Which Waterless Hand Sanitizer Is Most Effective in Killing Bacteria?
  Researched by Sonia T.
2001-02



PURPOSE

The purpose of this experiment was to determine which type of waterless hand sanitizer would kill germs most effectively. 

I became interested in this idea when I learned about diseases caused by E.coli and wondered what people should use to help prevent such diseases caused by dirty hands. 

The information gained from this experiment may be used by all people, especially parents of young children, so that they know the best type of waterless hand cleansers to use to help prevent diseases. 




HYPOTHESIS

My hypothesis is that the hand sanitizers with highest percentage of ethyl, or isopropyl alcohol will be more effective killing bacteria on average.  Based on this information, I think that the Lysol brand will be the most effective on killing germs because of the higher percentage of alcohol.

I base my hypothesis on a July 2000, hospital infection control article which states that "the higher amounts of alcohol up to 70%, the better the hand cleanser kills bacteria."(John M. Boyce)

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 EXPERIMENT DESIGN

The constants in this study were:

  •  Amount of water used (none)
  •  New bottle of each type of hand cleanser. 
  •  The amount of hand sanitizer on the hands (1 ml.)
  •  The place on the hands you wash 
  •  Amount of time spent washing the hands (ten seconds)
  •  The motion used washing the hand
  •  The method of judging the amount of germs on the hands after they’re washed
  •  The amount of time after you’re hands are washed before taking the sample 
  •  Size of the area you wash determined by template 
  •  The type of swab used to collect the germs
  •  The motion and method of collecting the germs
  •  The time spent taking the sample (ten seconds)
  •  The shape of the area you take the sample
  •  The type of material of the template
  •  The type of agar and size of plate used to grow the bacteria in
  •  Method of applying germs to agar
  •  The area the germs are spread on the agar plate
  •  The same subject before and after use of gel
  •  The time the germs grow in the incubator
The manipulated variable was the type of hand sanitizer.

The responding variable was the percentage of bacteria still living after using the hand gel.

To measure the responding variable will count the number of living bacteria in the past experiment, and compare it with the number of living bacteria in the pre experiment. I will do this with all brands of gel, to see which one killed the most bacteria.

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MATERIALS
 

QUANTITY

ITEM DESCRIPTION
10 Subjects
Hand Sanitizer
100 Blood Agar plates
100  Hand coverings (templates)
100  Sterile swabs
 Incubator
 Stopwatch

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PROCEDURES

1. Gather the materials.
2. Obtain the subjects.
3. Teach the method of hand washing to the subjects (six seconds on the top of the hands, six seconds on the palm of the hands, and six seconds in between the fingers).
4. Place the swabbing template (hand covering) over the left hand.
5. Take the sample with the sterile swab.
6. Take the swabbing template off the hand.
7. Take the number one hand gel, and apply 1 milliliter of it to the palm of the hand.
8. Wash the hand for fifteen seconds in the above-directed manner.
9. Put a new template on the opposite hand.
10. Repeat step number five.
11. Repeat steps three through nine with nine other subjects.
12. Repeat steps three through ten with all of the other gels, labeling each sample carefully.
13. Take the samples to the Memorial Hospital lab.
14.  Transfer the bacteria onto the agar plate dishes by rolling the swab across the plate in three directions to spread a uniform inoculum over the agar plate 
15. Incubate the bacteria.
16. Return to the hospital in forty-eight hours.
17. Count the number of germs in the first sample still living, in each subject’s sample.
18. Count the number of germs in the second sample of each subject.
19. Figure out the percentage of bacteria killed, after using each type of the hand sanitizers.
20. Sterilize all agar plates and other materials and kill all germs by autoclave.

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  RESULTS

The original purpose of this experiment was to determine which type of waterless hand cleanser would kill germs most effectively.

The results of the experiment were that the three soaps had no significant difference, although the Purell brand of hand sanitizer with a 62% of ethyl alcohol as it’s active ingredient l worked the best. The Lysol brand of hand sanitizer with 63% ethyl alcohol as it’s active ingredient had the least amount of bacteria killed. 

