Do More Expensive Hand Sanitizers Inhibit Bacterial Proliferation Better Than Less Expensive Ones? By: Henry Microbe Grade 7
Question / Problem To determine which hand sanitizer will inhibit the proliferation of Escherichia coli (E. coli )for the lowest cost.
Background Research • A. Bacteria • 1. Kingdom a. Eubacteria 2. Prokaryotic Cells 3. Methods of Classifying Bacteria a. Shape 1. Coccus - Round 2. Bacillus - Rod 3. Spirillum - Spiral b. Gram Staining 1. Gram + = purple 2. Gram - = red c. Clustering / Grouping 1. Diplo= two bacteria 2. Strepto= chain of bacteria 3. Staphylo= cluster of bacteria • E. coli • A. Bacillus bacteria • B. Gram - • C. Normally found in the intestines of animals • D. Diseases Caused by E. coli • 1. Urinary Tract Infection • 2. Diarrhea • 3. Nausea • 4. Possible Death
Hypothesis As the price of the hand sanitizer increases its ability to inhibit bacterial proliferation will increase.
Variables Manipulated / Independent Responding / Dependent The hand sanitizers being tested Swan, Germ-x Aloe, Purell Adv., Germ-x Foaming, Germ-x The ability of the hand sanitizers to inhibit bacterial proliferation Constants Nuisance • 1- Pure slant of E. coli • 21- Sterile Tryptic Soy Agar (TSA) plates • 84 - Sterile blank discs • Incubated at 37° C • Incubator used • Method of determining the average zone of inhibition • Minor fluctuations in temperature and humidity in the incubator • Age & viability of the E. coli • Irregular zones of inhibition
Materials Used • Pen • Paper • Incubator • 21 Sterile Tryptic Soy Agar (TSA) Petri Dishes • 84 Sterile Blank Discs • Sterile Saline Water (H20) • Hydrogen Peroxide (H202) • Sterile Latex Gloves • Sterile Tweezers • Sterile Beakers • Black Sharpie Marker • .22µm Millex Millipore Filter • Goggles • Sterile Nutrient Broth • Hand Sanitizers Tested: • Swan Brand $0.37/100mL • Germ-x Aloe $0.55/100mL • PurellAdvance $1.13/100mL • Germ-x Foam $1.19/100mL • Germ-x$1.33/100mL
Experimental Procedure Step 2 Divide 21 Tryptic Soy agar (TSA) plates into 4 equal size quadrants Step 4 Inoculate 50mL of sterile nutrient broth solution with E. coli & incubate for 72 hours at 37 º C Step 1 Obtain needed materials Step 3 Sterilize work area with Hydrogen Peroxide Step 6 Dip a sterile disc into a sterile saline watersolution (- Control) Step 5 Inoculate 21 Tryptic Soy agar plates from Step 2 with 1 mL of the nutrient broth/E. coli solution prepared in step 4 Step 8 Repeat steps 6-7 using 3 more test discs Step 7 Place the sterile disc from Step 6 in the center of one of the quadrants on one of the TSA plates Step 12 Determine and record the average zone of inhibition for each of the sterile discs dipped in the solutions being tested Step 9 Repeat steps 6-8 using 2 more TSA plates prepared in Step 2 Step 10 Repeat Steps 6 – 9 for peroxide (+ Control) and each of the hand sanitizers being tested Step 11 Incubate all Petri dishes for 72 hrs. at 37 º C
Determining the Average Zone of Inhibition for Hydrogen Peroxide (+ Control) Sterile Disc Dipped in H₂O₂ Optional Slide Photo: A
Two Sample Independent T-Test Sterile Saline H2O (- Control) Significance Level = 0.05 Claim: µ1 = µ2 Confidence Level = 95% Optional Slide
Two Sample Independent T-Test Hydrogen Peroxide (+ Control) Significance Level = 0.05 Claim: µ1 = µ2 Confidence Level = 95% Optional Slide
Conclusion Based on the data I collected from my experiment I concluded that the data partially supported my hypothesis. Hypothesis As the price of the hand sanitizer increases its ability to inhibit bacterial proliferation will increase. Actual Results Hand Sanitizer Cost/100 mL Average Zone of Tested Inhibition (mm) Swan Brand $0.37 5.58 Germ-x Aloe $0.55 4.46 Purell Advance $1.13 6.88 Germ-x Foam $1.19 3.46 Germ-x $1.33 5.50 H2O2 (+ Control) $0.35 9.58 Saline (- Control) $0.22 0.00
