Name: a method to test the efficacy of handwashing for the removal of emerging infectious pathogens
Uploaded: 2017-06-07T14:00:00.000+00:00
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Description: Watch this Scientific Journal Video about A Method to Test the Efficacy of Handwashing for the Removal of Emerging Infectious Pathogens at JoVE.com

This work was supported by the United States Agency for International Development, Office of Foreign Disaster Assistance (AID-OFDA-A-15-00026). Marlene Wolfe was supported by the National Science Foundation (grant 0966093).

Ethics Statement: The study described here (on Phi6 and E. coli as surrogates for Ebola) was approved by the Institutional Review Board at Tufts Medical Center and Tufts University Health Sciences Campus (#12018); Harvard University ceded review to the Tufts Institutional Review Board.
NOTE: Prior to beginning this protocol, two steps must be completed. First, a Biosafety Level 1 (BSL-1) surrogate or non-infectious version of the pathogen to be studied that is safe to use on human subjects must be identified and selected30. A BSL-1 surrogate or non-infectious pathogen is necessary for this protocol, as the organism will be used to inoculate the bare hands of human volunteers. Second, approval from the local Institutional Review Board to conduct research with human subjects must be obtained before recruiting volunteers or beginning the experiment. Many aspects of this protocol can be adjusted to meet the specific needs of the research questions of interest.
1. Recruit Eligible Human Subjects
<ol>
	<li>Recruit volunteers by posting paper flyers on public notice boards and sending emails to groups with members who may be interested in participating. These announcements should include the study purpose, contact information, and eligibility criteria.</li>
	<li>Meet with the volunteers to evaluate eligibility. Confirm that the volunteers are healthy, between the ages of 18 and 65, and not currently pregnant or taking antibiotics and that they have no skin damage/disorders, known allergies to handwashing agents, or history of mental health issues related to hygiene.</li>
	<li>Have eligible volunteers read consent forms. Answer any questions they pose and have the volunteer and investigator sign two copies of the form. Retain one form and provide one to the volunteer.</li>
	<li>Administer a baseline survey, including questions on demographic information, personal history of skin conditions, and information on recent handwashing behavior. Examine hands for signs of dermatitis, skin injuries, or baseline skin abnormalities31.</li>
	<li>Schedule the volunteers for two testing sessions for each organism of interest (one for testing with soil load and one for testing without). Instruct the volunteers to avoid antimicrobial products for a seven-day washout period prior to testing to avoid confounding from personal product use.
	<ol>
		<li>Provide volunteers with antimicrobial products (shampoo, conditioner, and soap) to use in place of their usual products. Provide heavy-duty vinyl gloves and instruct the subjects to wear them when using products such as house cleaning products.</li>
	</ol>
	</li>
</ol>
2. Prepare Handwashing Solutions Commonly Used in Emergency Response (Soap, ABHS, 0.05% HTH, NaDCC, and NaOCl Solutions)
NOTE: Chlorine solutions can be prepared up to 12 h in advance of the experiment but will degrade if stored &#62;12 h.
<ol>
	<li>Choose and purchase a soap relevant to the context for which testing is being performed. 
	NOTE: In most cases, for infectious disease emergencies in the developing world, this will be a bar of soap.</li>
	<li>Choose and purchase an ABHS solution relevant to the context for which testing is being performed. 
	NOTE: The chosen ABHS should have an ethyl alcohol context greater than or equal to 70% to ensure efficacy.</li>
	<li>Prepare a 0.05% calcium hypochlorite (Ca(ClO)2) solution by adding granular Ca(ClO)2 powder to ultrapure water. Determine the amount of solution needed based on the number of subjects to be tested.
	<ol>
		<li>Using the following equation, determine the amount of powder needed to prepare the desired amount of solution in a given volume of water using a given percent of available chlorine: 
		<img alt="Equation" src="/files/ftp_upload/55604/55604eq1.jpg" /> 
		NOTE: Ca(ClO)2 powder typically has 60-80% available chlorine.</li>
	</ol>
	</li>
	<li>Prepare a 0.05% sodium dichloroisocyanurate (NaDCC) solution by adding a granular NaDCC powder to ultrapure water.
	<ol>
		<li>Using the following equation, determine the amount of powder needed to prepare the desired amount of solution in a given volume of water using a given percent of available chlorine: 
		<img alt="Equation" src="/files/ftp_upload/55604/55604eq2.jpg" /> 
		NOTE: NaDCC powder typically has about 50% available chlorine.</li>
	</ol>
	</li>
	<li>Prepare stabilized 0.05% NaOCl solution by adding stock sodium hypochlorite solution to ultrapure water.
	<ol>
		<li>Confirm the concentration of the NaOCl stock solution (likely to be 5-8%) using a titration test method according to the manufacturer&#39;s instructions (e.g., iodometric titration; see the Materials List for the suggested kit).</li>
		<li>Using the results of the test method, calculate the amount of solution to add to water using the following equation: 
		<img alt="Equation" src="/files/ftp_upload/55604/55604eq3.jpg" /></li>
	</ol>
	</li>
	<li>Prepare stabilized 0.05% NaOCl solution by adding sodium hypochlorite solution produced using an electrochlorinator, ultrapure water, and laboratory-grade sodium chloride (NaCl) to ultrapure water.
	<ol>
		<li>Prepare a 1% chlorine solution with ultrapure water and NaCl, using an electrochlorinator according to the manufacturer&#39;s instructions.</li>
		<li>Use a titration test method (e.g., iodometric titration) to confirm the concentration of the NaOCl stock solution32.</li>
		<li>Using the results of the test, calculate the amount of solution to add to water using the following equation: 
		<img alt="Equation" src="/files/ftp_upload/55604/55604eq3.jpg" /></li>
	</ol>
	</li>
	<li>Confirm the concentration of each of the chlorine handwashing solutions using a titration method (e.g., iodometric titration) and adjust the solutions by adding water or chlorine source powder/solution until they are within a 10% error of the target concentration (0.045-0.055%).</li>
</ol>
3. Prepare Organisms and Soil Load and Combine to Produce the Inoculate
NOTE: In the following sub-sections, E. coli and Phi6 are used as sample bacterial and viral organisms for the methods description.
<ol>
	<li>Prepare the organism to be used for testing at a concentration greater than 10 x 108 CFU/mL for bacteria and greater than 10 x 107 PFU/mL for viruses.
	<ol>
		<li>To prepare E. coli, streak a nonpathogenic strain of E. coli onto Luria-Bertani (LB) agar plates and incubate at 37 &#176;C for 24 h to obtain single colonies. Store at 4 &#176;C. 
		NOTE: This can be done several days before experimentation.
		<ol>
			<li>One day before the start of the experiment, pick a single colony from the plate and inoculate 10 mL of LB broth using a sterile loop. Incubate overnight at 37 &#176;C with shaking.</li>
			<li>On the morning of the experiment, start a fresh culture by adding 1 mL of the overnight culture to 20 mL of fresh LB broth. Incubate for approximately 2.5 h to achieve a cell density greater than 108 CFU/mL.</li>
			<li>Use a spectrophotometer to estimate the concentration of the culture. 
			NOTE: Use a previously established conversion factor from a standards curve for the E. coli strain used, ensuring a concentration greater than 108 CFU/mL33. If the cell density is not high enough, return the culture to the incubator and test again until ready.</li>
		</ol>
		</li>
		<li>Confirm the concentration using membrane filtration34. 
		NOTE: Perform serial dilutions of the culture in phosphate-buffered saline (PBS) so that the solution filtered will produce a countable number of colonies on the plate (the exact number will depend on the medium used).
		<ol>
			<li>Set up a flame and a filtration manifold with sterile filtration funnels and a vacuum connection. Sterilize forceps by flaming them with ethanol. Use them to place a 0.45-&#181;m filter on the filtration manifold, with the grid facing up. Wet the filter with a small amount of sterile PBS.</li>
			<li>Place the funnel on the base and add the sample solution to be processed by pipetting or pouring directly onto the filter. Engage the vacuum until the entire sample has passed through the membrane. Rinse the sides of the funnel with sterile PBS and engage the vacuum again. 
			NOTE: Samples should be at least 100 &#181;L and up to 100 mL. If a sample is less than 10 mL, add approximately 20 mL of PBS to the filtration funnel prior to filtering to ensure the uniform filtration of the sample.</li>
			<li>Remove the funnel, flame-sterilize the forceps, and lift the filter from the base. Place the filter gently on the LB agar in a Petri dish, with the grid facing up, ensuring that the filter lies flush against the surface. Invert the plates and incubate for 24 h at 37 &#176;C.</li>
			<li>After 24 h, remove the plates from the incubator and count the E. coli colonies. Use this data and the known dilution factor and volume of the solution to calculate the concentration of the filtered solution in CFU/mL.</li>
		</ol>
		</li>
		<li>Propagate Phi6 in Pseudomonas syringae host using the double agar overlay method35.
		<ol>
			<li>Add 100 &#181;L of Phi6 stock suspension and 100 &#181;L of P. syringae overnight culture directly to 6 mL of Nutrient Broth Yeast (NBY) soft agar (0.3%). Pour it onto plates with NBY hard agar (1.5%) and incubate overnight at 26 &#176;C. Prepare enough plates to produce enough inoculum for the experiment, estimating a yield of approximately 4 mL of viral suspension per plate.</li>
			<li>The next day, add 5 mL of PBS on top of the soft agar layer. Leave it at room temperature for 4 h, retrieve it with a pipette, and filter it using a 0.45-&#181;m filter. Store at 4 &#176;C. 
			NOTE: This solution will serve as the viral inoculate.</li>