See the data and graphs




 CONCLUSION

My original hypothesis was that the hand sanitizers with highest percentage of alcohol would be more effective killing bacteria on average. I thought that the Lysol brand would be the most effective killing germs because of the higher percentage of alcohol.

The results indicate that this hypothesis should be rejected because I predicted that the Lysol brand of hand sanitizer with 63% percent alcohol as it’s active ingredient would kill the most bacteria, but the Purell brand with 62% alcohol as it’s active ingredient did the slightly better. 

Because of the results of this experiment, I wonder if I would get the same results if I were to use different brands with the same alcohol percentage. I also wonder if I had changed my procedures and gone about doing my experiment in a different method, would I have gotten the same results.  For example, I could have collected the germs differently or even applied them to the agar plates differently.

My findings should be useful to the public, because these hand washes are significant in reducing bacterial counts. These would be useful to a number of different people such as parents of young children, elderly people, people with health concerns, people who work in a high bacterial environment, people who people who prepare food, and people with no water convenient to them. 

If I were to conduct this project again, I would make many changes. 
 

  • The most important change I would have to make would be to change my procedures. I would have grown the bacteria on an agar plate. If I would have done this, I would know that my information was accurate. 
  •  Another thing I could do would be to take both of the bacteria samples off of the same hand. 
  •  I would also have done a more advanced technique when I apply the germs to the agar plate because something may have gone wrong when I was applying the germs to the plates. 
  • Another change I would make would be more variations in the soaps I used. Instead of using three different soaps, I would use six. If I could not find any more variations in the alcohol percentages, I would use two soaps of each percentage. 
  • I would also do more replicas of my experiment and more trials during my experiment. 


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Research Report
"Hand washing is the number one way to prevent disease."  (Gay Scott, Infectious Disease Control ? Yakima Valley Memorial Hospital)  Historically, people have washed their hands with water, sand, animal products, sanitary wipes, bar, liquid, flake, and foam soaps.  The most recent development in hand washing products is the waterless hand sanitizer gels and sprays.  The active ingredient in these sanitizers is alcohol.  In order to determine whether waterless hand sanitizers are effective and which one is most effective, a person must study various topics.

Hand washing:

There are many parts involved in proper hand washing techniques.  Lots of time should be taken when a person washes their hands.  The way a person washes their hands is also important.  Hands should be washed in the palm areas, in between the fingers, on top of the hand, and underneath the fingernails.  It is also important to use enough pressure (friction) when rubbing hands together.

Soap:

The earliest proof, in writing, of soap being used dates back to the 3d millennium BC when references of soap were made on clay tablets found in Mesopotamia.  The earliest ingredient in soap was potash, a potassium compound made from wood ashes, and oil.  Soap is a natural cleansing material.  Soaps are manufactures for personal hygiene and household cleaning purposes.  During hand washing, physical and chemical processes occur.  The general explanation of how soaps works is that their surfactant s (surface active agents) attract water molecules.  Other ingredients do not attract water.  Surfactants improves the water’s ability to loosen soil.  Other molecules surround and lift dirt particles until they are rinsed away.

Bacteria:

Bacteria are one of the many harmful germs throughout the body and in the environment. Other types of germs besides bacteria are viruses, fungi, protozoans, and parastic worms. Germs and bacteria are almost everywhere in the world. Bacteria are kept out of the body by an oil that the body produces. These oil glands are located all over the body, though there are none found on the palms of the hands and the soles of the feet. These glands produce an oil called sebum. It keeps the skin from getting infectious diseases by keeping large amounts of bacteria out of your body. 

Bacteria gets into the body when there is an open wound or an open patch of skin. When a knee is scraped and a person has an open wound, it gives bacteria a chance to come directly into the body. When looking under a microscope, bacteria can be seen. The can be shaped spherical, like rods, and in spirals. Many diseases are caused by germs. In the following paragraphs, some common but deadly diseases caused by germs, will be discussed.

Tuberculoses:

Tuberculoses is an infection that usually just affects the lungs, but can also affect other organs in the body. This particular disease is caused by a rod shaped bacteria called Tubercle Bacilli. Most of the people that have it get infected when they inhale tiny droplets of moisture containing mycobacterium tuberculoses. Mycobacterium  tuberculoses is a bacteria that is transmitted when people sneeze. People can also get it by drinking milk from an animal that has it. 

