Compliance with hand hygiene recommendations is critical to reducing colonization and infection of the hands of all people, and specifically the hands of health-care workers (HCW). This will decrease transmission of microorganisms to patients, ultimately reducing morbidity, mortality, and costs associated with healthcare-associated infections (HCAI). The global burden of HCAI is enormous. Data suggests that more than 1.4 million patients in developed and developing countries worldwide are affected at any time. There is ample evidence that hand antisepsis reduces the transmission of healthcare-associated pathogens and the incidence of HCAI.
Even after so much emphasis on the importance of hand hygiene, recent studies show poor hand hygiene compliance in the medical setting. In a 2017 study of healthcare professionals in an emergency department, the compliance rate was only 54%. In a survey of EMS providers regarding hand hygiene practices, compliance was even lower.
According to the Center for Disease Control (CDC) hand hygiene encompasses the cleansing of your hands by using hand washing with soap and water, antiseptic hand washes, antiseptic hand rubs such as alcohol-based hand sanitizers (ABHS), foams or gels, or surgical hand antisepsis. For many reasons, alcohol hand sanitizers are increasingly being used as disinfectants over hand washing with soap and water. Their ease of availability, no need for water or plumbing, and their proven effectiveness in reducing microbial load are just a few. In one study, a hospital-wide, hand hygiene campaign with special emphasis on bedside, alcohol-based hand disinfection resulted sustained improvement in hand-hygiene compliance, coinciding with a reduction of nosocomial infections and MRSA transmission. The promotion of bedside, antiseptic, hand rubs largely contributed to the increase in compliance. Many other studies have demonstrated that having bedside alcohol-based solutions availabale increased compliance with hand hygiene among HCWs.
However, it is important to keep in mind that alcohol hand sanitizer efficacy is dependent upon which and how much product is used, proper technique, and consistency of use. There are also situations where these products are not ideal, for example, in preventing the spread of certain infections or when the hands are significantly soiled and the bacterial load is too high.
Non-Alcohol-Based Hand Sanitizers
Benzalkonium cChloride, a quaternary ammonium, is the active ingredient contained in most alcohol-free hand sanitizer products available today. It is non-flammable, and the low concentrations of bBenzalkonium make it relatively non-toxic. Typically, these solutions, often water-based foams, are much easier on the hands and continue to provide protection well after the solution has dried. They pose much less of a threat in cases of accidental ingestion or as a potential fire hazard and are non-damaging to surfaces. However, alcohol-free products have yet to gain a foothold in the health market. Alcohol-based gels are favored by most health organizations and are therefore perceived as being more credible.
Alcohol-based (hand) rub
According to the World Health Organization (WHO), "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."
Most alcohol-based hand antiseptics contain isopropanol, ethanol, n-propanol, or a combination of 2 of these products. The antimicrobial activity of alcohols can be attributed to their ability to denature and coagulate proteins. The microorganism’s cells are then lysed, and their cellular metabolism is disrupted. Alcohol solutions containing 60% to 95% alcohol are most effective. Notably, higher concentrations are less potent because proteins are not denatured easily in the absence of water. Alcohol concentrations in antiseptic hand rubs are often expressed as percent by volume, but sometimes as percent by weight.
Alcohols such as ethanol are well-known antimicrobial agents and were first recommended for the treatment of hands in 1888. The highest antimicrobial efficacy can be achieved with ethanol (60% to 85%), isopropanol (60% to 80%), and n-propanol (60% to 80%). The activity is broad and immediate. Ethanol, the most common alcohol ingredient, appears to be the most effective against viruses; whereas, the propanols have better bactericidal activity than ethanol. None of the alcohols has shown a potential for acquired bacterial resistance. The combination of alcohols may have a synergistic effect. The concentration of alcohol does change the efficacy, with one study showing a hand rub with 85% ethanol being significantly better at reducing bacterial populations compared to concentrations of 60% to 62%. 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 by the alcohol.