		</ol>
		</li>
		<li>Use a plaque assay to confirm that the concentration is greater than 107 PFU/mL35. Perform serial dilutions of the viral suspension in PBS so that 100 &#181;L produces a countable number of plaques on the plate.
		<ol>
			<li>Pipette 100 &#181;L of an appropriate diluted sample and 100 &#181;L of overnight host culture directly into a tube containing 6 mL of NBY soft agar. Pour soft agar over NBY hard agar and incubate at 26 &#176;C for 24 h.</li>
			<li>The next day, remove the plates from the incubators and count the number of plaques per plate. Use this data and the known dilution factor and volume of the solution to calculate the concentration of the filtered solution in PFU/mL.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Prepare the tripartite soil load, intended to mimic human serum.
	<ol>
		<li>Combine 7.80 mg/mL bovine serum albumin, 10.92 mg/mL tryptone, and 2.52 mg/mL bovine mucin to produce the required volume of soil load. After mixing the soil load, filter it through a 0.22-&#181;m filter to sterilize. Store it at 4 &#176;C until use. Do not heat sterilize, as the proteins will denature.</li>
	</ol>
	</li>
	<li>Prepare a 0.9% NaCl solution for mixing the inoculate for conditions without soil load.</li>
	<li>Immediately prior to testing, prepare an inoculum composed of 68% bacterial or viral suspension and 32% soil load. For example, use 1.02 mL of bacterial or viral suspension from steps 3.1.1.2 or 3.1.3.2 and 0.48 mL of either soil load (step 3.2.1) or 0.9% NaCl solution (step 3.3). Swirl or vortex gently to mix. 
	NOTE: 1.5 mL of this inoculum will be used for each volunteer under each condition, so ensure that the total volume of the inoculum prepared is sufficient for the intended number of tests.</li>
</ol>
4. Preparing Volunteers for the Experiment
NOTE: Determine the organism and soil load condition to be tested on that day. The same volunteers may be used for testing multiple conditions, but each volunteer should only be subjected to one round of testing within a 48 h period.
<ol>
	<li>Before beginning testing, confirm that the volunteers remain eligible by verbally verifying that they adhered to the 7 day antimicrobial washout period and by visually confirming that they have not developed any breaks or abnormalities on their skin.</li>
	<li>Using a random number generator, assign each volunteer to use either their right or left hand for sampling on this day of testing. Assign an order in which the handwashing conditions will be performed. 
	NOTE: For example, ABHS may be assigned #3 and will be performed third.</li>
	<li>Perform a &#34;cleansing wash&#34; once at the start of testing to strip the skin of dirt and oils so that each subsequent test is conducted under equivalent conditions.
	<ol>
		<li>To do a cleansing wash, run through each step of the experiment (section 5, below), using a blank inoculate (LB broth or PBS only) and taking a sample without handwashing.</li>
	</ol>
	</li>
</ol>
5. Experimental Procedure
<ol>
	<li>To test the pH of the skin of each volunteer (to control for variation), place a flat-tipped skin pH probe on the palmar surface skin and the web space between the pointer and middle fingers. Ensure that the electrode is flat against the skin. Record the pH reading.</li>
	<li>Spike the hands.
	<ol>
		<li>Have the volunteers cup both hands together. Spike the hands with 1.5 mL of the inoculate by carefully pipetting 750 &#181;L slowly into each palm.</li>
		<li>Have the volunteers gently rub their hands together until all surfaces of the hand are coated with the inoculate while subjecting the hands to as little friction as possible.</li>
		<li>Have the volunteers hold their hands still and away from their body for an additional 30 s to allow the inoculate to dry. The inoculate may not dry completely.</li>
	</ol>
	</li>
	<li>Wash the hands.
	<ol>
		<li>For all following wash steps, capture the rinse water from the hands in a large sample collection bag. Add 4.5 mL of a 12% sodium thiosulfate solution to the bag to neutralize the chlorine on contact and process within 2 h. 
		NOTE: Sodium thiosulfate should be added to all samples (even those without chlorine) to control for any impact that it may have on the organism.</li>
		<li>After inoculation (section 5.2), wash the hands with the next method in the designated order.
		<ol>
			<li>For Control A, do not perform a handwashing step and move directly to step 5.5.</li>
			<li>For Control B, wash the hands with only ultrapure water at room temperature (approximately 21 &#176;C) through a funnel with a known flow rate. 
			NOTE: Here, a flow rate of 1.5 L/m and 500 mL of water were used.</li>
			<li>For handwashing with soap, wet the hands with 10 mL of ultrapure water. Have the volunteers lather their hands with soap and then rub their hands together for an additional 20 s. Rinse their hands by pouring 500 mL of ultrapure water at room temperature through a funnel at a flow rate of 1.5 L/m.</li>
			<li>For all chlorine solutions (e.g., ABHS, HTH, NaDCC, and NaOCl), pour 200 mL of chlorine solution through a funnel at a flow rate of 1.5 L/m and have the volunteer rub their hands thoroughly.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Hand rinse using a modified glove juice procedure.
	<ol>
		<li>After handwashing, immediately place each volunteer&#39;s hand (i.e., the hand (right or left) selected for testing in step 4.2) into a sample bag containing 75 mL of eluent (e.g., PBS) up to the wrist. Hold the top of the bag tightly around the wrist. 
		NOTE: Use an eluent for sampling that contains sufficient sodium thiosulfate to neutralize any chlorine used for handwashing. PBS is a commonly used eluent that is appropriate for many organisms.</li>
		<li>Have the volunteers gently rub their hand in the solution for 30 s, taking care to reach in between the fingers and underneath the fingernails. Massage the hand from outside the bag gently for 30 s to ensure that the entire hand is rinsed thoroughly in the eluent, all the way up to the wrist.</li>
		<li>Seal the bag and process it according to the appropriate assay, described in section 6, within 2 h.</li>
	</ol>
	</li>
	<li>Decontamination.
	<ol>
		<li>Before repeating the process with each handwashing method, have the volunteers wash their hands thoroughly in a sink with soap and warm water. Spray the volunteers&#39; hands with 70% ethanol until they are coated on both sides. Allow them to dry.</li>
		<li>Repeat all steps in section 5 for each handwashing condition, only using the hand randomly selected in step 4.2 (Figure 1).</li>
	</ol>
	</li>
</ol>
6. Quantification
<ol>
	<li>Perform assays appropriate for the organism of choice (e.g., membrane filtration for bacteria or plaque assay for viruses, described above in sections 3.1.2 and 3.1.4, respectively).</li>
	<li>After counting the plates, record the estimated CFU/mL or PFU/mL for each test for the analyses (sections 3.1.2 and 3.1.4).</li>
</ol>
7. Analysis
<ol>
	<li>Using the results from step 6.2, calculate the log reduction value of organisms on the hands, for each organism and soil load status and for each subject and handwashing method.
	<ol>
		<li>For handwashing efficacy, compare the concentration of bacteria/virus in each handwashing sample to control A (no handwashing). For rinse water persistence, compare each rinse water sample to control B (washing with water only). Use the following standard formula: 
		Log Reduction (handwashing) = <img alt="Equation" src="/files/ftp_upload/55604/55604eq4.jpg" /> <img alt="Equation" src="/files/ftp_upload/55604/55604eq5.jpg" /> 
		Log Reduction (rinse water) = <img alt="Equation" src="/files/ftp_upload/55604/55604eq4.jpg" /><img alt="Equation" src="/files/ftp_upload/55604/55604eq6.jpg" /> 
		NOTE: Log reduction can also be expressed as log10(without handwashing) - log10(with handwashing)</li>
	</ol>
	</li>
	<li>Use a one-way repeated measures analysis of variance (ANOVA) to assess the significant differences in the calculated log reduction values between handwashing methods and a post-hoc Tukey&#39;s HSD test for significant models to pairwise assess significant differences (p &#60;0.05)36.
	<ol>
		<li>Prior to running the ANOVA, assess each dataset for sphericity (e.g., using Bartlett&#39;s test). Apply a correction (e.g., the Greenhouse-Geisser correction) when the test indicates that sphericity was violated37.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Kampf, G., Kramer, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiologic+Background+of+Hand+Hygiene+and+Evaluation+of+the+Most+Important+Agents+for+Scrubs+and+Rubs.">Epidemiologic Background of Hand Hygiene and Evaluation of the Most Important Agents for Scrubs and Rubs.</a> Clin Microbiol Rev. 17 (4), 863-893 (2004).</li><li>Miller, T., Patrick, D., Ormrod, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hand+decontamination:+influence+of+common+variables+on+hand-washing+efficiency.">Hand decontamination: influence of common variables on hand-washing efficiency.</a> Healthc Infect. 16 (1), 18 (2013).</li><li>Jensen, D. A., Danyluk, M. D., Harris, L. J., Schaffner, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+the+effect+of+hand+wash+duration,+soap+use,+ground+beef+debris,+and+drying+methods+on+the+removal+of+Enterobacter+aerogenes+on+hands.">Quantifying the effect of hand wash duration, soap use, ground beef debris, and drying methods on the removal of Enterobacter aerogenes on hands.</a> J Food Prot. 78 (4), 685-690 (2015).</li><li>Girou, E., Loyeau, S., Legrand, P., Oppein, F., Brun-Buisson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+handrubbing+with+alcohol+based+solution+versus+standard+handwashing+with+antiseptic+soap:+randomised+clinical+trial.">Efficacy of handrubbing with alcohol based solution versus standard handwashing with antiseptic soap: randomised clinical trial.</a> BMJ. 325 (7360), 362 (2002).</li><li>Kac, G., Podglajen, I., Gueneret, M., Vaupr&#233;, S., Bissery, A., Meyer, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbiological+evaluation+of+two+hand+hygiene+procedures+achieved+by+healthcare+workers+during+routine+patient+care:+a+randomized+study.">Microbiological evaluation of two hand hygiene procedures achieved by healthcare workers during routine patient care: a randomized study.