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A comparative study of the effectiveness of triclosan containing antibacterial soaps and regular soaps on Gram positive and Gram negative bacteria J. Y. Greenfield, S. A Rand, N. M. Chikwem, D. S. McKnight, T. L. Coleman, J. Toto and J. O Chikwem* Department of Biology, Lincoln University, PA 19352 Abstract The anti bacterial effectiveness of four non-triclosan containing hand soaps was compared with that of six triclosan containing hand soaps. Dilutions of the soaps were used in the preparation of pour plates which were then streaked with cultures of Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium and Bacillus cereus. After incubation at 37oC for 18 hours, none of the four non-triclosan containing soaps inhibited the growth of the gram-negative bacteria, E. coli, S. typhimurium and Ps. aeruginosa. However, the two Gram-positive bacteria, B. cereus and Staph. aureus, were inhibited by some concentrations of soaps. B. cereus was inhibited by all four brands of soap at concentrations of 1.0% and above, while only DG Body inhibited Staph. aureus at 2%. On the other hand, all six triclosan containing hand soaps inhibited the growth of S. typhimurium and E. coli at concentrations of 0.5% and above. None of the hand soaps in this study inhibited the growth of Ps. aeruginosa. We therefore conclude that triclosan containing hand soaps are more effective in inhibiting the growth of both Gram-positive and Gramnegative bacteria; however, none of the hand soaps is effective against Pseudomonas aeruginosa. *Corresponding author: Email: [email protected] Introduction Tricolsan (2,4,4’trichloro-2’hydroxydiphenylether) is a broad spectrum antibiotic commonly used in a wide variety of domestic products as an antiseptic and anti-plaque agent. (1) Triclosan is present in antibacterial soaps, toothpastes, mouthwashes, cosmetics, deodorants, first-aid products and many commonly used house-hold items. In fact, 75% of liquid soaps and nearly 30% of bar soaps contain anti-microbial agents, the most common of which is triclosan. (2) In Sweden alone, 25% of toothpastes sold to consumers contain triclosan. (3) Triclosan works by blocking the active site of the enol-acyl carrier protein reductase enzyme (ENR) which is essential in the synthesis of fatty acids in bacteria. (4) Binding of triclosan to this enzyme increases the affinity of the enzyme for NAD, resulting in the formation of ENR-NAD+ triclosan complex which is unable to participate in the synthesis of fatty acids. (4) Since humans do not have this enzyme, tricolosan is believed to be relatively safe for humans. (4) Although ticlosan possesses mostly anti-bacterial IHE: Lincoln University Journal of Science; Vol.2 (1) 2011 properties, it is also thought to have some antifungal and anti-viral properties. (5) Consequently, triclosan is also used in hospitals for preventing hospital acquired infections, (6) and for decolonizing patients whose skins have methicillin resistant Staphylococcus aureus. (7) In spite of the effectiveness of triclosan in inhibiting microbial growth in commonly used domestic products and in controlling nosocomial infections, there is a growing concern that the overuse of triclosan may lead to potential dangers to humans and the environment. For example, the American Medical Association is concerned that despite the proliferation of triclosan in consumer products, its use has not been extensively studied. (8) Studies have shown that some bacteria including Staphylococcus aureus and Escherichia coli can develop low resistance to tricolosan due to Fab1 mutation. (9) Pseudomonas aeruginosa also possesses multi-drug efflux pump that pumps triclosan out of the cell, (10) and Bacillus species have alternative Fab1 genes to which triclosan does not bind. (11) These studies therefore indicate that the use of triclosan as an antimicrobial agent may not be justified for a wide variety of bacteria. Some studies even conclude that triclosan-induced-resistant bacteria are also resistant to other drugs including those used for the treatment of tuberculosis. (12) Some studies suggest that adding triclosan to river water and shining ultraviolet light on the water results in the formation of dioxin. (13, 14) There is therefore concern that dioxin toxicity could lead to endocrine disruption and possible interference with the function of the thyroid hormones and estrogen. (14, 15) Triclosan has indeed been shown to block the metabolism of thyroid hormones. (16) Since 95% of the triclosan used in consumer products is disposed of in residential drains, and since wastewater treatment is ineffective for removing