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Proper hand hygiene is one of the most critical factors in infection control. In a recent study, it was found that up to 25% of general practice dentists do not maintain adequate hand hygiene.1 Those who were more likely to report acceptable hand hygiene behavior were those with good to excellent knowledge of the Centers for Disease Control and Prevention (CDC) current guidelines for hand hygiene in healthcare and dental healthcare settings. These guidelines include the use of alcohol-based hand rubs as well as recommendations regarding hand hygiene-related issues, such as the use of hand lotions and wearing jewelry or artificial nails. In order to prevent the spread of infectious organisms during the course of dental treatment, it is not enough to enforce stringent antiseptic procedures on environmental surfaces; the first line of defense, especially with the increase of various drug-resistant species, is for every dental practitioner to ensure that their hands are as sterile as possible before beginning patient treatment.
A History of Hand Hygiene Guidelines
Cleaning the hands with some type of antiseptic agent as a means of maintaining good personal hygiene emerged in the early 19th century.2 The first real evidence that cleansing the hands with an antiseptic agent could prevent disease transmission occurred in the General Hospital of Vienna in the 1840s, where it was observed that washing the hands with a chlorine solution between patients significantly reduced maternal mortality rate after giving birth at the hospital.2
In the United States, the first formal guidelines on hand hygiene practices in hospital settings were published by the CDC in 1975 and 1985, where the emphasis was on washing hands with non-antimicrobial soap when in contact with most patients, reserving the use of antimicrobial soap for before and after invasive procedures or when caring for high-risk patients. Waterless antiseptic agents, such as alcohol-based solutions, were only recommended in situations where sinks were not available.3
In 1995, the Association for Professionals in Infection Control and Epidemiology (APIC) presented evidence that alcohol-based hand rubs could be beneficial as an adjunct to hand washing, and encouraged the use of these products in more clinical settings than had been previously recommended.3 The CDC then published guidelines, the 2002 Guideline for Hand Hygiene in Healthcare Settings and the 2003 Guidelines for Infection Control in Dental Health-Care Settings, that also promoted the use of alcohol-based hand rubs in improving hand hygiene practices, and made recommendations regarding hand hygiene-related issues that had not been addressed before, such as the use of hand lotions, and wearing of hand jewelry or artificial nails (Table 1).3,4
The Physiology of Skin
The main role of skin is to act as a barrier: a barrier to the environment, a barrier against microorganisms, and a barrier to excessive water loss from the body. Skin consists of four layers: a top layer called the stratum corneum (10 μm to 20 μm thick), the epidermis (50 μm to 100 μm thick), the dermis (1 mm to 2 mm thick) and the hypodermis (1 mm to 2 mm thick). The intercellular region of the stratum corneum is composed of lipids, such as glycerolipids and sterols, which are necessary for skin to act as a competent barrier.3 Studies have found that the skin barrier can be disrupted by products that cause chemical irritation and by the use of solvents (such as alcohol-based hand rubs) and detergents (such as soap), because they remove lipids from the skin.5 Complete normalization of barrier function requires 5 to 6 days. The skin also has minute openings called dermal ducts, via which pathogenic organisms in blood, saliva, and dental plaque can enter the body.3,4
Microorganisms on and in the Skin
The skin harbors two types of bacterial flora: resident and transient.6 Resident flora colonize skin, becoming permanent residents, and even existing in deeper layers of skin. They are not typically associated with infections. Transient flora, on the other hand, do not typically colonize skin and cannot survive on skin for very long, but they are most frequently associated with healthcare-associated infections. Transient flora contaminate the hands through contact with patients, surfaces, or instruments, and remain on the outer surface of skin, where they can be removed by routine hand washing.7,8 Superbugs, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), are usually transient flora on skin, but have been known to colonize the skin in some cases.9,10 Total bacterial counts on the hands of healthcare workers has ranged from 3.9 X 104 to 4.6 X 106.3,11
Hand Hygiene for Dental Healthcare Workers
The evidence is overwhelming that hand antisepsis reduces the incidence of healthcare associated infections.11 The preferred method for hand hygiene—whether hand washing, hand antispesis, or surgical hand antispesis—depends on the type of procedure, the degree of contamination, the desired persistence of antimicrobial action on the skin, and the level of risk of infection (such as if you know you are working with a patient with a high pathogenic bacteria load).3,4