ABHS are very effective for quickly destroying many pathogens by the action of the aqueous alcohol solution without the need for water or drying with towels. According to the Centers for Disease Control and Prevention (CDC), alcohols have excellent in vitro germicidal activity against gram-positive and gram-negative vegetative bacteria, including multidrug-resistant pathogens (MRSA, VRE), Mycobacterium tuberculosis, HIV, influenza virus, RSV, vaccinia, and hepatitis B and C viruses. Numerous studies have also documented the in vivo antimicrobial activity of alcohols, including effectiveness in removing clinical strains of Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans from heavily contaminated hands of human volunteers.
ABHS are tremendously effective in preventing the spread of the seasonal flu, H1N1, URI, and other viral-based and bacterial-based diseases. Ethanol hand sanitizers were significantly more effective than hand washing with soap and water for removal of detectable rhinovirus, the most frequent cause of the common cold, from hands. One concern is that the antimicrobial effect of ABHS is very short lived. The addition of organic acids to the ethanol provided residual virucidal activity that persisted for at least 4 hours. Whether these treatments will reduce rhinovirus infection in the natural setting remains to be determined.
A study published in 2017 in the Journal of Infectious Diseases evaluated the virucidal activity of ABHS against re-emerging viral pathogens, such as Ebola virus, Zika virus (ZIKV), severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV) and determined that they and other enveloped viruses could be efficiently inactivated by both WHO formulations I and II (ethanol-based and isopropanol-based respectively). This further supports the use of ABHS in healthcare systems and viral outbreak situations.
Another advantage to using ABHS is that they are often less irritating to the hands. Excessive hand washing with soap and water can cause skin damage and increase the risk for infections. Drying hands with a towel removes pathogens first by friction during rubbing with the drying material and then by wicking away the moisture into that material. The CDC recommends the use of alcohol-based hand rubs containing various emollients and other skin conditioners instead of irritating soaps and detergents as a strategy to reduce skin damage, dryness, and irritation. Damage to the skin can change the skin flora, resulting in more frequent colonization by staphylococci and gram-negative bacilli. Irritant contact dermatitis was lowest with well-formulated, alcohol-based hand rubs containing emollients and other skin conditioners when compared to other methods of hand hygiene according to several studies. This is especially true for healthcare workers, who may wash their hands more than 30 times per shift. Nevertheless, it is recognized that even products containing emollients along with the alcohol may cause a momentary stinging sensation if there are any cuts or abrasions present on the hands. Allergic contact dermatitis associated with alcohol-based hand rubs is uncommon.
Some have posed the question of possible health effects related to unintentional alcoholization (via inhalation and dermal contact) from professional frequent ABHR usage, suggesting the need for more research in this area.
ABHS have not been shown to be as effective as good soap and water hand washing against certain infections. For instance, alcohols have very poor activity against protozoan oocysts, certain non-enveloped (non-lipophilic) viruses, and bacterial spores.
Cryptosporidium, a waterborne parasite, is the leading cause of waterborne disease outbreaks and is a frequent cause of diarrhea outbreaks in daycares. Once infected, people with decreased immunity are most at risk for severe disease. According to the CDC, alcohol-based hand sanitizers are not effective against Cryptosporidium.
Norovirus is the leading cause of illness and outbreaks from contaminated food in the United States. According to the CDC, over 90% of diarrheal disease outbreaks on cruise ships are caused by norovirus. Most outbreaks of norovirus illness happen when infected people spread the virus to others. Healthcare facilities, including nursing homes and hospitals, are the most commonly reported settings for norovirus outbreaks in the United States and other industrialized countries, especially in long-term care facilities. Studies have demonstrated that ABHS are often ineffective against non-enveloped viruses, including norovirus. One study even found an association between the preferential use of ABHS for routine hand hygiene with an increased risk for outbreaks of norovirus. However, ethanol-based hand rubs have been effective against norovirus surrogates even at lower concentrations, when different types of acids are added to the hand rub. Also, the efficacy of alcohol-based hand rubs against noroviruses varies with type and concentration of alcohol in the formulation. WHO experts still do recommend the use of alcohol-based hand rubs during outbreaks of noroviral gastroenteritis.