" The Tracheobronchial tree is the branching system of tubes that bring air to and from tiny air sacs (alveoli) in the lungs.  It consists of the trachea (windpipe), two bronchi, and hundreds of thousands of smaller airways called bronchioles. It is lined with cells that can move the layer of mucus covering them upward.  Bacilli trapped in the mucus layer are moved up the airways toward the throat, mouth, and nose. The Bacilli may then be sneezed, spat, coughed out, or blown out. They also may be swallowed and passed harmlessly through the digestive system." (Michael E. Levitzky, World Book Encyclopedia).

Boils:

Boils, a painful disease under the skin is caused when Staphylococcus enters the skin under the hair. Boils begin looking like a hard, red, bump. In a few days, the boils’ center starts to fill up with pus. After the skin breaks, the pus drains out. After this happens, the boils start to heal. White blood cells can commonly fight the infection but sometimes they can not. The boils are most commonly found on the face, armpits, arms, and buttocks. Boils start to get smaller and reduce their size, when hot, moist, pads are placed over it. If a person tries to manually reduce the boil’s size, an infection can be caused in the blood stream.
 
 

Staphylococcus:

Staphylococcus is an organism that belongs to a group of round bacteria called cocci. Looking through a microscope, staphylococcus looks like it is growing in bunches just like grapes. They usually can be distinguished by their structure or where they grow. Pimples, boils, and impetigo are caused by staphylococcus. They are caused when it enters the body by a scrape in the skin. Other staphylococcus goes deeper into the body. This disease can be treated with antibiotics.

Cholera:

Cholera is an infection in the intestine. It is caused by a comma shaped bacterium, vibrio chaolerae. It is transmitted by water that is contaminated by feces. People get cholera by drinking this contaminated water and getting it inside their intestines. The toxins in it create a large amount of water and salt. A person that gets this disease can suffer from diarrhea. The fluid loss causes severe dehydration. The easiest way of treating this infection is by adding five grams of salt and twenty grams of sugar to every liter of water that is drunk. This treatment makes up for the loss of water.

Lyme Disease:

Lyme disease is a disease caused by bacteria found in ticks. It is caused by a bacterium called Borrelia burgdorefri. Borrelia burgdorferi infects certain types of ticks found in woodland, brushy areas, and grasslands. People and animals get Lyme disease by being bitten by a tick with Borrelia burgdorferi for at least thirty- six hours. When a person gets Lyme disease, their first symptom is getting a big rash somewhere, though many people do not get this rash. Other symptoms are fevers, headaches, and muscle and joint pain in the body.

E. Coli:

E. Coli is the term for Enterobateriaceae. The recent E. Coli strain that is especially bad for humans is E. Coli; 015:H7.  E. Coli 015:H7 is infected with a virus that is able to insert it’s own DNA into the bacteria chromosome. Vero is a toxin that that the E. Coli produces. The toxin is a protein that causes bad damage to the intestinal epithelial cells.  A person will lose water and salt.  Blood vessels will be damaged and bleeding will occur. The disease is harmful to children because they aren’t able to tolerate that much blood loss. 

Alcohol:

" Alcohol refers to a class of chemical compounds, all of which consists of chemically bonded atoms of the carbon, hydrogen, and oxygen" (Enoch Gordis). All the molecules in alcohol contain one or more hydroxyl group(s). Hydroxyl groups are specific arrangements of atoms where a hydrogen atom is bonded to an oxygen atom. Here are some specific types of alcohol. 

Alcohol Types:

Ethyl Alcohol:

Ethyl alcohol is also called ethanol.  It is the alcohol found in alcoholic beverages. Its chemical formula is CH3 CH2 OH.  Ethanol can be used to dissolve other substances in lacquers, varnishes, and stains.  It is also important in the preparation of detergents, flavorings, and fragrances.