Conclusion Based on the Two Sample Independent T-Test that I performed on the data that I collected from my experiment I concluded that the data partially supported my hypothesis. Hypothesis As the price of the hand sanitizer increases its ability to inhibit bacterial proliferation will increase. Results Significance Level = 0.05 Confidence Level = 95% Saline Vs Sanitizer H2O2 Vs Samitizer Hand Sanitizer Cost/(P Value) (Hypothesis) (P Value) (Hypothesis) Tested 100mL Swan Brand $0.37 0.0023 Accepted 0.0510 Rejected Germ-x Aloe $0.55 0.0450 Accepted0.0400 Accepted Purell Advance $1.13 0.0031 Accepted 0.0148 Accepted Germ-x Foam $1.19 0.0420 Accepted 0.0550 Rejected Germ-x $1.33 0.0380 Accepted 0.0410 Accepted H2O2 (+Control) $0.35 Saline (-Control) $0.22 Conclusion Based on Statistical Analysis Optional Slide
Future Improvements / Changes • Test more discs for each of the hand sanitizers being tested. (≥ 30 discs) • Perform more trials (3 – 10 trials) • Use a different protocol for determining the ability of hand sanitizers to inhibit bacterial proliferation. • Purchase a greater number of hand sanitizers
Future Experiments / Extensions • Design an experiment inorder to determine the effect of hand sanitizers on a variety of different types of bacteria. • Perform an experiment in order to determine the ability of natural herbs and spices to inhibit bacterial proliferation. • Design and perform an experiment in order to determine whether bacteria will develop a resistance to various antibacterial chemicals. • Perform an experiment in order to test the ability of different types of anti bacterial hand soaps to inhibit bacterial proliferation. • Design and perform a similar experiment with hand soap
Real Life Applications • The results obtained from my experiment could be used by cafeterias, restaurants, and hospitals to purchase the least expensive but most effective hand sanitizer. • The results obtained from my experiment could assist my family to purchase the least expensive and most effective hand sanitizer for home use. • This information could assist retailers in determining the most effective hand sanitizer to purchase for the least cost.
Bibliography of Sources "Clinical Infectious Diseases." Consumer Antibacterial Soaps: Effective or Just Risky?N.p., n.d. Web. 05 Dec. 2013. "On the Structure of Eukaryotic, Prokaryotic, and Viral Chromatin." On the Structure of Eukaryotic, Prokaryotic, and Viral Chromatin. N.p., n.d. Web. 05 Dec. 2013. "Zone of Inhibition." - Definition from Biology-Online.org. N.p., n.d. Web. 04 Feb. 2014. "10-2 The Antibiotic Disk Sensitivity Test." Microbiology Labs. N.p., n.d. Web. 05 Feb. 2014. "Escherichia Coli." Wikipedia. Wikimedia Foundation, 27 Jan. 2014. Web. 05 Feb. 2014. "Wash Your Hands." Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 11 Dec. 2013. Web. 03 Feb. 2014.
Gram Staining Procedure Procedure: A. Slant Cultures 1. Prepare and heat-fix smears. 2. Prepare the smears of S. epidermidis and N. sicca on a second slide. Heat-fix. 3. Stain the slides as follows: a. Flood the crystal violet for one minute. b. Pour off excess dye and wash gently in tap water and drain the slide against a paper towel. c. Expose the smears to Gram's iodine for one minute by washing with iodine, then adding more iodine and leaving it on the smear until the minute is over. d. Wash with tap water and drain carefully. (Do not blot.) e. Wash with 95% alcohol for 30 seconds. f. Wash with tap water at the end of the 30 seconds to stop the decolorization. Drain. g. Counterstain with 0.25% safranin for 30 seconds. h. Wash, drain, blot, and examine under oil. i. Draw the cells showing morphology, grouping, and relative sizes. Color a few of the cells of each bacterial species to show the Gram reaction. j. Save these slides and the ones from parts B & C of this exercise to use at the next lab period. Optional Slide
Active Ingredients Hand Sanitizer Active Ingredient Percentage Swan Brand($0.37/100mL) Ethyl Alcohol 65% Germ-x Aloe($0.55/100mL)Ethyl Alcohol 62% Purell Advance($1.13/100mL) Ethyl Alcohol 70% Germ-x Foaming($1.19/100mL) Benzalkonium Chloride 0.13% Germ-x($1.33/100mL) Ethyl Alcohol 63% Optional Slide
Sterile Saline Water (- Control) Optional Slide Photo: B