Cost of Clean: Comparison of Antibacterial Hand Soaps and Their Effectiveness

This study focused on comparing the ability of the same active ingredient, in separate hand soaps, to kill bacteria through hand washing. The two soap products tested were Dial and SpaSoap, one brand name and one less expensive off brand soap. The effectiveness of the two hand soaps were examined on a universal growth media to clearly compare the results. The samples were collected by using a swab culture to collect the bacteria on the palm of the hands before washing with the antibacterial soap for two minutes. This step was repeated before and after washing the hands, and was done to equal a total of 40 samples. Each soap had the same active ingredient, benzalkonium chloride, with the same concentration of 0.13%. The results displayed that each antibacterial soap had shown to be effective in killing a substantial amount of bacteria after hand washing. This research paper will also go into depth, discussing the pros and cons that mainstreaming the use of antibacterial soap present. However, the main purpose was to establish whether there was a difference in effectiveness due to cost of the product. I hypothesize that if both hand washes contain the same amount of the antibacterial ingredient, benzalkonium chloride, that both hand soaps will be equally effective in killing bacteria.

Introduction

Bacteria can be found anywhere, there is no way we can avoid coming in contact with bacteria on a day to day basis. Throughout all of the hand to hand contact, things we touch after washing our hands, and just overall sanitation around us there is hardly any way to avoid these microscopic organisms. A study published by the Cambridge University Press found that about 28% of their sample population had bacteria of fecal origin on their hands. Many studies have been done on the effectiveness of aseptic techniques within health care workers going from patient to patient, it was found that only about 30% of the time these doctors and nurses are actually washing their hands within the time they are interacting with patients. Hand washing is considered to be the first line of defense in fighting acquired infections, meaning that washing hands should be habitual, and one should want to be using the most efficient product to kill the most bacteria. However, this is a double-sided sword.

Popular products that contain harsh chemicals such as Triclosan, which have been shown to inhibit the growth of gram-positive and gram-negative bacteria, may influence the emergence of new drug resistant bacteria. As stated in “Consumer Antibacterial Soaps: Effective or Just Risky?” “The resistance mechanisms are similar to those producing antibiotic resistance and include mutations at the drug target site, chromosome-mediated drug efflux, and overexpression of the target protein. Acquired bacterial resistant mechanisms may lead to an increase in MICs to antibiotics as well as triclosan.” There are also significant environmental risk to consider as well.

Materials and Method

In order to produce accurate result all experiments conducted require the proper materials and techniques. The experiment was conducted with four different people washing their hands five different times. Two of the subjects used the expensive soap (Dial), and the other two subjects used the cheaper soap (SpaSoap). Resulting in ten pre-washing samples for each soap, and ten post-washing samples for each soap. The subjects swabbed their hands before and after hand washing using cotton swabs or pads. The swabs and pads were then stored in labeled and zipped plastic bags until the samples could be inoculated. During inoculation aseptic technique was applied to prevent contamination, and protect those conducting the experiment. Aseptic technique includes wearing proper protective gear, applying the correct techniques of inoculation, and working close to an open flame in order prevent airborne contamination. The medium we chose to inoculate the samples was trypticase soy agar plates. TSA plates are not selective or differential, therefore a great medium for the observation of bacterial growth. Twenty TSA plates were used, ten for the Dial soap, and ten for the SpaSoap. The plates were then divided into two sections. The side with the pre-washing sample was labeled “dirty”, and the other side containing the post-washing sample was labeled “clean”. Once the plates had been inoculated they were stored at 37°C into an incubator. The incubator is kept at the optimal temperature for bacterial growth (37° C) because bacteria prefer body temperature. A week after inoculation the plates were removed from incubation and observations were made.

Results

Post incubation, microbial growth could be seen on both the TSA plates for the Dial and SpaSoap. From visual examination alone both soaps showed a decrease in microbial colonies on the “clean side” of the plate compared to the “dirty side”. The results of the experiment were quantified using a ranking system. The system ranks from zero to five, a rating of zero indicating there are very little to no bacterial growth, and a rating of five indicates extreme bacterial growth. Once all of the plates were ranked, the rankings for both the soaps were averaged. The difference in bacterial growth from pre-washing to post-washing for the Soft Soap, or cheaper option, was 1.2, whereas the difference in bacterial growth for the Dial, the expensive option, is 0.9. The difference in rankings between the SpaSoap and the Dial is only 0.3. Based on the ranking averages the SpaSoap inhibited bacterial growth better than the Dial soap, although not by much.

Conclusion

In this experiment, researchers tested the effectiveness of Dial antibacterial hand soap compared to the cheaper brand, SpaSoap, to determine which soap would kill more bacteria. The researchers wanted to see if spending.18 cent per ounce for Dial versus 03 cent per ounce for SpaSoap was worth the money. Each soap contained the same antibacterial ingredient of benzalkonium chloride with a similar concentration of 13%, therefore the hypothesis was that the soaps would be equally effective in fighting bacteria. The results of the experiment did not support that hypothesis. SpaSoap left the least amount of bacteria cultures on average when used compare to the Dial soap. Though the results only differed slightly the Spa Soap brand was more effective killing bacterial growth. Considering Dial soap is six times the cost of Spa Soap it can be said that a cheaper hand soap containing the same concentration of a similar antibacterial ingredient is not less effective. Research shows that the cost of clean can be as low as .03 cents per ounce. I recommend the use of SpaSoap as an antibacterial hand soap because it is cheaper by volume and was shown to be more effective than the more expensive Dial hand soap.

Work Cited

• Aiello, Allison E., Elaine L. Larson, and Stuart B. Levy. 'Consumer antibacterial soaps: effective or just risky?.' Clinical Infectious Diseases 45.Supplement_2 (2007): S137-S147.
• Sprunt, Katherine, Winifred Redman, and Grace Leidy. 'Antibacterial effectiveness of routine hand washing.' Pediatrics 52.2 (1973): 264-271.
• Eli N.Perencevich MD, Michael T.Wong MD, Anthony D. Harris MD
• “National and regional assessment of the antibacterial soap market: A step toward determining the impact of prevalent antibacterial soaps.” American Journal of Infection Control. Volume 29, Issue 5, October 2001, Pages 281-283