The Effect of Handwashing with Water or Soap on Bacterial Contamination of Hands

 

hand washing lab report

Bacteria Lab Report. This simple experiment not only demonstrates the importance of hand washing but also highlights the necessity of using aseptic techniques when studying bacteria in a lab. Had the plates been left open during inoculation, bacteria present in the air and other surfaces could have contaminated the culture producing. Biology Hand Wash Lab Introduction: You are aware that you have been taught to wash your hands often, especially before eating and after; well, you know Purpose: In this lab, you are going to assess the value of that hand-washing advice and the methods that bring the . disease? How can thorough hand washing limit the spread of infectious diseases? Description of Content In this activity, students will conduct an experiment on washing their hands. They will learn that “clean” hands may not be so clean after all and the critical importance of washing their hands as a way to prevent the spread of disease.


Effectiveness of Handwashing | Microbiology in Review


Handwashing is thought to be effective for the prevention of transmission of diarrhoea pathogens. However it is not conclusive that handwashing with soap is more effective at reducing contamination with bacteria associated with diarrhoea than using water only.

In this study 20 volunteers contaminated their hands deliberately by touching door handles and railings in public spaces. They were then allocated at random to 1 handwashing with water, 2 handwashing with non-antibacterial soap and 3 no handwashing.

Each volunteer underwent this procedure 24 times, yielding samples overall. Bacteria of potential faecal origin mostly Enterococcus and Enterobacter spp. The effect did not appear to depend on the bacteria species. Handwashing with non-antibacterial soap and water is more effective for the removal of bacteria of potential faecal origin from hands than handwashing with water alone and should therefore be more useful for the prevention of transmission of diarrhoeal diseases.

Diarrhoeal diseases are one of the hand washing lab report causes of child death around the world [ 1 ]. The World Health Organisation WHO recognises the spread of diarrhoeal diseases as a serious global problem [ 2 ] and estimates that each year, there are more than 2. The majority of these deaths are in children under 5 years of age [ 3 ]. It has been suggested hand washing lab report handwashing may substantially reduce the risk of diarrhoeal diseases [ 4 ].

Promotion of improved hand hygiene has been recognised as an important public health measure but it is unclear how much hand hygiene is required to interrupt transmission of diarrhoea pathogens. In particular it has not been conclusively shown whether use of soap is essential to remove pathogens from hands.

Recent hygiene promotion campaigns especially in low income settings have not been unanimous in recommending soap use [ 4 ]. A number of studies have compared different hand hygiene methods in hospital settings [ 5 ]. In contrast, hand washing lab report, few studies have been published on the effect of hand hygiene on bacterial contamination of hands in the community.

Hoque and colleagues found that a wide variety of hand cleansing means in poor settings soap, ash, mud are effective in reducing the contamination with coliform bacteria on hands [ 67 ]. In a small randomised trial the same author reported that soap may be more effective than water in reducing the presence of coliform bacteria on hands [ 6 ]. Luby and colleagues found that a simple microbiological method with three fingers directly imprinting a MacConkey agar for thermotolerant coliforms was unable to distinguish between households who were given soap during a large randomized handwashing trial and control households [ 8 ].

They concluded that the method was unsuitable for the evaluation of handwashing practices. However, hand washing lab report, the lack of difference in bacterial contamination may have been due to lack of compliance with the intervention. We thought that a proof-of-principle trial was needed where participants would be given specific tasks to contaminate their hands in a naturalistic setting and where handwashing was done under supervision. We conducted a randomised controlled trial to determine whether non-antibacterial soap is better at reducing bacteria of potential faecal origin than water only.

This study was carried out between July and August Overall, 20 volunteers were taken to a large, frequently visited British museum, or asked hand washing lab report travel on a bus or the underground. They were asked to deliberately wipe their hands over hand contact surfaces such as handrails, door handles and seats with the aim of contaminating their hands with whatever bacteria were present. Using a pre-determined random sequence, not known to the participants during self-contamination, participants were then asked to wash their hands with soap, to use water only or not to wash at all.