Methanol Alcohol:

Methanol is the simplest form of alcohol. It has only one hydroxyl group. Its chemical formula is CH3 OH. Methanol was first produced from wood. Now it is produced by methane. Most of the methanol produced by methane is converted to make a chemical called formaldehyde, which is used to make plastics. Another one of methanol’s purposes is to dissolve substances. It is an important solvent in dyes, and in medicines. 

Isopropyl Alcohol:

Isopropyl alcohol is best known as the main ingredient in rubbing alcohol.  Its chemical formula is CH3 CH2 CH2 OH.  It is also an ingredient in window cleaners, toiletries, disinfectants, antifreeze, and paint remover. 

Early Experiments with Alcohol as a Disinfectant:

In 1939, an experiment was done and the data showed that cleansers containing seventy percent alcohol were most effective  at disinfecting hands. Other studies done in 1939 show that up to seventy percent alcohol types was more effective also. In the middle 1900’s, studies show that the amount of alcohol past 70% did not work quite as well. 

Microbiology and how to become a Microbiologist:

Microbiologists are scientists who study bacteria, viruses, molds, algae, yeasts, and similar organisms.  Microbiologists study the form, structure, and physiology of microorganisms, their metabolism, how they reproduce their effects on living things and physical/ chemical changes they do to our world. They do their work in laboratories, government/private facilities, and medical institutions such as hospitals.

There are two types of microbiologists. They are medical and clinical microbiologists.  Medical microbiologists diagnose, treat, and help prevent diseases. Clinical microbiologists also help treat and help prevent diseases. Their research has helped prevent diseases such as typhoid fever, influenza, measles, polio, whooping cough, and small pox. Now, microbiologists are trying to figure out a way to cure diseases like aids, cancer, cystic fibrosis, and alzheimer’s diseases. In high school, if a person would want to become a microbiologist, they would need to take courses in biology, chemistry, English, and computer science.

Conclusion:

Human health is important to the body. Antibiotics, such as the waterless hand cleansers, can help people to live longer and healthier lives.  Common people need to know what type of waterless hand cleansers to buy to help prevent diseases. 

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BIBLIOGRAPHY
 

“Antibiotics.”  December 5, 2001 available @ http://www.prairiepublic.org/features/healthworks/antibiotics/

Bark, Joseph. “Skin Disorders.” World Book Encyclopedia 1999. P.430

Boyce, John M. “Using Alcohol for Hand Antiseptics.” Infection Control and Hospital Epidemiology 

Dattwyler, Ramond J. “Lyme Disease.”  World Book Encyclopedia. 1999. P. 533 

Gordis, Enoch. “Alcohol.” World Book Encyclopedia .1999. Pp. 334-335

“Human Disease.”  Microsoft Encarta 2001. CD ROM 

Levitzky, Michael G. “Tuberculosis.” World Book Encyclopedia. 1999. Pp. 477-479

Liptzin, Yelva  Lynfeild. “Boils”  World Book Encyclopedia  .1999. P. 153

“ Microbiologists.” Career Discovery Encyclopedia.  Pp. 102-103

Nardo, Don. Germs Sandiago California. Discovery and Invention, 1991. P. 39 

Plaut, Andrew G. “Cholera.” World Book Encyclopedia.  1999. 

Schlessinger, David. “ Staphylococcus.” World Book Encyclopedia. 1996 p. 839 

Scott, Gay.  Infectious Disease Control, Yakima Valley Memorial Hospital.  Personal Interview.

“Skin Glands.” Microsoft Encarta. 2001. CD ROM

Sladek, N.E. “ Antibiotic.”  World Book Encyclopedia.  1999. Pp. 334-335
 

ACKNOWLEDGEMENTS

I would like to thank the following people. Without their help, my project would not have been possible.

  • My mom for transporting me to Memorial Hospital. 
  • My dad for looking over my report with me and suggesting changes.
  • Microbiologist Marie Clark for letting me come to the Hospital and use supplies.
  • All of the volunteers that let me use them for subjects of my experiment.
  • Mrs. Helms for making suggestions regarding my board and for helping me cut things for my board.
  • Other sixth grade students for giving me tips for my project and helping me cut things for my board.
  • Mr. Newkirk for correcting my report and pushing me to do my best.

 
 



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