he best way to stay healthy and avoid getting sick is to wash your hands. Some of the most recent scientific evidence comes from a study of hospital-acquired methicillin-resistant Staphylococcus aureus infection. Methicillin-resistant Staphylococcus aureus (MRSA or “staph”) is a bacteria that can enter the body through breaks in the skin and cause severe infections and even death, especially in people who are already sick. MRSA represents a major control problem in hospitals as it has developed a resistance to all penicillins, including methicillin and other narrow-spectrum beta-lactamase-resistant penicillin antibiotics [1]. Researchers concluded at the end of the study that hospitals could greatly limit the spread of MRSA through the use of increased barrier protection (gloves) by workers and more frequent hand washing [2].
Soap, antimicrobial soap and alcohol-based hand antiseptic
Essentially everything we call dirt is either oily or is stuck to us with oil. What makes soap unique is the ability to remove oil. Soap is a surfactant (or surface active agent, meaning a wetting agent that lowers the surface tension of a liquid) used in conjunction with water for washing and cleaning. Many soaps are a mixture of sodium or potassium salts of fatty acids, derived from oils or fats by reacting them with sodium or potassium hydroxide. A soap molecule has a hydrophilic (meaning attracted to water) carboxylate “head” and long hydrophobic (meaning repelled by water) hydrocarbon “tail”. In water, soap molecules arrange themselves into tiny clusters called micelles. The hydrophilic head of each soap molecule faces outwards, forming the outer surface of the micelle. The hydrophobic tails group together on the inside. This micelle structure allows soap to adhere to substances that are otherwise insoluble in water (oil), trapping them in the hydrophobic center. The hydrophilic head of each soap molecule on the outer surface of the micelle attaches easily to polar molecules (meaning that one end of the molecule is more positively charged while the other is more negatively charged) such as water, allowing it to be flushed away with other water molecules. Additionally, soap molecules disrupt the surface tension of water by crowding around the water’s surface. The reduction in surface tension allows water to spread and wet surfaces. For this reason, surfactants are often said to “make water wetter”.
Plain soaps (non-antibacterial) have minimal microbial activity and may be associated with considerable skin irritation and dryness [3-4]. Soap has an alkaline pH between 9-10 and efficiently removes both sebum (meaning an oily substance secreted by sebaceous glands found in the skin that acts to protect and waterproof the hair and skin, and keep them from becoming dry, brittle and cracked) and epidermal lipids (meaning hydrocarbon-containing organic compounds; in living organisms, lipids serve as structural components of cell membranes) that have combined with keratin protein to form the epidermal lipid barrier.
Synthetic detergents or soap-free cleansers remove less sebum and fewer epidermal lipids as they have a more neutral pH (5.5-7) than soap. The more neutral the pH, the less likely that the cleanser will dry and damage your skin. However, synthetic detergents frequently contain petroleum-based surfactants such as diethanolamine (DEA) and sodium dodecylbenzensulfon
ate, which can be skin and eye irritants. The Household Products Database of the National Library of Medicine is an excellent resource to research products based on chemical ingredients.
Antimicrobial soap contains antimicrobial chemicals such as triclosan or alcohol. Other antiseptic agents include chlorhexidine, chloroxylenol, hexachlorophene, iodine and iodophors and quaternary ammonium compounds, which are beyond the scope of this article. Triclosan, developed in the 1960s, has antimicrobial activity at concentrations of 0.2-2%. At low concentrations, triclosan is bacteriostatic (meaning it stops bacterial growth), while higher concentrations are bactericidal (meaning it kills bacteria) [5]. Introduction of triclosan-containing hand wash disinfectant to hospital workers has been shown to decrease MRSA infections [6]. However, the results of a double-blinded, randomized clinical trial comparing the short- and long-term effects of hand washing with plain or antimicrobial soap over the course of a year argue in favor of targeted rather than ubiquitous general household use of antimicrobial soap [7].
The American Medical Association took an official stance against adding antimicrobials to consumer products in 2000 and has repeatedly urged the Food and Drug Administration (FDA) to better regulate these chemicals [8]. In 2005, the Soap and Detergent Association and The Cosmetic, Toiletry, and Fragrance Association told a FDA advisory panel that antibacterial hygiene products play an invaluable role in the lives of consumers. Nonetheless, the advisory panel concluded that popular antibacterial soaps and washes were no more effective at preventing illness than plain — and less expensive — soap and water [9]. However, the regulatory status of antimicrobial soaps has yet to be finalized.
Most alcohol-based hand antiseptics contain either isopropanol, ethanol, n-propanol or a combination of the two. The antimicrobial activity of alcohol can be attributed to its ability to denature proteins. Alcohol solutions containing 60-95% alcohol are more effective than concentrations approaching 100% because proteins are not easily denatured in the absence of water [10]. Alcohols are germicidal when applied to the skin, effectively reducing bacterial counts on the hands, but have no residual activity. Nevertheless, bacterial regrowth occurs slowly on the skin after use of alcohol-based hand antiseptics [11]. Alcohol-based antiseptics should not be used when hands are visibly dirty or contaminated with proteinaceous material. Frequent use can cause drying of the skin; however, this can be reduced by the inclusion of emollients, humectants or other skin-conditioning agents in the formulation [12].
In contrast to non-antibacterial soap, which simply separates bacteria from your hands, antibacterial soap kills most bacteria on your hands immediately. However, a few bacteria will survive and with repeated exposure become resistant to the antibacterial compound(s). Years ago, antibacterial soaps were primarily used in clinical health care environments. Today however, the majority of all liquid soap sold in the United States contains antibacterial ingredients.