</a> J Hosp Infect. 60 (1), 32-39 (2005).</li><li>Lages, S. L. S., Ramakrishnan, M. A., Goyal, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-vivo+efficacy+of+hand+sanitisers+against+feline+calicivirus:+a+surrogate+for+norovirus.">In-vivo efficacy of hand sanitisers against feline calicivirus: a surrogate for norovirus.</a> J Hosp Infect. 68 (2), 159-163 (2008).</li><li>Holton, R. H., Huber, M. A., Terezhalmy, G. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+efficacy+of+soap+and+water+hand+washing+versus+an+alcohol-based+hand+cleanser.">Antimicrobial efficacy of soap and water hand washing versus an alcohol-based hand cleanser.</a> Tex Dent J. 126 (12), 1175-1180 (2009).</li><li>Salmon, S., Truong, A. T., Nguyen, V. H., Pittet, D., McLaws, M. -. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Health+care+workers'+hand+contamination+levels+and+antibacterial+efficacy+of+different+hand+hygiene+methods+used+in+a+Vietnamese+hospital.">Health care workers' hand contamination levels and antibacterial efficacy of different hand hygiene methods used in a Vietnamese hospital.</a> Am J Infect Control. 42 (2), 178-181 (2014).</li><li>Steinmann, J., Nehrkorn, R., Meyer, A., Becker, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+in-vivo+protocols+for+testing+virucidal+efficacy+of+handwashing+and+hand+disinfection.">Two in-vivo protocols for testing virucidal efficacy of handwashing and hand disinfection.</a> Int J Hyg Environ Health. 196 (5), 425-436 (1995).</li><li>Weber, D. J., Sickbert-Bennett, E., Gergen, M. F., Rutala, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+selected+hand+hygiene+agents+used+to+remove+Bacillus+atrophaeus+(a+surrogate+of+Bacillus+anthracis)+from+contaminated+hands.">Efficacy of selected hand hygiene agents used to remove Bacillus atrophaeus (a surrogate of Bacillus anthracis) from contaminated hands.</a> JAMA. 289 (10), 1274-1277 (2003).</li><li>Grayson, M. L., Melvani, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+Soap+and+Water+and+Alcohol-Based+Hand-Rub+Preparations+against+Live+H1N1+Influenza+Virus+on+the+Hands+of+Human+Volunteers.">Efficacy of Soap and Water and Alcohol-Based Hand-Rub Preparations against Live H1N1 Influenza Virus on the Hands of Human Volunteers.</a> Clin Infect Dis. 48 (3), 285-291 (2009).</li><li>Oughton, M. T., Loo, V. G., Dendukuri, N., Fenn, S., Libman, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hand+hygiene+with+soap+and+water+is+superior+to+alcohol+rub+and+antiseptic+wipes+for+removal+of+Clostridium+difficile.">Hand hygiene with soap and water is superior to alcohol rub and antiseptic wipes for removal of Clostridium difficile.</a> Infect Control Hosp Epidemiol. 30 (10), 939-944 (2009).</li><li>Liu, P., Yuen, Y., Hsiao, H. -. M., Jaykus, L. -. A., Moe, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effectiveness+of+liquid+soap+and+hand+sanitizer+against+Norwalk+virus+on+contaminated+hands.">Effectiveness of liquid soap and hand sanitizer against Norwalk virus on contaminated hands.</a> Appl Environ Micro. 76 (2), 394-399 (2010).</li><li>Savolainen-Kopra, C., Korpela, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+treatment+with+ethanol+hand+rub+is+ineffective+against+human+rhinovirus--hand+washing+with+soap+and+water+removes+the+virus+efficiently.">Single treatment with ethanol hand rub is ineffective against human rhinovirus--hand washing with soap and water removes the virus efficiently.</a> J Med Virol. 84 (3), 543-547 (2012).</li><li>Tuladhar, E., Hazeleger, W. C., Koopmans, M., Zwietering, M. H., Duizer, E., Beumer, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reducing+viral+contamination+from+finger+pads:+handwashing+is+more+effective+than+alcohol-based+hand+disinfectants.">Reducing viral contamination from finger pads: handwashing is more effective than alcohol-based hand disinfectants.</a> J Hosp Infect. 90 (3), 226-234 (2015).</li><li>Steinmann, J., Paulmann, D., Becker, B., Bischoff, B., Steinmann, E., Steinmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+virucidal+activity+of+alcohol-based+hand+sanitizers+versus+antimicrobial+hand+soaps+in+vitro+and+in+vivo.">Comparison of virucidal activity of alcohol-based hand sanitizers versus antimicrobial hand soaps in vitro and in vivo.</a> J Hosp Infect. 82 (4), 277-280 (2012).</li><li>de Aceituno, A. F., Bartz, F. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ability+of+Hand+Hygiene+Interventions+Using+Alcohol-Based+Hand+Sanitizers+and+Soap+To+Reduce+Microbial+Load+on+Farmworker+Hands+Soiled+during+Harvest.">Ability of Hand Hygiene Interventions Using Alcohol-Based Hand Sanitizers and Soap To Reduce Microbial Load on Farmworker Hands Soiled during Harvest.</a> J Food Protect. 78 (11), 2024-2032 (2015).</li><li>Boyce, J. M., Pittet, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guideline+for+Hand+Hygiene+in+Health-Care+Settings+Recommendations+of+the+Healthcare+Infection+Control+Practices+Advisory+Committee+and+the+HICPAC/SHEA/APIC/IDSA+Hand+Hygiene+Task+Force.">Guideline for Hand Hygiene in Health-Care Settings Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force.</a> Infect Control Hosp Epidemiol. 23 (12 Suppl), S3-S40 (2002).</li><li>. UNDP Medical Waste Experts Assessment and Recommendations Regarding Management of Ebola-Contaminated Waste Available from: <a target="_blank" href="https://noharm-global.org/sites/default/files/documents-files/3127/Report%20to%20WHO%20WASH%20and%20Geneva%20on%20Ebola%20final.pdf">https://noharm-global.org/sites/default/files/documents-files/3127/Report%20to%20WHO%20WASH%20and%20Geneva%20on%20Ebola%20final.pdf</a> (2015)</li><li>Hopman, J., Kubilay, Z., Allen, T., Edrees, H., Pittet, D., Allegranzi, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+chlorine+solutions+used+for+hand+hygiene+and+gloves+disinfection+in+Ebola+settings:+a+systematic+review.">Efficacy of chlorine solutions used for hand hygiene and gloves disinfection in Ebola settings: a systematic review.</a> Antimicrob Resist Infect Control. 4 (1), 1 (2015).</li><li>Lowbury, E. J. L., Lilly, H. A., Bull, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disinfection+of+hands:+removal+of+transient+organisms.">Disinfection of hands: removal of transient organisms.</a> BMJ. 2 (5403), 230-233 (1964).</li><li>Edmonds, S. L., Zapka, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effectiveness+of+Hand+Hygiene+for+Removal+of+Clostridium+difficile+Spores+from+Hands.">Effectiveness of Hand Hygiene for Removal of Clostridium difficile Spores from Hands.</a> Infect Control Hosp Epidemiol. 34 (3), 302-305 (2013).</li><li>Rotter, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=150+years+of+hand+disinfection-Semmelweis'+heritage.">150 years of hand disinfection-Semmelweis' heritage.</a> Hyg Med. (22), 332-339 (1997).</li><li>Hitomi, S., Baba, S., Yano, H., Morisawa, Y., Kimura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+effects+of+electrolytic+products+of+sodium+chloride--comparative+evaluation+with+sodium+hypochlorite+solution+and+efficacy+in+handwashing.">Antimicrobial effects of electrolytic products of sodium chloride--comparative evaluation with sodium hypochlorite solution and efficacy in handwashing.</a> Kansensh&#333;gaku Zasshi. 72 (11), 1176-1181 (1998).</li><li>. Standard E1174-13. Standard Test Method for Evaluation of the Effectiveness of Health Care Personnel Handwash Formulations Available from: <a target="_blank" href="https://www.astm.org/">https://www.astm.org/</a> (2013)</li><li>Casanova, L. M., Weaver, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+eluents+for+the+recovery+of+an+enveloped+virus+from+hands+by+whole-hand+sampling.">Evaluation of eluents for the recovery of an enveloped virus from hands by whole-hand sampling.</a> J Appl Microbiol. 118 (5), 1210-1216 (2015).</li><li>Sinclair, R. G., Rose, J. B., Hashsham, S. A., Gerba, C. P., Haas, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Criteria+for+Selection+of+Surrogates+Used+To+Study+the+Fate+and+Control+of+Pathogens+in+the+Environment.">Criteria for Selection of Surrogates Used To Study the Fate and Control of Pathogens in the Environment.</a> Appl Environ Microbiol. 78 (6), 1969-1977 (2012).</li><li>Held, E., Skoet, R., Johansen, J. D., Agner, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+hand+eczema+severity+index+(HECSI):+A+scoring+system+for+clinical+assessment+of+hand+eczema.+A+study+of+inter-+and+intraobserver+reliability.">The hand eczema severity index (HECSI): A scoring system for clinical assessment of hand eczema. A study of inter- and intraobserver reliability.</a> Br J Dermatol. 152 (2), 302-307 (2005).</li><li>. Method 1604: Total Coliforms and Escherichia coli in Water by Membrane Filtration Using a Simultaneous Detection Technique (MI Medium) Available from: <a target="_blank" href="https://www.epa.gov/sites/production/files/2015-08/documents/method_1604_2002.pdf">https://www.epa.gov/sites/production/files/2015-08/documents/method_1604_2002.pdf</a> (2002)</li><li>Adams, M. H., Anderson, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Bacteriophages. , (1959).</li><li>Kao, L. S., Green, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+Variance:+Is+There+a+Difference+in+Means+and+What+Does+It+Mean?.">Analysis of Variance: Is There a Difference in Means and What Does It Mean?.</a> The Journal of surgical research. 144 (1), 158-170 (2008).</li><li>Schutz, R. W., Gessaroli, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Analysis+of+Repeated+Measures+Designs+Involving+Multiple+Dependent+Variables.">The Analysis of Repeated Measures Designs Involving Multiple Dependent Variables.</a> Research Quarterly for Exercise and Sport. 58 (2), 132-149 (1987).</li><li>Woolwine, J. D., Gerberding, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+testing+method+on+apparent+activities+of+antiviral+disinfectants+and+antiseptics.">Effect of testing method on apparent activities of antiviral disinfectants and antiseptics.</a> Antimicrob Agents Chemother. 39 (4), 921-923 (1995).</li></ol>