triclosan, a large amount of triclosan is expected to contaminate waterways. (17) The discharge of triclosan into waterways could also affect the structure and function of algal communities in stream ecosystems, thereby, leading to possible destruction of the balance of aquatic ecosystems. (18) These concerns have led the American Food and Drugs Administration to state that beyond the use of triclosan in toothpastes to prevent gingivitis, there is no evidence that triclosan provides extra benefits to health in other consumer products. (19) The Environmental Working Group scientists also reviewed multiple studies and concluded that the widespread use of triclosan did not give consumers increased germ-killing benefits. (20) Some studies even suggest that triclosan was much less effective than hand soap against surface bacteria. (21) Other studies stated that chlorheximide and povidone-iodine detergent preparations were significantly more effective than non-medicated soaps, but triclosan products were not. (22) In spite of these concerns, leading soap brands including Softsoap, Dial, and Bath and Body works are vigorously promoting the efficacy of triclosan as an anti-bacterial agent. It is therefore necessary to determine the antibacterial quality of triclosan-containing soaps. Our hypothesis is that the non-triclosan containing hand soaps are equally effective in killing bacteria as the tricolsan-containing soaps. IHE: Lincoln University Journal of Science; Vol.2 (1) 2011 Methods and materials Ten types of hand soaps were used in this study: four of the ten [Dial, DG Body, Careone, Soft soap] did not contain triclosan. Six of the ten hand soaps [Soft soap, Careone, DG body, Dial, Safeguard, Equaline] contained triclosan. Careone and DG body had the lowest concentration of triclosan at 0.115%; Soft soap, Dial and Equaline had triclosan concentration of 0.15%, and Safeguard had the highest concentration of triclosan at 0.25%. All types and brands of hand soaps were purchased from local grocery stores. Veal Infusion Agar was prepared by mixing 40 grams of Veal Infusion Agar powder with one liter of distilled water, and heating the mixture over a Bunsen burner until completely dissolved. 19 ml of the dissolved agar was pipetted into each of 50 screw-cap tubes which were then sterilized by autoclaving at 121oC for 15 minutes. The tubes were removed from the autoclave and placed into a 45oC water bath to prevent the solidification of the media. Dilutions of soap solutions were prepared in sterile distilled water to give stock solutions of 40%, 20%, 10%, 5% and 2.5%, and then, 1.0 ml of each soap dilution was added to the 19 ml of molten and cooled agar. The soap dilution and molten agar were gently mixed together to give a final soap concentration of 2, 1, 0.5, 0.25 and 0.125 percent. The mixtures of agar and soap solutions were then carefully poured into sterile Petri dishes and allowed to solidify. Control agar plates were also prepared with 1.0 ml of distilled water in place of the soap solution. All the bacterial cultures used in this study were purchased from Wards Natural Science, Rochester, New York. Cultures of Escherichia coli (85 W 1660), Pseudomonas aeruginosa (85 W 1903), Salmonella typhimurium (85 W 1956), Bacillus cereus (85 W 1615), and Staphylococcus aureus (85 W 1941) were inoculated into tubes of Veal Infusion Broth and incubated at 37°C overnight. The broth culture of each bacterium was diluted in saline to McFarland 0.5. The soap infused agar and control agar were then inoculated with a loop-full of each culture. The five bacteria samples were streaked on each agar plate in parallel rows. Plates were incubated overnight at 37⁰C. Microbial growth was observed the following day and results were recorded. Heavy growth of the test bacteria on the soap containing media was indicated as three pluses; moderate growth was indicated as two pluses; light growth was indicated as one plus while no growth was recorded as NG. soaps were effective against Bacillus cereus at concentrations of 1% and 2% and DG Body only killed Staphylococcus aureus at a concentration of 2% (Table 1). Table 2 shows the summary of the results with triclosan-containing hand soaps. The results show that irrespective of the concentration of the hand soap, none of the hand soaps under test killed Pseudomonas aeruginosa. In fact there was profuse bacterial growth in all the plates. However, all six triclosan containing hand soaps were effective at all concentrations against Salmonella typhimurium, Escherichia coli and Staphylococcus aureus. Bacillus cereus was also killed at all concentrations by Soft soap and