Blow Dryer and Paper Towel Microbiological Comparison. Presented by Sean Bailey

Transcription

1 Blow Dryer and Paper Towel Microbiological Comparison Presented by Sean Bailey

2 This Experiment to determine which is a more sanitary method of drying one's hands paper towels, or hot air hand dryers Two experiments were performed One, in which plates with E. coli were subjected to paper towels and hot air dryers

3 Previous Studies Previous studies have found warm air dryers increase the amount of bacteria on fingerpads, while paper towels decrease it after washing hands, drying with warm air dryers increased bacteria by over 200% and paper towels decreased it by over 50% warm air dryers operate at a temperature that is nonlethal to bacteria

4 Warm Air Dryers invented in 1948 by George Clemens air circulated by fans is heated by coil and forced out a nozzle onto wet hands since its invention, has undergone very minor changes addition of an air filter infrared switch in lieu of push button

5 Paper Towels invented in 1919 by the Brown Company, in Massachusetts they are an absorbent textile made of paper loosely woven, so very absorbent no moving parts involved - very low tech evolution perforated sheets on rolls "select-a-size" basic function not changed

6 Escherichia coli (E. coli) Part of the human flora; found in the human colon and digestive tract. Cells are rod shaped and usually about 2 micrometers in length. One of the most studied and widely understood types of bacteria. Reproduces rapidly, often within thirty minutes. Commonly used as a prokaryote cell model. Many strains, most non-pathogenic.

7 Hypotheses Null Hypothesis Neither warm air dryers nor paper towels will have a significant effect on microbiological survivorship. Alternative Hypothesis Both warm air dryers and paper towels will have a significant effect on microbiological survivorship.

8 Materials warm air dryer paper towels E. coli (DH5-alpha) LB media and agar plates (0.5% yeast extract, 1% tryptone, 1% sodium chloride) incubator spreader bars turntable labeling tape Sharpie marker stopwatch click counter cardboard forceps

9 Procedure 1 Control 1. Four LB agar plates were opened for thirty seconds and then closed. Warm Air Dryer 2. Four plates were opened, placed on a large piece of cardboard to hold them level, and placed under the hand dryer at a distance of 15cm. 3. The dryer was activated for ten seconds. After the dryer was turned off, the plates were closed.

10 Procedure 1 (cont'd) 4. This process was repeated three different times, with four plates each for ten, twenty, and thirty seconds. Paper Towel 5. Four circles, of the approximate size of an agar plate, were cut out of generic paper towel. 6. Each circle was placed on a plate with sterile forceps. The bottom of a sterile beaker was used to press the towel onto the plate. The paper towel was removed after ten seconds.

11 Procedure 1 (cont'd) 7. This process was repeated three different times, with four plates each for ten, twenty, and thirty seconds. 8. All plates were incubated overnight at 37 degrees Celsius, the colonies counted, and the data statistically analyzed.

12 Results Control The control had very little microbiological growth. Plate Colonies Control 1 2 Control 2 0 Control 3 3 Control 4 0

13 Results Hand Dryer The hand dryer plates had very little microbiological growth, only slightly more than the control. Plates Colonies (avg) HD 10s 2.25 HD 20s 1.5 HD 30s 5.5

14 Results Paper Towel The paper towel plates also had very little microbiological growth, but more than both the control and the hand dryer plates. Plates Colonies (avg) PT 10s 5.5 PT 20s 7.5 PT 30s 7.75

15 Conclusions very little bacteria is being transferred from either the hand dryer or the paper towel to the recipient. all changes in microbiological growth in the second experiment were purely because of the bacteria-killing ability of the variable

16 Procedure 2 1.Bacteria (E. coli) were grown overnight in sterile LB media. 2.Samples of the overnight cultures were added to fresh media in a sterile sidearm flask. 3.The cultures were placed in an incubator (37 C) until a density of 50 Klett spectrophotometer units was reached for each. This represents a cell density of approximately 10 8 cells/ml. 4.The cultures were diluted in sterile dilution fluid to a concentration of approximately 10 3 cells/ml.

17 Procedure 2 (cont'd) μl of aliquots were added to 32 agar plates and were spread plated. Control 6. 8 plates were separated from the stack and set aside until incubation. Warm Air Dryer 7. Four plates were placed on a piece of cardboard to keep them level and place under a warm air dryer for ten seconds.

18 Procedure 2 (cont'd) 8. This process was repeated, with four plates being subjected to ten, twenty, and thirty seconds of air. Paper Towel 9. Four circles, of the approximate size of an agar plate, were cut out of generic paper towel. 10. Each circle was placed on a plate with sterile forceps. The bottom of a sterile beaker was used to press the towel onto the plate. The paper towel was removed after ten seconds.

19 Procedure 2 (cont'd) 11. This process was repeated three different times, with four plates each for ten, twenty, and thirty seconds. 12. The plates were incubated overnight at 37 degrees Celsius, the resulting colonies were counted, and the data was collected and statistically analyzed.

20 Results Hand Dryer

21 Results Paper Towel

22 Results - Dunnett's Paper Towel T-crit is 3.5 T value Significant? Hand Dryer (10s) YES Hand Dryer (20s) 8.17 YES Hand Dryer (30s) 5.12 YES

23 Conclusions The null hypothesis was rejected for the paper towel imprint technique on infused plates Pressing the paper towel onto the plate significantly reduced the colony survivorship on the agar. The null hypothesis was accepted for the hand dryer exposure.

24 Limitations and Extensions Limitations The warm air dryer and the paper towels were not in the same location, which could affect the dryer results because they were transported in fairly cold temperatures. The plating was not perfectly synchronized. Only three exposure times were utilized. Extensions Test more exposure times. Test in an environment equipped with both a warm air dryer and paper towels. Test jet air dryers in addition to warm air dryers. Test different brands of paper towels.

25 Works Cited Ansari, Shamim A., et. al. Comparison of cloth, paper, and warm air drying in eliminating viruses and bacteria from washed hands. Study. American Journal of Infection Control: Volume 19, Issue 5, Pp , October Web. 10 Jan Gustafson, Daniel R., et. al. Effects of four hand-drying methods for removing bacteria from washed hands: a randomized trial. Study. Mayo Clinic Proc: Issue 75, Pp , Web. 10 Jan Redway, Keith, and Shameem Fawdar. A comparative study of three different hand drying methods: paper towel, warm air dryer, jet air dryer. Study. European Tissue Symposium, Nov Web. 8 Jan < Schwarz, Evelyn. Study of different methods used for drying hands. Study. European Tissue Symposium, May 2004 to Feb Web. 10 Jan < "World Dryer - The Hand Dryer Standard." Automatic Hand Dryer : Commercial Hair Dryers : Restroom Hand Dryer : Hot Air Hand Dryers : World Hand Dryer : World Dryer. World Dryer, n.d. Web. 10 Jan <