The authors declare that they have no competing financial interests.

The method described here provides an approach for testing handwashing efficacy in a controlled laboratory setting. This method highlights the use of human volunteers and surrogate, non-infectious organisms. Using the method, it was possible to demonstrate differences in: 1) the efficacy of handwashing methods and 2) organism persistence in rinse water. The purpose of presenting this protocol is to provide a general framework that can be adapted to test a wide range of surrogate organisms and handwashing methods relevant to infectious disease.
During the use of the method, two key data quality recommendations were noted as important. First, the inoculate must be applied both as similarly as possible across the rounds of testing and in a manner, that minimizes loss. This is to ensure that sufficient inoculate is applied to the hands to allow for statistically significant results. Second, be sure to complete the "cleansing wash" step, in which the protocol is performed without handwashing prior to testing, as previous work has shown that there are likely to be significant differences between a first wash and subsequent washes, but not between subsequent washes performed after a cleansing round29. Additionally, this step clears residual hand contamination, which would interfere with results. 
The main limitation of this protocol is that it can be uncomfortable for volunteers. During each round of testing, which lasted about 2 h, volunteers' hands became cold. Some volunteers reported mild pain from their hands being constantly wet. Additionally, after a few rounds of testing, volunteers' hands became supersaturated, no longer fully drying between rounds. Although the randomization of the order of handwashing methods for each volunteer accounted for supersaturation, it is possible that the supersaturation could act as a confounding or modifying factor in this type of testing. To address this limitation, it is recommended that volunteers are appraised of this risk during consent disclosures and are reminded of their right to drop out of the study at any time. Volunteers should not undergo testing for more than 2 h per day to allow time for the hands to return to a baseline state and to minimize discomfort. A second limitation is the need to use a surrogate organism or non-infectious variant of a pathogenic organism to protect the health of volunteers. This might cause concern about the generalizability of results. However, for some pathogenic organisms (such as the Ebola virus), this limitation cannot be ethically overcome. Care must be taken during surrogate organism selection. Lastly, this is a laboratory study on efficacy. Results may only translate to effective disease prevention in real-word contexts where handwashing methods are made accessible to those in need and are used properly and consistently.
This protocol draws on previous work on handwashing efficacy but attempts to streamline methods and emphasizes the use of human hands (rather than surrogate surfaces) for testing. Additionally, rinse water is a transmission risk that had previously not been assessed. Existing studies on handwashing efficacy vary in methodology, leading to non-comparable data. We hope that standardized protocols for conducting handwashing method comparisons will encourage comparable and replicable results. Previous work has demonstrated that in vitro testing on surrogate surfaces such as pig skin, where, for example, the actual Ebola virus could be used, produced results that do not match those found after testing on human hands38. Therefore, a method using human hands and surrogate or non-infectious organisms is currently the best available approach to estimate handwashing efficacy and rinse water persistence for infectious microorganisms.
Handwashing is critical to prevent disease transmission. However, there is a lack of evidence on the comparative efficacy of handwashing methods that are commonly recommended. This protocol can be used to generate evidence about handwashing efficacy and rinse water persistence. This is especially important for infectious diseases with the potential to cause large outbreaks, such as the Ebola virus. We hope that other researchers will find this protocol useful to generate much-needed additional evidence on handwashing method efficacy and rinse water persistence that will assist in developing recommendations to reduce the transmission of infectious diseases.