Safeguard; however, Careone, DG Body and Dial were only effective against Bacillus cereus if the soap concentration was at least 0.5%. Based on the results, we can state that the triclosancontaining hand soaps were more effective against the test bacteria than the non-triclosancontaining hand soaps. Results The results of this study are shown in Table 1 (non-triclosan containing hand soaps) and Table 2 (triclosan containing hand soaps). The results show that all the non-triclosan containing hand soaps were not effective against the three Gramnegative bacteria (Pseudomonas aeruginosa, Escherichia coli and Salmonella typhimurium. Dial, Careone and Soft soap were also not effective against one of the Gram-positive bacteria, Staphylococcus aureus. All four hand Table 1: Antibacterial activity of non-triclosan containing hand soaps Hand soap Dial Concentration Percent 2.0 1.0 0.5 0.25 0.125 Psudomonas aeruginosa +++ +++ +++ +++ +++ Salmonella typhimurium +++ +++ +++ +++ +++ Escherichia coli +++ +++ +++ +++ +++ Bacillus cereus NG NG NG + +++ Staph aureus +++ +++ +++ +++ +++ DG Body 2.0 1.0 0.5 0.25 0.125 +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ NG NG NG + +++ NG + + +++ +++ Careone 2.0 1.0 0.5 0.25 0.125 +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ +++ NG NG + +++ +++ + ++ ++ +++ +++ 2.0 +++ +++ +++ 1.0 +++ +++ +++ 0.5 +++ +++ +++ 0.25 +++ +++ +++ 0.125 +++ +++ +++ +++ [Heavy growth]; ++ [moderate growth]; + [light growth]; NG [No growth] NG NG NG ++ +++ ++ ++ +++ +++ +++ Soft soap IHE: Lincoln University Journal of Science; Vol.2 (1) 2011 Table 2: Antibacterial activity of triclosan containing hand soaps Hand soap Concentration Percent 2.0 1.0 0.5 0.25 0.125 Psudomonas aeruginosa +++ +++ +++ +++ +++ Salmonella typhimurium NG NG NG NG NG Escherichia coli NG NG NG NG NG Careone 2.0 1.0 0.5 0.25 0.125 +++ +++ +++ +++ +++ NG NG NG NG NG NG NG NG NG NG NG NG NG + + NG NG NG NG NG DG Body 2.0 1.0 0.5 0.25 0.125 +++ +++ +++ +++ +++ NG NG NG NG NG NG NG NG NG NG NG NG NG + +++ NG NG NG NG NG Dial 2.0 1.0 0.5 0.25 0.125 +++ +++ +++ +++ +++ NG NG NG NG NG NG NG NG NG NG NG NG NG NG ++ NG NG NG NG NG Safeguard 2.0 1.0 0.5 0.25 0.125 +++ +++ +++ +++ +++ NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG 2.0 +++ NG NG 1.0 +++ NG NG 0.5 +++ NG NG 0.25 +++ NG NG 0.125 +++ NG NG +++ [Heavy growth]; ++ [moderate growth]; + [light growth]; NG [No growth] NG NG NG NG + NG NG NG NG NG Soft soap Equaline Discussion The results of this study show that triclosancontaining hand-soaps are more effective antibacterial agents than non-triclosan containing hand soaps. The only exception among the test bacteria is Pseudomonas aeruginosa that was not killed by any of the hand soaps. Studies have shown that Pseudomonas aeruginosa possesses multi-drug efflux pump that pumps triclosan out of the cell. (10) It is therefore possible that the resistance of this bacterium to triclosan results from this mechanism. Overall, no hand soap is effective against Pseudomonas irrespective of whether it contains triclosan; therefore, other methods must be used in its killing especially in hospital environments. All triclosan containing hand IHE: Lincoln University Journal of Science; Vol.2 (1) 2011 Bacillus cereus NG NG NG NG NG Staph aureus NG NG NG NG NG soaps are effective against Salmonella typhimurium, Escherichia coli, Staphylococcus aureus and Bacillus cereus as long as the concentration of triclosan is above 0.5%. It is therefore recommended that hand soaps should be used above this concentration in order to kill bacteria such as Bacillus cereus. This study also showed that irrespective of the concentration of triclosan in the hand soaps, the antibacterial effect was identical. For example, there was no significant difference between Safeguard with 0.25% triclosan and Careone and DG Body with 0.115% tricosan. Since there are concerns regarding the overuse of triclosan in domestic products, the results of this study show that the concentration of triclosan can be reduced by half without losing its anti-bacterial qualities. This will reduce the amount of triclosan being discharged into wastewater that eventually pollutes waterways. (17) Finally, the results of this study contradict the views of the American Medical Association, (8) and the Food and Drugs Administration (19) that triclosan does not provide extra health benefits to consumers outside of their use in toothpastes to control gingivitis. The concern should be in controlling the concentration of triclosan in domestic products to avoid the problems of overuse and abuse. 9. 10. References 1. 2. 3. 4. 5. 6. 7. 