Each volunteer underwent this sequence 24 times, 8 times for each of the three hand hygiene approaches soap, water, no handwash. Participants assigned to handwashing were asked to wash their hands as they would normally do, without instructions on length of time or thoroughness. The volunteers allocated to handwashing were then provided with a paper towel to dry their hands. A wet NaCl-soaked charcoal swab was then wiped across the fingers of the dominant hand of the participant. The swabs were returned to the laboratory within 5 hours of being taken.

In total, samples were collected; after handwashing with plain soap, after handwashing with water alone and with no handwashing. During the experimental phase we measured the amount of time taken to conduct handwashing with and without soap, once for each volunteer. Upon arrival at the laboratory the swabs were immediately cut into a universal tube containing 10 mL of Purple MacConkey broth using aseptic techniques.

All samples were then streaked onto the MacConkey agar No. MacConkey agar No, hand washing lab report. For all other colonies produced on Hand washing lab report agar No. Bile Aesculin agar is a differential medium for the isolation of Enterococcus spp, hand washing lab report. Enterococcus and Group D Streptococcus spp.

Any white colonies on Bile Aesculin agar were presumed to be Staphylococcus spp. Agglutination indicated a positive result for Enterococcus spp. The prevalence of bacterial contamination in the three study arms soap, water, no handwash was compared using logistic regression. Since the same volunteers hand washing lab report underwent testing, within-subject correlation was accounted for by the use of generalised estimating equations GEE with robust standard errors.

If the cell numbers were too low for conducting regression analysis, Fishers exact test was used instead, ignoring clustering the design effect was found to be low, see results. Table 1 shows the different organisms isolated in the three study arms. Enterococcus spp. Figure 1 shows the effect of handwashing with soap or water only on contamination, compared to no handwashing. Overall, hand washing lab report, handwashing with water alone reduced the prevalence of bacteria substantially.

Handwashing with soap was more effective in reducing the prevalence of contamination and specifically of Enterococcus spp. There was a trend that handwashing with soap was also more effective in reducing the prevalence of other species and of multiple isolates, but the statistical support was low Figure 1. Effect of handwashing with water alone or soap and water compared to no handwashing. The design effect due to within-person clustering was low around 1, hand washing lab report.

Note different y-axis scales in top vs. Organisms found after self-contamination of hands, hand washing lab report, and handwashing with either soap, water only, or no handwashing. The effect of repeated measurements in the same individual was low: the design effect the factor by which a sample size needs to be increased to achieve the same statistical power as an unclustered study ranged from 1.

Participants were asked to wash their hands as long and as thorough as they would normally do, hand washing lab report. The length of time required to carry out handwashing was measured once for each method in all volunteers. Participants took on average 12 seconds standard deviation 2. Thus, handwashing with soap took them only slightly longer than handwashing with water alone. It seems unlikely that this small difference can explain the large difference in the removal of bacteria, hand washing lab report.

Soap on its own appears to have an effect hand washing lab report the removal of bacteria of potential faecal origin, independent of the possibility that soap use may cause people to wash their hands longer. Unlike the study by Hoque and colleagues our trial was conducted in an experimental albeit naturalistic setting, where volunteers deliberately contaminated their hands. It also improved control over the conduct of the experiment, but may affect generalisability, as the study primarily aimed at providing a proof of principle.

However, we believe that the superior effect of soap on the removal of bacteria compared to water alone as the principal finding of our study is unlikely to depend on the setting. Not all of the bacteria isolated in our study are known to cause disease in humans. Surprisingly, we found few E. Overall, hand washing lab report, the effect of soap appeared to be independent of the type of bacteria Figure 1hand washing lab report, a view which is supported by the study by Hoque and colleagues who found a similar effect of hand hygiene on unspecified faecal coliform bacteria [ 6 ].

However, the power of our study to detect differences between species was low. We used plain non-antibacterial soap for the experiment.