Handwashing is widely recommended to prevent the spread of disease, particularly those transmitted by the fecal-oral or airborne route, including diarrheal and respiratory diseases1. Surprisingly, there is little comparable evidence on the efficacy of handwashing methods, such as handwashing with soap and water (HWWS) and with alcohol-based hand sanitizer (ABHS), on the removal of organisms from the hands. Initial research has found that the mechanical action of handwashing, as opposed to the handwashing method, may account for most organism removal2,3. Additionally, there is little comparative evidence on which handwashing method is most efficacious. In an informal literature review, 14 studies that compared the efficacy of soap and hand sanitizer on the removal of organisms were identified. Of these studies, five found ABHS to be more efficacious4,5,6,7,8, seven found HWWS to be more efficacious9,10,11,12,13,14,15, and two found no significant difference between the methods16,17. These findings are inconsistent and do not address the ongoing risk of disease from the persistence of organisms in the rinse water after handwashing. Overall, the evidence on the comparative efficacy of handwashing methods for the removal of infectious disease-causing pathogens is limited.
This limited evidence has led to uncertainty about which methods are most appropriate in outbreak settings. For example, during the Ebola Virus Disease (EVD) outbreak in West Africa from 2013 to 2016, several large international responders provided contradictory recommendations for HWWS, ABHS, or 0.05% chlorine solutions. M&#233;decins Sans Fronti&#232;res (MSF) recommends the use of 0.05% chlorine solution for handwashing, while the World Health Organization (WHO) recommends HWWS or ABHS (if the hands are not visibly soiled). The WHO goes so far as to state that chlorine should not be used unless no other options are available, because it is less effective than other methods due to the chlorine demand exerted by the skin18,19,20,21,22. Additionally, the chlorine solutions are commonly produced from four different chlorine compounds, including high-test hypochlorite (HTH), locally-generated and stabilized sodium hypochlorite (NaOCl), and sodium dichloroisocyanurate (NaDCC). A systematic review commissioned by the WHO in response to the EVD outbreak in West Africa recently found only four studies investigating the comparative efficacy of handwashing with chlorine23. These studies also produced conflicting results, and none of these studies used the recommended chlorine concentration of 0.05% for handwashing or investigated microorganisms similar to the Ebola virus10,24,25,26,27. Thus, the recommendations were not found to be evidence-based, and it was unclear which recommendations were most efficacious.
Additional research is needed to compare handwashing approaches to prevent the spread of infectious pathogens, as handwashing interventions are an important tool to prevent epidemic disease transmission. These handwashing recommendations must be based on evidence. Thus, a method for testing handwashing efficacy and rinse water persistence, performed with surrogates or non-infectious pathogens, was developed2,28,29. Sample results, using Phi6 as a surrogate for the Ebola virus and using Escherichia coli as a common indicator organism, are presented here. In this protocol, handwashing efficacy and rinse water persistence tests are presented.

<table><tbody><tr><td>Soap bar</td><td>Dove</td><td>White Beauty Bar soap</td><td></td></tr><tr><td>Alcohol-based hand sanitizer</td><td>Purell</td><td>Advanced Instant Hand Sanitizer with 70% Ethyl Alcohol</td><td></td></tr><tr><td>HTH Powder</td><td>Acros Organics</td><td>300340010</td><td></td></tr><tr><td>NaDCC Powder</td><td>Medentech</td><td>Klorsept granules</td><td></td></tr><tr><td>NaOCl Solution</td><td>Acros Organics</td><td>419550010</td><td></td></tr><tr><td>Electrochlorinator</td><td>AquaChlor</td><td></td><td></td></tr><tr><td>Iodometric titrator</td><td>Hach</td><td>1690001</td><td></td></tr><tr><td>Bovine serum albumin</td><td>MP Biomedicals</td><td>NC0117242</td><td></td></tr><tr><td>Tryptone</td><td>Fisher</td><td>BP1421-100</td><td></td></tr><tr><td>Bovine Mucin</td><td>EMD Milipore</td><td>49-964-3500MG</td><td></td></tr><tr><td>0.22 &amp;micro;m Filter</td><td>EMD Milipore</td><td>GVWP04700</td><td></td></tr><tr><td>NaCl</td><td>Fisher</td><td>BP358-1</td><td></td></tr><tr><td>Skin pH probe</td><td>Hanna Instruments</td><td>H199181</td><td></td></tr><tr><td>Large Whirlpak Sample Bag</td><td>Nasco</td><td>B01447WA</td><td></td></tr><tr><td>Small Whirlpak Sample Bag</td><td>Nasco</td><td>B01323WA</td><td></td></tr><tr><td>Funnel bottle</td><td>Thermo Scientific</td><td>3120850001</td><td>You may drill an appropriately sized hole in the lid of a bottle to form a funnel that will dispense water at the appropriate flow rate</td></tr><tr><td>Ethanol</td><td>ThermoScientific</td><td>615090010</td><td>Mix with water to produce 70% ethanol</td></tr><tr><td>Spray bottle</td><td>Qorpak</td><td>PLC06934</td><td></td></tr><tr><td>&lt;em&gt;E. coli&lt;/em&gt;</td><td>ATCC</td><td>25922</td><td></td></tr><tr><td>LB Broth</td><td>Fisher BioReagents</td><td>BP1426-2</td><td></td></tr><tr><td>LB Agar</td><td>Fisher BioReagents</td><td>BP1425-500</td><td></td></tr><tr><td>Sterile loop</td><td>Globe Scientific</td><td>22-170-204</td><td></td></tr><tr><td>Phi6</td><td>HER</td><td>102</td><td></td></tr><tr><td>Nutrient broth</td><td>BD Difco</td><td>BD 247110</td><td></td></tr><tr><td>GeneQuant 100 Spectrophotometer</td><td>General Electric</td><td>28-9182-04</td><td></td></tr><tr><td>Sodium thiosulfate</td><td>Fisher Chemical</td><td>S445-3</td><td></td></tr><tr><td>Membrane filter (47 mm, 0.45 &amp;micro;m)</td><td>EMD Millipore</td><td>HAWP04700</td><td></td></tr><tr><td>m-ColiBlue24 broth media</td><td>EMD Millipore</td><td>M00PMCB24</td><td></td></tr><tr><td>Petri dish with pad (47 mm)</td><td>Fisherbrand</td><td>09-720-500</td><td></td></tr><tr><td>Vacuum Manifold</td><td>Thermo Scientific/Nalgene</td><td>09-752-5</td><td></td></tr><tr><td>Filter funnels</td><td>Thermo Scientific/Nalgene</td><td>09-747</td><td></td></tr><tr><td>Pseudomonas syringae</td><td>HER</td><td>1102</td><td></td></tr><tr><td>Phosphate Buffered Saline</td><td>Thermo Scientific</td><td>10010031</td><td>Solution may also be mixed from source compounds according to any basic recipe</td></tr></tbody></table>

a method to test the efficacy of handwashing for the removal of emerging infectious pathogens