There are exceptions regarding alcohol-based hand rub in vivo inactivity against non-enveloped viruses. Studies have found that alcohol sanitizers do reduce the infectivity titers of 3 non-enveloped viruses (rotavirus, adenovirus, and rhinovirus) and in higher concentrations of hepatitis A and enteroviruses.
A recent review found that ethanol at 80% is unlikely to sufficiently destroy poliovirus, polyomavirus, calicivirus (FCV), hepatitis A virus (HAV) and foot-and-mouth disease virus (FMDV). However, at 95%, the spectrum of virucidal activity of ethanol covers the majority of clinically relevant viruses. Additional acids can substantially improve the virucidal activity of ethanol at lower concentrations against, e.g., poliovirus, polyomavirus, FCV, and FMDV although some viruses like HAV may still be too resistant. The issue is the tolerability of ABHS at higher alcohol concentrations.
Alcohol gel kills the vegetative cell form of Clostridium difficile but does not kill C. difficile spores. Several studies have found hand washing with soap and water to be more effective at removing C. difficile spores than ABHS from the hands of volunteers inoculated with a known number of C. difficile spores. However, there are no studies in acute care settings that have demonstrated an increase in C. difficile infection with alcohol hand sanitizer use or a decrease in C. difficile infection with soap and water. Wearing gloves, and then removing them properly to prevent hand contamination in the removal process, is of paramount importance in preventing the spread of C. difficile infection, and likely negates any potential benefit of using soap and water over alcohol-based hand hygiene products.
ABHS were found to be less effective compared to other methods of hand hygiene in removing E. coli and other microorganisms (caliciviruses) underneath fingernails. This is especially true with longer nails and artificial fingernails, which reportedly harbor higher microbial populations than natural nails.
Interestingly, a study of farm workers demonstrated that those who used hand sanitizer were found to have elevated concentrations of urinary pesticide metabolites, whereas washing hands with water was not associated with this.
Efficacy is also very dependent on the technique of application of the alcohol hand sanitizer. One must apply the product to the palm and rub the product all over the surfaces of both hands until they are dry. There have been several studies comparing the amount needed to be effective (2.4 to 3 mL is recommended) and application time required to achieve hand disinfection (25 to 30 seconds). Dispensers may deliver considerably less than 3 mL of hand rub if pushed only once, which would be insufficient to cover the hands entirely.
Foams containing 62% ethanol are used for hand decontamination in many countries. They require a long drying time, which may reduce the compliance of healthcare workers in applying the recommended amount of foam. One study found that the time required for dryness often exceeded the recommended 30 seconds. Therefore, to quicken the process, only a small volume is likely to be applied in clinical practice, and small amounts failed to meet the efficacy requirements and were only somewhat more effective than water.
Another study found that high-quality hygienic hand disinfection is not possible within 15 seconds and that a 30-second application time of ABHS is recommended. Thirty seconds is a long time to wait before proceeding with the activity one was setting out to do after disinfection, in fact, about the same time as washing with soap and water. The study also compared techniques of applying the alcohol rub, including a 6-step method, and found that “responsible application” was adequate, as long as people are made aware that they are responsible for covering their entire hands during hygienic hand disinfection.
A concern about using ABHS that is not a concern for soap and water is unintended pediatric ingestions. Ethanol-based hand sanitizers can cause alcohol poisoning if a person swallows more than a couple of mouthfuls. US poison control centers received nearly 85,000 calls between 2011 and 2015 about hand sanitizer exposures among children. Several studies have found that the ingestion of ethanol from hand sanitizers can induce intoxication and hypoglycemia in children. Older children have been known to swallow hand sanitizers to become drunk purposefully.
The use of alcohol-based hand sanitizers has greatly increased compliance to hand hygiene in healthcare settings. They are efficient, accessible, and take relatively little time to use. Even though there are some situations where they are perhaps less effective than standard soap and water, if using ABHS will result in more consistent hand hygiene, it may be worth that trade-off. If it is known that there is potential exposure to microorganisms that are less responsive to alcohol-based hand sanitizers or the hands are heavily soiled, then soap and water (or both methods) may be the preferred way to go.