A randomized controlled trial to assess the effect of handwashing promotion with soap on the incidence of acute respiratory infection, impetigo, and diarrhea in children was recently done [13]. The study results are enlightening: children younger than 5 years in households that received non-antibacterial soap and handwashing promotion had a 50% lower incidence of pneumonia than controls. Children younger than 15 years in households with non-antibacterial soap had a 53% and 34% lower incidence of diarrhea and impetigo (one of the most common contagious skin infection in children that produces blisters or sores on the face and hands), respectively. The incidence of disease did not differ significantly between household receiving non-antibacterial soap from those given antibacterial soap. In fact, in 2006 the Prevention and Incidence of Asthma and Mite Allergy Birth Cohort Study concluded that early exposure to common microbial contaminants, including fungal agents, may actually protect against asthma [14].
Hand washing and hand-hygiene techniques
Here are proper hand washing techniques that you can adopt into your daily routine to stay healthy and prevent getting sick.
1. Wet your hands and wrists with warm running water. Frequent handwashing with hot water is associated with the development of dermatitis [15-16].
2. Rub your hands, including the fingers, palm to palm in a circular fashion.
3. With palms still together, intertwine the fingers and rub in between them.
4. In a circular fashion, rub the back of each hand with the opposite palm, making sure not to ignore the knuckles and fingers.
5. Rub each thumb by gripping it with the opposite hand.
6. Rub each wrist by gripping it with the opposite hand.
7. Be sure that each part is washed for at least 20 seconds.
8. Rinse your hands and wrists thoroughly under warm running water. Keep your hands lower than your elbows to avoid water flowing up the arms and then back down onto the hands, contaminating them.
9. Dry your hands completely using a clean or disposable towel.
10. Using the towel, turn off the faucet. If in a public restroom, use the towel to grasp the door handle and open the door, then discard the towel.
CDC recommendations
The Centers for Disease Control and Prevention (CDC) says that of the two million hospital-acquired infections reported each year, 90,000 are fatal. Keeping hands clean is important both at home and at the hospital. Using a simple technique like hand washing is especially important for cancer patients whose immune systems are weakened and who are more susceptible to illness than the general population.
The CDC recommends:
1. Removing any rings or other jewelry
2. Wetting the hands with warm water
3. Applying soap
4. Rubbing hands together for at least 15 seconds
5. Scrubbing all surfaces, including:
* Backs of your hands
* Between your fingers and fingernails
* Wrists
6. Rinsing your hands
7. Drying thoroughly with a towel
8. Turning off the faucet using a paper towel
Or use an alcohol-based hand antiseptic:
1. Applying the alcohol product to one palm
2. Rubbing the hands together covering all surfaces until the skin is dry
Always wash your hands:
* Before eating
* After using the bathroom
* After changing a diaper ““ wash the diaper-wearer’s hands, too
* Before and after preparing food, especially before and immediately after handling raw meat, poultry or fish
* After touching animals or animal waste
* After blowing your nose
* After coughing or sneezing into your hands
* Before and after treating wounds or cuts
* Before and after touching or visiting a sick or injured person
* After handling garbage
* Before inserting or removing contact lenses
References
1. Foster, T. Staphylococcus. In: Barron’s Medical Microbiology (Barron et al., eds.), 4th ed. 1996 Univ of Texas Medical Branch.
2. Kac et al. Methicillin-resistant Staphylococcus aureus. Nosocomial acquisition and carrier state in a wound care center. Arch Dermatol. 2000 Jun;136(6):735-9.
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3. Larson et al. Physiologic and microbiologic changes in skin related to frequent handwashing. Infect Control. 1986 Feb;7(2):59-63.
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4. Boyce et al. Skin irritation and dryness associated with two hand-hygiene regimens: soap-and-water handwashing versus hand antisepsis with an alcoholic hand gel. Infect Control Hosp Epidemiol. 2000 Jul;21(7):442-8.
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5. Russell AD. Whither triclosan? J Antimicrob Chemother. 2004 May;53(5):693-5.
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6. Webster et al. Elimination of methicillin-resistant Staphylococcus aureus from a neonatal intensive care unit after hand washing with triclosan. J Paediatr Child Health. 1994 Feb;30(1):59-64.
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7. Larson et al. Short- and long-term effects of handwashing with antimicrobial or plain soap in the community. J Community Health. 2003 Apr;28(2):139-50.
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8. AMA reiterates call for FDA regulation of antimicrobials in consumer products. AMA. 2005 Oct.
9. Rubin R. Antiseptic soaps bubble up again. USA Today. 2005 Sept.
10. Larson and Morton. Alcohols [Chapter 11]. In: Block SS, ed. Disinfection, sterilization and preservation. 4th ed. Philadelphia, PA: Lea and Febiger, 1991:642-54.
11. Lilly et al. Delayed antimicrobial effects of skin disinfection by alcohol. J Hyg (Lond). 1979 Jun;82(3):497-500.
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12. Rotter et al. The influence of cosmetic additives on the acceptability of alcohol-based hand disinfectants. J Hosp Infect. 1991 Jun;18 Suppl B:57-63.
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13. Luby et al. Effect of handwashing on child health: a randomised controlled trial. Lancet. 2005 Jul 16-22;366(9481):225-33.
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14. Douwes et al. Does early indoor microbial exposure reduce the risk of asthma? The Prevention and Incidence of Asthma and Mite Allergy birth cohort study. J Allergy Clin Immunol. 2006 May;117(5):1067-73.
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15. Ohlenschlaeger et al. Temperature dependency of skin susceptibility to water and detergents. Acta Derm Venereol. 1996 Jul;76(4):274-6.
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16. Emilson et al. The temperature effect of in vitro penetration of sodium lauryl sulfate and nickel chloride through human skin. Acta Derm Venereol. 1993 Jun;73(3):203-7.
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