Handwashing is widely recommended to prevent infectious disease transmission. However, little comparable evidence exists on the efficacy of handwashing methods in general. Additionally, little evidence exists comparing handwashing methods to determine which are most efficacious at removing infectious pathogens. Research is needed to provide evidence for the different approaches to handwashing that may be employed during infectious disease outbreaks. Here, a laboratory method to assess the efficacy of handwashing methods at removing microorganisms from hands and their persistence in rinse water is described. Volunteers' hands are first spiked with the test organism and then washed with each handwashing method of interest. Generally, surrogate microorganisms are used to protect human subjects from disease. The number of organisms remaining on volunteers' hands after washing is tested using a modified "glove juice" method: the hands are placed in gloves with an eluent and are scrubbed to suspend the microorganisms and make them available for analysis by membrane filtration (bacteria) or plaque assay (viruses/bacteriophages). Rinse water produced from the handwashing is directly collected for analysis. Handwashing efficacy is quantified by comparing the log reduction value between samples taken after handwashing to samples with no handwashing. Rinse water persistence is quantified by comparing rinse water samples from various handwashing methods to samples collected after handwashing with just water. While this method is limited by the need to use surrogate organisms to preserve the safety of human volunteers, it captures aspects of handwashing that are difficult to replicate in an in vitro study and fills research gaps on handwashing efficacy and the persistence of infectious organisms in rinse water.

Here, the protocol (Figure 1) was completed with 18 volunteers, who were each tested using both E. coli and Phi6. Significant differences were found between handwashing results with E. coli both with and without soil load and Phi6 with soil load (Figure 2 and Figure 3). For E. coli without soil load, handwashing with HTH, NaDCC, and stabilized NaOCl all resulted in significantly greater log reductions than handwashing with water only (F(6,102) = 2.72, p = 0.034). With soil load, HTH resulted in a significantly greater log reduction of E. coli than water only, HWWS, and ABHS (F(6,102) = 3.94, p &#60;0.001). There was no significant difference between methods for Phi6 without soil load (F(6,66) = 2.04, p = 0.073). However, for Phi6 with soil load (F(6,102) = 7.01, p &#60;0.001), water alone resulted in a greater log reduction than ABHS or stabilized NaOCl, and HWWS in a greater log reduction than ABHS, stabilized NaOCl, and generated NaOCl. HTH also had a greater log reduction than ABHS and stabilized NaOCl, and NaDCC resulted in a greater log reduction than stabilized NaOCl and ABHS. While HTH performed most consistently well across conditions, we would caution against over-interpretation of significant results, as many confidence intervals were large, ranging from less than 0.5 log to more than 1.5 log reduction in many cases.
In rinse water, chlorine resulted in a significantly greater log reduction of E. coli persisting in the rinse water than HWWS (without soil load, F(4,68) = 331.7, p &#60;0.001; with soil load, F(4,68) = 162.44, p &#60;0.001) (Figure 4). This same pattern was found in Phi6 without soil load ((F(4,43) = 8.95, P &#60;0.001), with all chlorine solutions resulting in a significantly greater reduction of Phi6 in rinse water than HWWS. There were no significant differences in persistence in rinse water with Phi6 and soil load ((F(4,67) = 3.35, p = 0.071) (Figure 5).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55604/55604fig1.jpg" /> 
Figure 1: Experiment overview. The five steps undertaken for each round of handwashing include: 1) pH testing, 2) inoculating the hands, 3) handwashing, 4) rinsing the hands, and 5) decontaminating the hands for each of the eight conditions tested. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55604/55604fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/55604/55604fig2.jpg" /> 
Figure 2: E. coli handwashing results. Compared to no handwashing, the handwashing methods tested resulted in an average log reduction in E. coli of 1.94-3.01 without soil load and 2.18-3.34 with soil load. Handwashing with water demonstrated the least reduction in E. coli in both conditions (1.94 and 2.18 log). Handwashing with NaDCC resulted in the greatest reduction without soil load (3.01), and HTH resulted in the greatest reduction with soil load (3.34). In the charts, the line represents the percent reduction in organisms, and the error bars represent the standard error of log reduction. Ctrl B, control B; HWWS, handwashing with soap; ABHS, alcohol-based hand sanitizer; HTH, high-test hypochlorite; NaDCC, sodium dichloroisocyanurate; st NaOCl, stabilized sodium hypochlorite; gen NaOCl, generated sodium hypochlorite. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55604/55604fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/55604/55604fig3.jpg" /> 
Figure 3: Phi6 handwashing results. Compared to no handwashing, the handwashing methods tested resulted in an average log reduction in Phi6 of 2.44-3.06 without soil load and 2.71-3.69 with soil load. Handwashing with soap demonstrated the least reduction in Phi6 without soil load (2.44), and handwashing with stabilized NaOCl resulted in the smallest reduction with soil load (2.71). Handwashing with generated NaOCl resulted in the greatest reduction without soil load (3.06), and handwashing with soap resulted in the greatest reduction with soil load (3.69). In the charts, the line represents the percent reduction in organisms, and the error bars represent the standard error of log reduction. Ctrl B, control B; HWWS, handwashing with soap; ABHS, alcohol-based hand sanitizer; HTH, high-test hypochlorite; NaDCC, sodium dichloroisocyanurate; st NaOCl, stabilized sodium hypochlorite; gen NaOCl, generated sodium hypochlorite. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55604/55604fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/55604/55604fig4.jpg" /> 
Figure 4: E. coli hand rinse results. Compared to hand washing with water only, the average log reduction of E. coli remaining in the rinse water was 0.28-4.77 without soil load and 0.21-4.49 with soil load. Both with and without soil load, the smallest reduction was found in handwashing with soap (0.28 and 0.21). The greatest reductions were observed with stabilized and generated NaOCl without soil load (both 4.77) and with HTH and generated NaOCl with soil load. In the charts, the line represents the percent reduction in organisms, and the error bars represent the standard error of log reduction. HWWS, handwashing with soap; ABHS, alcohol-based hand sanitizer; HTH, high-test hypochlorite; NaDCC, sodium dichloroisocyanurate; st NaOCl, stabilized sodium hypochlorite; gen NaOCl, generated sodium hypochlorite. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55604/55604fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/55604/55604fig5.jpg" /> 
Figure 5: Phi6 hand rinse results. Compared to hand washing with water only, the average log reduction of Phi6 remaining in the rinse water was 1.26-2.02 without soil load and 1.30-2.20 with soil load. With soil load, the smallest reduction was found in handwashing with soap (1.26). Without soil load, HTH resulted in the smallest reduction (2.02). The greatest reductions were observed both with and without soil load with NaDCC (2.02 and 2.20). In the charts, the line represents the percent reduction in organisms, and the error bars represent the standard error of log reduction. HWWS, handwashing with soap; ABHS, alcohol-based hand sanitizer; HTH, high-test hypochlorite; NaDCC, sodium dichloroisocyanurate; st NaOCl, stabilized sodium hypochlorite; gen NaOCl, generated sodium hypochlorite. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55604/55604fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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A Method to Test the Efficacy of Handwashing for the Removal of Emerging Infectious Pathogens

Handwashing is widely recommended to prevent infectious disease transmission. However, there is little evidence on which handwashing methods are most efficacious at removing infectious disease pathogens. We developed a method to assess the efficacy of handwashing methods at removing microorganisms.

Handwashing is widely recommended to prevent infectious disease transmission. However, little comparable evidence exists on the efficacy of handwashing ...

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JoVE Journal

Immunology and Infection

19.0K Views.  Tufts University.  Handwashing wordt algemeen aanbevolen om infectieziekte overdracht te voorkomen. Er is echter weinig bewijs aan welke handwasmethoden het meest effectief zijn bij het verwijderen van infectieuze ziektepatogenen. Wij ontwikkelden een methode om de werkzaamheid van handwasmethoden bij het verwijderen van micro-organismen te beoordelen. 