For routine dental examinations and nonsurgical procedures, hand washing and hand antisepsis can be achieved by using plain soap or antibacterial soap and water. Mechanical friction and rinsing thoroughly are critical to effective hand washing. The mechanical action lifts dirt and microbes from the skin surface so they can be rinsed away. If hands are not visibly soiled, using an alcohol-based hand rub is sufficient.3,4
Although gloves must be worn when performing surgery, surgical hand antisepsis is still necessary. This removes transient flora and at least temporarily reduces the population of resident flora to prevent transmitting pathogenic organisms into an open wound, in the event that gloves become torn or punctured. Agents for surgical hand antisepsis should significantly reduce a broad spectrum of microorganisms on the skin, be non-irritating, and fast acting.3,4 It should also have a persistent effect, meaning that it has long-lasting antimicrobial activity that inhibits the survival of microorganisms after the product is applied, because microorganisms can proliferate in the moist environment under gloves. 3,4
Alcohol hand rubs are fast-acting germicides, but to achieve persistent activity, they should include antiseptics such as chlorhexidine, octenidine, triclosan, or quaternary ammonium compounds.3,4
Several factors can influence the effectiveness of hand washing and hand antisepsis, including the duration and technique of washing or scrubbing, the condition of the hands (such as irritated or healthy), and techniques used for drying or gloving.3,4
Antiseptic Agents for Hand Hygiene
Plain (non-antimicrobial) Soap
Soaps are detergent-based products that contain esterified acids and sodium or potassium hydroxide. Their detergent properties assist in the removal of dirt, soil, and other organic substances from hands. They have minimal antimicrobial activity; however, hand washing as recommended with plain soap can remove transient bacteria. Hand washing with plain soap and water for 15 seconds reduces bacterial counts on the skin by 0.6 to 1.1 log10; doubling the time to 30 seconds reduces bacterial counts by 1.8 to 2.8 log10.11 Plain soap may be associated with skin irritation and dryness, and they have been known to become contaminated with pathogenic bacteria.3,4
In the United States, these products are available in low viscosity rinses, gels, and foams, and they contain isopropanol or ethanol, or a combination of the two.3,4 They have antimicrobial activity due to their ability to denature proteins.8 A 60% to 95% alcohol solution has been found to be the most effective, with in vivo studies showing germicidal activity against bacteria, including multidrug-resistant forms like MRSA and VRE, Mycobacterium tuberculosis, and fungi. They have also shown the ability to reduce infectivity of nonenveloped viruses, such as rotavirus and rhinovirus, enterovirus, and hepatitis A. Certain enveloped viruses, such as herpes simplex, influenza, and human immunodeficiency virus (HIV), have been found to be susceptible to alcohols in vitro.3,4,8,12,13
Alcohol-based products are fast acting, but have very little persistent activity; regrowth of bacteria does occur after use of an alcohol-based hand rub. Persistent activity can be conferred by the addition of chlorhexidine, triclosan, quaternary ammonium compounds, or octenidine.3,4,8 Alcohol-based products have been found to be more effective at reducing the number of multidrug-resistant pathogens on the hands of healthcare workers and reducing the odds of their transmission than hand washing with soap and water.14 They have also been found to be more cost-effective.15 Alcohol-based rubs may be associated with skin irritation and dryness.5
Available in the form called chlorhexidine gluconate (CG), it is a water-soluble antimicrobial that attaches to, and eventually disrupts, the cytoplasmic membranes of microorganisms.8 Its antimicrobial activity is slower than that of alcohols, but it has substantial persistent activity, making it a common addition to alcohol-based rubs.3,4,8 The addition of even low concentrations of CG (0.5% to 1%) results in greater residual activity than alcohol alone. CG is also added to other types of hand hygiene preparations with concentrations of up to 4%. At concentrations over 1%, care must be taken to avoid contact with eyes because it can cause conjunctivitis and severe corneal damage; frequent use of a product with a concentration of 4% CG is linked to dermatitis.3,4,8
A more detailed review and a comprehensive list of antiseptic agents can be found in the 2002 CDC Guideline for Hand Hygiene in Health-Care Settings and the 2003 CDC Guideline for Infection Control in Dental Health-Care Settings. The list includes hexachlorophene, chloroxylenol, iodine and iodophores, quaternary ammonium compounds, and triclosan.
