hands.

The results of the experiment were that the non-antibacterial soap removed more bacteria than the antibacterial soap.  Also, the non-antibacterial hand soap did remove more than 50% of the bacteria.


See the table and graph below.


CONCLUSION

My first hypothesis was that anti-bacterial hand soap would remove more bacteria than non-anti-bacterial hand soap.
 

The results indicate that this hypothesis should be rejected, because the amount of bacteria on the blood agar plates with antibacterial soap was greater than the plates with non-antibacterial testing.

My second hypothesis was that non-anti-bacterial hand soap would remove at least 50% of bacteria from the washed hands. This hypothesis should be accepted.


After thinking about the results of this experiment, I wonder if different brands would change the results of this experiment. I also wonder if the amount of time spent washing would reduce more bacteria.

If I were to conduct this project again, I would test a different brand of soap, and try to see which active ingredient removed more bacteria.

 

RESEARCH REPORT

Introduction to Bacteria

Bacteria are one celled, microscopic organisms that can only be seen alone with the aid of a microscope. They can fit on the point of a pin. Also, bacteria can reproduce over 1,000,000,000 in just 24 hours.

Structure

Nearly all bacteria are protected by a cell wall. Bacteria also may have up to three protective layers. Flagella are microscopic hairs on the bacteria that help them move with a whip-like motion. Bacterial spores may live for more than a decade. The capsule makes the cell resistant to any destructive chemicals.

Some shapes of bacteria are bacilli, cocci, vibrios, and spirochetes. Bacilli are rod shaped bacteria. Cocci are spherical bacteria.  Vibrios are rod shaped bacteria, and spirochetes are long, slender, tightly coiled bacteria.

For bacteria group names, “strepto” means chain. “Staphlo” means cluster, and “diplo” means pair.

Bacteria can move in air currents, water, clothing, utensils, food, and on other objects.

Bacteria in Foods

In improperly canned foods, bacteria can form a food poisoning called botulism, caused by toxins. Botulism is a threat to human health, which can cause sickness and death. When frozen food becomes thawed, bacteria come active again. Also, cheeses owe their flavor to many kinds of bacteria.

History of Bacteria

The first living things were probably bacteria. In the mid-1670’s, Anton van Leeuwenhoek discovered bacteria. Bacteria are in and on practically everything.


Helpful Bacteria

Certain kinds of bacteria are needed for a human body to live. For example, some bacteria help in digestion, destroy harmful organisms, or even produce vitamins needed for the body. Also, bacteria play a role in recycling carbon, nitrogen, sulfur, and other chemical elements.

Harmful Bacteria

Some bacteria can be harmful to the body also. Some cause cholera, gonorrhea, leprosy, pneumonia, syphilis, tuberculosis, typhoid, fever, and whooping cough. Bacteria will enter the nose, mouth, or through breaks in the skin.

Aerobes and Anaerobes

Aerobes are bacteria that require oxygen to survive. On the other hand, anaerobes do not require oxygen to survive, and some are even killed by oxygen.

Hand Soaps

In hand soaps, the active ingredient is usually triclosan. Triclosan damages cell walls of bacteria, slowing their growth so that they eventually will die.

Summary

As you can see, bacteria are microscopic organisms that we don’t always stop to think about that can be useful or harmful. Humans would not survive without bacteria, but we can also not survive from them.

BIBLIOGRAPHY


“Bacteria.” Compton’s by Britannica. December 1, 2003. http://elibrary.bigchalk.com/libweb/elib/do/document

“Bacteria” http://www.microbe.org/microbes/bacterium1.asp

Clark, Marie. Personal Interview. 1/16/06

Facklam, Howard and Margery. Bacteria. New York: Henry Holt Company Inc. 1994, pp. all

Fickes, Rachel. “The Effects of Antibiotics on Bacterial Growth” Selah Science Projects 2001 http://www.selah.k12.wa.us/SOAR/SciProj2001/RachelF.html
 
Schlessinger, David.  "Bacteria.” World Book Encyclopedia, 1999.
 


ACKNOWLEDGEMENTS

      I would like to thank the following people for helping make my project possible:

•    My parents for taking me to the hospital lab to set up times to do the experiment and times to prepare the blood-agar plates with the swabs. Also for encouraging me and being willing to take some time off of work to take me places for my experiment when I needed to.

•    All of my friends in SOAR for volunteering to be subjects for my experiment.

•    Mr. Newkirk for being the best science teacher that he could be. Also for working to correct my report.

•    Marie Clark for helping me with my experiment, signing all of my safety hazard forms, and most of all, letting me come into the microbiology laboratory.

•    Mrs.Viernes for helping me with all of my formatting and computer problems.

     wigidi-wigidi-wack


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