Video: A Method to Test the Efficacy of Handwashing for the Removal of Emerging Infectious Pathogens

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. I. Collection of Virus Samples

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. The standardized sampling component of the method concentrates viruses that may be present in water by passage of a minimum specified volume of water through an electropositive cartridge filter. The minimum specified volumes for surface and finished/ground water are 300 L and 1,500 L, respectively. A major method limitation is the tendency for the filters to clog before meeting the sample volume requirement. Studies using two different, but equivalent, cartridge filter options showed that filter clogging was a problem with 10% of the samples with one of the filter types compared to 6% with the other filter type. Clogging tends to increase with turbidity, but cannot be predicted based on turbidity measurements only. From a cost standpoint one of the filter options is preferable over the other, but the water quality and experience with the water system to be sampled should be taken into consideration in making filter selections.

EPA Method 1615 uses an electropositive filter to concentrate enteroviruses and noroviruses in environmental and drinking waters. This manuscript describes the procedure for collecting samples for Method 1615 analyses.

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. ...

Environment

Determining Viral Disinfection Efficacy of Hot Water Laundering

This protocol provides an example of a laboratory process for conducting laundering studies that generate data on viral disinfection. While the protocol was developed for research during the coronavirus disease 2019 (COVID-19) pandemic, it is intended to be a framework, adaptable to other virus disinfection studies; it demonstrates the steps for preparing the test virus, inoculating the test material, assessing visual and integrity changes to the washed items due to the laundering process, and quantifying the reduction in viral load. Additionally, the protocol outlines the necessary quality control samples for ensuring the experiments are not biased by contamination and measurements/observations that should be recorded to track the material integrity of the personal protective equipment (PPE) items after multiple laundering cycles. The representative results presented with the protocol use the Phi6 bacteriophage inoculated onto cotton scrub, denim, and cotton face-covering materials and indicate that the hot water laundering and drying process achieved over a 3-log (99.9%) reduction in viral load for all samples (a 3-log reduction is the disinfectant performance metric in U.S. Environmental Protection Agency's Product Performance Test Guideline 810.2200). The reduction in viral load was uniform across different locations on the PPE items. The results of this viral disinfection efficacy testing protocol should help the scientific community explore the effectiveness of home laundering for other types of test viruses and laundering procedures.

In response to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, a laboratory protocol was developed to test the viral disinfection efficacy of hot water laundering of cloth face coverings, cotton scrubs, and denim pants. The Phi6 virus (bacteriophage) was used as the organism to test disinfection efficacy.

This protocol provides an example of a laboratory process for conducting laundering studies that generate data on viral disinfection. While the protocol ...

Engineering

Swab Sampling Method for the Detection of Human Norovirus on Surfaces

Human noroviruses are a leading cause of epidemic and sporadic gastroenteritis worldwide. Because most infections are either spread directly via the person-to-person route or indirectly through environmental surfaces or food, contaminated fomites and inanimate surfaces are important vehicles for the spread of the virus during norovirus outbreaks.
We developed and evaluated a protocol using macrofoam swabs for the detection and typing of human noroviruses from hard surfaces. Compared with fiber-tipped swabs or antistatic wipes, macrofoam swabs allow virus recovery (range 1.2-33.6%) from toilet seat surfaces of up to 700 cm2. The protocol includes steps for the extraction of the virus from the swabs and further concentration of the viral RNA using spin columns. In total, 127 (58.5%) of 217 swab samples that had been collected from surfaces in cruise ships and long-term care facilities where norovirus gastroenteritis had been reported tested positive for GII norovirus by RT-qPCR. Of these 29 (22.8%) could be successfully genotyped. In conclusion, detection of norovirus on environmental surfaces using the protocol we developed may assist in determining the level of environmental contamination during outbreaks as well as detection of virus when clinical samples are not available; it may also facilitate monitoring of effectiveness of remediation strategies.

A macrofoam based sampling methodology was developed and evaluated for the detection and quantification of norovirus on environmental hard surfaces.

Human noroviruses are a leading cause of epidemic and sporadic gastroenteritis worldwide. Because most infections are either spread directly via the ...

Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method

As rates of multidrug-resistant (MDR) pathogens continue to rise, outpacing the development of new antimicrobials, novel approaches to treatment of MDR bacteria are increasingly becoming a necessity. One such approach is combination therapy, in which two or more antibiotics are used together to treat an infection against which one or both of the drugs may be ineffective alone. When two drugs, in combination, exert a greater than additive effect, they are considered synergistic. In vitro investigation of synergistic activity is an important first step in evaluating the possible efficacy of drug combinations. Two main in vitro synergy testing methods have been developed: the checkerboard array and the time-kill study. In this paper, we present an automated checkerboard array method that makes use of inkjet printing technology to increase the efficiency and accuracy of this technique, as well as a standard manual time-kill synergy method. The automated checkerboard array can serve as a high-throughput screening assay, while the manual time-kill study provides additional, complementary data on synergistic activity and killing.
The checkerboard array is a modification of standard minimum inhibitory concentration (MIC) testing, in which bacteria are incubated with antibiotics at different concentration combinations and evaluated for growth inhibition after overnight incubation. Manual performance of the checkerboard array requires a laborious and error-prone series of calculations and dilutions. In the automated method presented here, the calculation and dispensing of required antibiotic stock solution volumes are automated through the use of inkjet printer technology. In the time-kill synergy assay, bacteria are incubated with the antibiotics of interest, both together and individually, and sampled at intervals over the course of 24 h for quantitative culture. The results can determine whether a combination is synergistic and whether it is bactericidal, and provide data on inhibition and killing of bacteria over time.

Antimicrobial synergy testing is used to evaluate the effect of two or more antibiotics used in combination and is typically performed by one of two methods: the checkerboard array or the time-kill assay. Here, we present an automated, inkjet printer-assisted checkerboard array synergy technique and a classic time-kill synergy study.

As rates of multidrug-resistant (MDR) pathogens continue to rise, outpacing the development of new antimicrobials, novel approaches to treatment of MDR ...

VirWaTest, A Point-of-Use Method for the Detection of Viruses in Water Samples

Viruses excreted by humans and animals may contaminate water sources and pose a risk to human health when this water is used for drinking, food irrigation, washing, etc. The classical fecal bacteria indicator does not always check for the presence of viral pathogens so the detection of viral pathogens and viral indicators is relevant in order to adopt measures of risk mitigation, especially in humanitarian scenarios and in areas where water-borne viral outbreaks are frequent.
At present, several commercial tests allowing the quantification of fecal indicator bacteria (FIB) are available for testing at the point of use. However, such commercial tests are not available for the detection of viruses. The detection of viruses in environmental water samples requires concentrating several liters into smaller volumes. Moreover, once concentrated, the detection of viruses relies on methods such as nucleic acid extraction and molecular detection (e.g., polymerase chain reaction [PCR]-based assays) of the viral genomes.
The method described here allows the concentration of viruses from 10 L water samples, as well as the extraction of viral nucleic acids at the point of use, with simple and portable equipment. This allows the testing of water samples at the point of use for several viruses and is useful in humanitarian scenarios, as well as at any context where an equipped laboratory is not available. Alternatively, the method allows concentrating viruses present in water samples and the shipping of the concentrate to a laboratory at room temperature for further analysis.

Here we present VirWaTest, which is a simple, affordable and portable method for the concentration and detection of viruses from water samples at the point of use.

Viruses excreted by humans and animals may contaminate water sources and pose a risk to human health when this water is used for drinking, food ...

Prion Safety Laboratory Swipe Test

Transmission of iatrogenic prion disease has occurred from contaminated neurosurgical tools, transplant materials, and occupational exposure to prion-contaminated laboratory tools. Prions cause disease by the templated misfolding of the normal cellular form of the prion protein, PrPC, into the misfolded and pathogenic form PrPSc and are invariably fatal. Reducing iatrogenic and occupational prion transmission is challenging. First, prions can bind to and persist on surfaces for long periods of time. Second, prions are highly resistant to inactivation. Given this, surfaces can retain infectivity for long periods of time following ineffective decontamination. Not only can this pose a potential occupational risk for prion laboratory workers, but it could potentially cross-contaminate laboratory experiments utilizing sensitive prion amplification techniques. The protocol described here for a prion safety laboratory swipe test includes steps for the identification and documentation of high-traffic laboratory areas, recommended swabbing controls to ensure the validity of results, steps to identify proper responses to positive surface swabbing sites, representative results from prion swipe testing, as well as potential artifactual results. Overall, the prion safety laboratory swipe test can be implemented as part of a broader prion safety program to assess decontamination of surfaces, monitor common spaces for prion contamination, and implement the documentation of prion decontamination status.