Skin Irritation Associated with Hand Hygiene Products
Frequent and repeated use of hand hygiene products can cause occupationally related irritant contact dermatitis, a nonallergic reaction that manifests as dry, itchy, irritated areas on the skin that was in contact with the product.3,4,16 Detergents, fragrances, preservatives, alcohols, and other chemicals, such as chlorhexidine, can cause this type of irritation, which disrupts the skin barrier and renders it more susceptible to colonization by pathogenic bacteria.3,4,16 Adding emollients to hand hygiene products has been found to reduce irritation and dryness, and taking measures to replenish skin moisture, such as applying a rich cream overnight, can help restore dermal integrity. This is important because healthy, unbroken skin is the primary defense against infection and transmission of pathogens.3,4
Other Aspects of Hand Hygiene
These prevent contamination of the hands when touching the patient, or touching substrates that are pathogenic-laden, such as mucous membranes, blood, saliva, and dental plaque. They also reduce the odds that microorganisms on the hands of the dental healthcare professional will be transmitted to the patient. However, gloves do not provide complete protection because tiny tears or defects can allow the contamination of the hands. Hands can also get contaminated during glove removal. This is why wearing gloves does not eliminate the need for hand washing, which must be done immediately before donning gloves, and immediately after taking them off.3,4
There are other considerations when it comes to maximizing the effectiveness of gloves as a protective measure. Hands must be dried thoroughly before putting gloves on, because the moisture under the gloves can encourage rapid bacterial growth. Gloves must be changed between patients, and when torn or punctured. The use of petroleum-based lotions or creams compromises the integrity of gloves, so these products should not be used in a dental care setting.3,4
The powder used inside some brands of gloves can be a source of irritant contact dermatitis, so additional moisturizing and soothing measures may be needed to keep the skin healthy. Although it is uncommon, some people may suffer allergic reactions to latex gloves, which includes cutaneous, respiratory, and conjunctival symptoms in response to latex protein.3,4
Skin underneath rings is more heavily colonized by flora than skin on the hand that is not covered by rings. Rings themselves harbor bacteria: Studies of healthcare workers have shown that rings were the only substantial risk factor for carriage of Staphylococcus aureus, and the concentration of microorganisms on the hand correlated with the number of rings worn.17 The current CDC recommendation is to remove jewelry and wash hands with soap and water for at least 15 seconds before donning gloves. However, a more recent study found that more time—up to 25 seconds—was needed to adequately remove bacteria from skin that is usually covered by a ring. In addition, the microbes were more difficult to remove from the palm compared to the back of the hand, indicating that more scrubbing on the palm side of the ring finger is necessary.18
Fingernails and Artificial Nails
The majority of flora on the hands are found under and around the fingernails, which is why keeping nails short and cleaning them often is key to preventing the transmission of microorganisms. Keeping nails short also prevents glove tears. Also of interest is that while painted nails pose no concern, chipped nail polish harbors more bacteria. Although there are presently no recommendations against wearing them, artificial nails have been found to harbor more pathogenic bacteria when compared to natural nails even after hand washing; and artificial nails, as well as artificial nail tips, have been implicated in several outbreaks of fungal and bacterial infections in hospital settings.3,4
Mobile phones are becoming more ubiquitous in the dental office, but many dental healthcare professionals may be underestimating its potential as a source of bacteria. One study found that 18% of dental faculty and trainees used their phones while attending to patients, nearly 64% used their phones to check the time, and 64% reported never cleaning their phones. When their phones were cultured for microorganisms, 34% grew pathogenic bacteria. With alcohol decontamination, bacterial load was reduced by 87%.19 When it comes to minimizing the spread of infection in the dental healthcare setting, it appears necessary to consider mobile phones and other personal devices (for example, iPods) as surfaces that can harbor potentially harmful bacteria that can contaminate the hands.
Hand hygiene in the dental healthcare setting is a crucial, yet simple, disease-prevention measure. It substantially reduces potential pathogens on the hands, and is considered the most important method of reducing the risk of transmitting organisms to patients or of acquiring infections from patients.
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