Future studies could address whether antibacterial soap is more effective in removing pathogens from hands. However, Luby and colleagues conducted a large double-blind randomised trial in Pakistan and found antibacterial soap no more effective in reducing diarrhoea than normal soap [ 11 ].

It is still not clear whether or in what circumstances anti-bacterial soaps offer a health advantage [ 12 ], hand washing lab report. The bacteriological methods used in this study provide no quantification of bacterial load, hand washing lab report, unlike a study by Hoque and colleagues [ 7 ]. Quantifying the effect of different hand washing procedures on bacterial load may be particularly helpful for studies in poor settings with poor sanitation facilities, where the environmental contamination with faecal organisms is much higher [ 13 — 15 ].

We hand washing lab report tested a semi-quantitative finger-print method used previously in Thailand [ 15 ] not unsimilar to the method used by Luby and colleagues [ 8 ] but found that contamination levels were too low to provide consistent results.

Therefore we decided to use a qualitative method. It seems reasonable to assume that handwashing with soap is also more effective in reducing bacterial load compared to water alone. Future studies could address the effect of different hand hygiene procedures on removing gastro-intestinal or respiratory viruses such as influenza A. Hands have been implicated especially in the spread of Norovirus [ 16 ]. Viral studies are more difficult to conduct as viruses may not be as present in the environment as hand washing lab report as are bacteria of faecal origin, but they may be possible for example if patients with laboratory confirmed infection are recruited as volunteers.

Alternatively, healthy volunteers may experimentally contaminate their hands with cultured viruses before undergoing different hand hygiene regimes, as was done in a recent study on influenza A H1N1 [ 17 ]. This study found that handwashing with soap was better at removing influenza A H1N1 than several hand sanitizers. Handwashing with water alone was not tested. The results demonstrate that handwashing with non-antibacterial soap is much more effective in removing bacteria from hands than handwashing with water only.

Although handwashing with water alone reduced the presence of bacteria on hands substantially, the study supports the policy of many current hand hygiene campaigns promoting the use of soap [ 1819 ].

The strong association between hand hygiene method hand washing lab report bacterial contamination of hands found in our study suggests that the prevalence of hand washing lab report indicator bacteria may also be used to monitor changes in hygiene behaviour in the general population, for example following hygiene promotion campaigns. Hygiene behaviour is difficult to measure because people tend to change their behaviour under observation or over-report desired practices [ 1520 ].

We have previously shown that our test kit can be used to study associations between hygiene relevant behaviours and hand contamination [ 9 ], hand washing lab report.

We found that test results positive for bacteria of potential faecal origin were more common in people frequently shaking hands, reporting soil contact or those scoring low on a hygiene score based on self-report [ 9 ]. Its suitability for large scale use in the evaluation of handwashing campaigns in low income settings where handwashing should be most beneficial remains to be investigated.

A sophisticated laboratory infrastructure may not be required to conduct testing. However, modifying the method to allow semi-quantitative or quantitative analysis may be necessary if contamination rates are high [ 15 ]. National Center for Biotechnology InformationU. Published online Jan 6. Author information Article notes Copyright and License information Disclaimer.

This article has been cited by other articles in PMC. Abstract Handwashing is thought to be effective for the prevention of transmission of diarrhoea pathogens.

 

 

hand washing lab report

 

Jan 06,  · Quantifying the effect of different hand washing procedures on bacterial load may be particularly helpful for studies in poor settings with poor sanitation facilities, Hygiene behaviour is difficult to measure because people tend to change their behaviour under observation or over-report desired practices [15,20].Cited by: Background This laboratory exercise illustrates the critical need for proper hand washing techniques as a means of reducing the incidence of healthcare facility acquired infections. The exercise compares the effectiveness of two hand washing techniques: using water only, and using soap and water. The student is exposed to the fact that the hands harbor microorganisms. Handwashing Effectiveness Laboratory Instructions: The final lab report needs to be a complete, typed document. Please use your data and your notes on the hypothesis and controls that you have been working on these past few weeks for the appropriate sections. The report must be typed. Please include all the sections below that are in bold.