A method to assess commonly used areas in laboratory settings for prion contamination and effective decontamination is lacking. The protocol described here provides key fundamentals for implementing a laboratory prion safety swipe test that can easily be modified to meet the individual needs of specific laboratories.

Transmission of iatrogenic prion disease has occurred from contaminated neurosurgical tools, transplant materials, and occupational exposure to ...

Swabbing the Urban Environment - A Pipeline for Sampling and Detection of SARS-CoV-2 From Environmental Reservoirs

To control community transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the 2020 global pandemic, most countries implemented strategies based on direct human testing, face covering, and surface disinfection. Under the assumption that the main route of transmission includes aerosols and respiratory droplets, efforts to detect SARS-CoV-2 in fomites have focused on locations suspected of high prevalence (e.g., hospital wards, cruise ships, and mass transportation systems). To investigate the presence of SARS-CoV-2 on surfaces in the urban environment that are rarely cleaned and&#160;seldomly disinfected, 350 citizens were enlisted from the greater San Diego County. In total, these citizen scientists collected 4,080 samples. An online platform was developed to monitor sampling kit delivery and pickup, as well as to collect sample data. The sampling kits were mostly built from supplies available in pandemic-stressed stores. Samples were processed using reagents that were easy to access despite the recurrent supply shortage. The methods used were highly sensitive and resistant to inhibitors that are commonly present in environmental samples. The proposed experimental design and processing methods were successful at engaging numerous citizen scientists who effectively gathered samples from diverse surface areas. The workflow and methods described here are relevant to survey the urban environment for other viruses, which are of public health concern and pose a threat for&#160;future pandemics.

A citizen science project was designed to recruit San Diego residents to collect environmental samples for SARS-CoV-2. A multilingual web-based platform was created for data submission using a user-friendly mobile device interface. A laboratory information management system facilitated the collection of thousands of geographically diverse samples with real-time outcome tracking.

To control community transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the 2020 global pandemic, most countries ...

Biology

Antimicrobial Efficacy of Nano-Herbal-Coated Fabrics

An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and burns. These cotton-based protective coats provide ideal conditions for microbial growth and attachment sites due to their porous nature, moisture-holding capacity, and retention of warmth from the user&#39;s body. Several studies have demonstrated the survival of pathogenic bacteria on hospital garments and lab coats, acting as vectors of microbial transmission.
A common approach to fix these problems is the application of antimicrobial agents in textile finishing, but concerns have been raised due to the toxicity and environmental effects of many synthetic chemicals. The ongoing pandemic has also opened a window for the investigation of effective antimicrobials and eco-friendly and toxic-free formulations. This study uses two natural bioactive compounds, carvacrol and thymol, encapsulated in chitosan nanoparticles, which guarantee effective protection against four human pathogens with up to a 4-log reduction (99.99%). These pathogens are frequently detected in lab coats used in biohazard laboratories.
The treated fabrics also resisted up to 10 wash cycles with 90% microbial reduction, which is sufficient for the intended use. We made modifications to the existing standard fabric tests to better represent the typical scenarios of lab coat usage. These refinements allow for a more accurate evaluation of the effectiveness of antimicrobial lab coats and for the simulation of the fate of any accidental microbial spills that must be neutralized within a short time. Further studies are recommended to investigate the accumulation of pathogens over time on antimicrobial lab coats compared to regular protective coats.

Author Spotlight: An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils  

Antimicrobial lab coats prevent the cross-contamination of pathogen accumulation and accidental bio-spills. Here, we describe the protocol for developing a skin-friendly antimicrobial fabric using nano-herbal encapsulation and modified standard tests to precisely evaluate the efficacy and suitability for typical usage of the lab coat.

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and ...

Hand hygiene

Asepsis is the practice of preventing or breaking the chain of infection. The nurse employs aseptic techniques to prevent the spread of microorganisms and reduce the risk of diseases. Hand hygiene is the cornerstone of aseptic techniques and is classified into medical and surgical asepsis. Medical asepsis includes hand hygiene and the use of gloves. Surgical asepsis, or the sterile technique, refers to practices that render and keep objects and areas free of microorganisms.
Hand washing consists of a fast, vigorous rubbing motion across all parts of the hands, with lathered surfaces, followed by 15 seconds of washing under water. Handwashing works by mechanically removing microorganisms from the hands and rinsing them with water. Microorganisms are not killed by handwashing. There are three techniques of hand washing.
Hand washing 
By performing hand hygiene at the right moments and using appropriate techniques, hands become clean and safe as infectious organisms are not transmitted to yourself or others. Using handwashing products that contain an antimicrobial or antibacterial ingredient is recommended in any setting where the risk for infection is high, such as:
<ul>
	<li>&#8226; When hands are visibly soiled with blood and body fluids</li>
	<li>&#8226;&#160;Before eating and after toileting</li>
	<li>&#8226;&#160;When exposed to spore-forming microorganisms.</li>
</ul>
Antiseptic hand wash
An antiseptic hand rub is used to decrease the number of microorganisms present on hand surfaces by applying an antiseptic hand rub. Ethanol-based hand antiseptics containing 70% to 90% alcohol appear to be the most effective against common pathogens found on the hands.
All healthcare workers must practice proper hand hygiene at all times, including:
<ul>
	<li>&#8226;&#160;Just before touching a patient</li>
	<li>&#8226;&#160;Before performing an aseptic task or working with invasive devices</li>
	<li>&#8226;&#160;Before switching from a soiled to a clean body site on a patient</li>
	<li>&#8226;&#160;After contacting a patient or their immediate surroundings</li>
	<li>&#8226;&#160;Following exposure to blood, bodily fluids, or contaminated surfaces (with or without glove use)</li>
	<li>&#8226;&#160;Immediately following glove removal</li>
</ul>
Antiseptic hand rub or surgical hand antisepsis 
Surgical hand antisepsis is an antiseptic hand wash or hand-rub technique that is an integral part of the preparation for surgery by surgical personnel. Its purpose is to eliminate transient microorganisms and reduce resident hand flora. The most currently used antiseptics are chlorhexidine (CHG) and povidone-iodine (PVI). These agents are applied with a sponge and brush. This technique involves coating the elbow to the fingers and can take up to three minutes, depending on hospital protocol.

Asepsis is the practice of preventing or breaking the chain of infection. The nurse employs aseptic techniques to prevent the spread of microorganisms and ...

Education

JoVE Core

Nursing

Unit 1

Infection Prevention and Control

KEY TERMS AND CONCEPTS

Handwashing II: Pre-procedure and Initial Procedure Steps

The pre-procedure steps of handwashing include removing jewelry and rolling up sleeves. However, many organizations allow staff to wear wedding rings.
The hand washing procedure itself includes the following steps. First, cover cuts, if any, on hands with a waterproof dressing. Cuts and abrasions can become contaminated with bacteria hindering the ability to clean the area thoroughly. In addition, repeated hand washing can worsen an injury.&#160; The nails must be short and clean, without nail paint or artificial nails. Long and false nails and imperfections in nail polish harbor dirt and microorganisms that are not entirely removed by hand washing.
Next, turn on the taps and direct the water flow away from the drain. Run the water at a flow rate that prevents splashing. Drain openings are often contaminated with microorganisms that could be transferred to the environment or the user if splashing occurs.
Wet hands, and use enough soap to cover all surfaces. Soap applied directly onto dry hands may damage the skin.

The pre-procedure steps of handwashing include removing jewelry and rolling up sleeves. However, many organizations allow staff to wear wedding rings.
The ...

A Method to Test the Efficacy of Handwashing for the Removal of Emerging Infectious Pathogens

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