Alcohol Sanitizer

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan.


Maintaining hand hygiene has been established as crucial for reducing the colonization and incidence of infectious diseases in all populations. Compliance with hand hygiene recommendations is believed to play a significant role in decreasing the risk of gastroenteric and respiratory infections. Strict hand hygiene is even more important for health-care workers (HCW) as unclean hands may aid in the transmission of microorganisms from patient to patient, leading to increased morbidity, mortality, and costs associated with healthcare-associated infections (HCAI). In 2002, healthcare-associated infections (HCAI) were a cause of 99,000 deaths in the United States of America, and the 2004 annual economic impact of HCAI was estimated to be US$ 6.5 billion.

Evidence suggests that hand sanitization significantly reduces the transmission of healthcare-associated pathogens and the incidence of HCAI. Despite the emphasis on the importance of hand hygiene, recent studies show poor hand hygiene compliance in medical settings. According to the Center for Disease Control and Prevention (CDC), hand hygiene encompasses the cleansing of your hands using soap and water, antiseptic hand washes, alcohol-based hand sanitizers (ABHS), or surgical hand antiseptics. These days, alcohol-based hand sanitizers are increasingly being used instead of soap and water for hand hygiene in healthcare settings. Their ease of use increased availability, and proven effectiveness are some of the reasons why alcohol-based hand sanitizers are gaining popularity. In one study, a hospital-wide hand hygiene campaign with special emphasis on bedside alcohol-based hand disinfection resulted in sustained improvement in hand-hygiene compliance, coinciding with a reduction of nosocomial infections and MRSA transmission. A systematic review also demonstrated with moderate certainty that having bedside alcohol-based solutions increased compliance with hand hygiene among HCWs.

It is, however, important to keep in mind that the efficacy of alcohol hand sanitizers is dependent upon the type of alcohol, the quantity applied, the technique used, and the consistency of use. There are also situations where these products are not ideal, for example, in preventing the spread of certain alcohol-resistant infections or when hands are significantly soiled and the bacterial load is too high.

Alcohol-based (hand) Rub

The World Health Organization (WHO) defines an alcohol-based hand rub as: "An alcohol-containing preparation (liquid, gel or foam) designed for application to the hands to inactivate microorganisms and/or temporarily suppress their growth. Such preparations may contain one or more types of alcohol, other active ingredients with excipients, and humectants.”

Alcohol-based hand antiseptics mostly contain isopropanol, ethanol, n-propanol, or a mixture of these as their active ingredients. The antimicrobial activity of alcohols is attributed to their ability to denature and coagulate proteins. This causes microbes to lose their protective coatings and become non-functional. The Center for Disease Control and Prevention recommends formulations containing 80% (percent volume/volume) ethanol or 75% isopropyl alcohol, however, generally speaking, sanitizers containing 60 to 95% alcohol are acceptable. The recommended percentages of ethanol and isopropyl alcohol are kept as 80% and 75% because these values lie in the middle of the acceptable range. Notably, higher than recommended concentrations are also paradoxically less potent because proteins are not denatured easily without the presence of water. Alcohol concentrations in antiseptic hand rubs are often expressed as percent by volume and rarely as percent by weight. A study conducted on 85% (weight/weight) ethanol, showed that a 15 seconds contact time was enough to reduce gram-positive and negative bacteria by greater than 5 log10 steps. Research suggests that alcohols are swiftly germicidal when applied to skin, but have no noticeable persistent residual activity. However, it has been documented that the regrowth of bacteria does occur slowly after its use. This may be because of the sublethal effect alcohol may have had on the residual bacteria. Adding chlorhexidine, octenidine, or triclosan to alcohol-based hand rubs may result in somewhat persistent protection as well. 4% chlorhexidine has shown persistent bactericidal activity against methicillin-resistant Staphylococcus aureus for up to 4 hours from application.

Ethanol, the most common alcohol ingredient, appears to be the most effective alcohol against viruses, whereas, propanol is considered to be a better bactericidal alcohol. The combination of alcohols may also have a synergistic effect. The concentration of alcohol in hand sanitizers also changes its efficacy, with one study demonstrating that a hand rub with 85% ethanol content was significantly better at reducing bacterial populations compared to preparations of 60% to 62% ethanol. ABHS also often contain humectants, like glycerin, which help prevent skin dryness, and emollients or moisturizers, like aloe vera, which help replace some of the water that is stripped off during use. None of the above-mentioned alcohols have shown a potential for acquired bacterial resistance, and are therefore considered highly effective for repeated use in medical settings.

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