8. Braid JJ and Wale MCJ. The antibacterial activity of triclosan-impregnated boxes against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus and Shewanella putrefaciens in conditions simulating domestic use. Journal of Antimicrobial Chemotherapy. 2002; 49: 87-94. FSNET. 2000. Survey of US stores reveals widespread availability of soaps containing potentially harmful antibacterial agents. Center for safe food, University of Guelph. [Online][September 9, 2000]. Available: http://131.104.74.73/archives/fsnet/2000/9 -2000/fs-09-10-00-01.txt Adolfsson-Erici M, Pettersson M, Parkkomen J, Sturve J. Triclosan, a commonly used bactericide found in human milk and in the aquatic environment in Sweden. Chemosphere. 2002; 46: 14851498. Levy CW, Roujeinikovai A, Sedelnikova S, Baker PJ, Stuitje AR, Slabas AR, Rice DW, Rafferty JB. Molecular basis of triclosan activity. Nature. 1999; 398: 383-384. Lurie Z. Engaging in germ warfare. Journal Gazette. [Online][August 2, 2004]. Available on: http://www.fortwayne.com/mld/journal gazette/929628.htm Levy SB. Antimicrobial consumer products. Archives of Dermatology. 2002; 138: 10871088. Coia JE, Duckworth GJ, Edwards DI, Farrington M, Fry C, Humphreys H, Mallaghan C, Tucker DR. Guidelines for the control and prevention of methicillinresistant Staphylococcus aureus (MRSA) in healthcare facilities. Journal of Hospital infections. 2006; 63 (Supplement 1): S1 – 44. Tan L, Nielsen NH, Young DC, Trizna Z. Use of antimicrobials in consumer products. IHE: Lincoln University Journal of Science; Vol.2 (1) 2011 11. 12. 13. 14. 15. 16. 17. 18. Report 2 of the Council on Scientific affairs. Arch Dermatol. 2002; 138 (8):1082-1086. Heath RJ, Rubin JR, Holland DR, Zhang E, Snow ME, Rock CO. Mechanisms of triclosan inhibition of bacterial fatty acid synthesis. J. Biol Chem. 1999; 274: (16): 11110 – 111104. Fan F, Yan K, Wallis NG, Reed S, Moore TD, Rittenhouse SF, DeWolf WE Jr, Huang J, McDevitt D, Miller WH, Seefeld MA, Newlander KA, Jakas DR, Head MS, Payne DJ. Defining and combating the mechanisms of triclosan resistance in clinical isolates of Staphylococcus aureus. Antimicrobial Agents of Chemotherapy. 2002; 46 (11): 3343 – 3347. Chuanchuen R, Karkhoff-Schwezer RR, Schweizer HP. High level of triclosan resistance in Pseudomonas aeruginosa is solely a result of efflux. American Journal of Infection control. 2003; 31 (2): 124-127. Levy SB. Antibacterial household products: cause for concern. Emerging Infectious Diseases. 2001; 7 (3, supplement): 512-515. Latch DE, Packer JL, Arnolda WA, McNeill K. Photochemical conversion of triclosan to 2,8-dichlorodibenzo-p-dioxin in aqueous solution. Journal of Photochemistry and Photobiology A: Chemistry. 2000; 158 (1): 63-66. Rule KL, Ebbett VR, Vikesland PJ. Formation of chloroform and chlorinated organics by free chlorine mediated oxidation of triclosan. Environmental Science Technology. 2005; 39 (9): 3176-3185. Inglis A. Antibacterial products aren’t just useless – they can be killers. [Online] [May 5, 2009] [Accessed April 6, 2010]. Available on: http://www.healthiertalk.com/antibacterialproducts-aren-t-just-useless-they-can-bekillers-0595 Veldhoen N, Skirrow RC, Osachoff H, Wigmore H, Clapson DJ, Gunderson MP, Van Aggelen G, Helbing CC. The bacterial agent triclosan modulates thyroid hormoneassociated gene expression and disrupts postembryonic anuran development. Aquatic toxicology. 2006; 80 (3): 217-227. Reiss R, Mackay N, Habig C, Griffin J. An ecological risk assessment for triclosan in lotic systems following discharge from wastewater treatment plants in the United States. Environmental Toxicology and Chemistry. 2002; 21 (11): 2483-2492 Wilson BA, Smith VH, deNoyelles Jr. F, Larive CK. Effects of three pharmaceutical and personal care products on natural freshwater algal assemblages. Environmental Science and Technology. 2003; 37 (9): 162A – 164A. 19. Triclosan: what consumers should know. US Food and Drug Administration. [Online] [April 8, 2010]. Available from: http://www.fda.gov/ForConsumer/Consum er Updates/ucm205999.htm 20. Environmental Working Group. EPA needs to protect people and the environment from contamination with antimicrobial pesticides. [Online] [April 6, 2009]. Available from: http://www.ewg.org/reports/triclosan 21. Namura S, Nishijuma S, McGinley KJ, Leyden JJ. A study of the efficacy of antimicrobial detergents for hand washing: suing the full-hand touch plates method. J. Dermatol. 1993; 20 (2): 88-93. 22. Ayliffe GA, Babb JR, Davis JG, Lilly HA. Hand disinfection: a comparison of various agents in laboratory and ward studies. J. Hosp Infect. 1988; 11 (3): 226-243. IHE: Lincoln University Journal of Science; Vol.2 (1) 2011 IHE: Lincoln University Journal of Science; Vol.2 (1) 2011