Hand Hygiene
Günter Kampf
TYPES OF HAND FLORA AND RELEVANCE FOR INFECTION CONTROLThe effects of antiseptics applied to intact skin varies depending on the location of the skin (eg, in moist or drier skin areas, or in skin with a higher or lower density of sebaceous glands). In this review, the focus is on the hands. Three types of hand flora are distinguished since 1938: the resident flora, the transient flora, and the infectious flora.1,2
Resident Hand Flora
Inhabitants of the resident hand flora are typically found on the epidermal surface and especially under the superficial cells of the stratum corneum.3 The species are not considered to be pathogens on intact skin, but in sterile body cavities or on damaged skin, they may cause infections.4 The resident skin flora protects the skin from the adhesion of transient pathogenic species (colonization resistance) by exhibiting a microbial antagonism and competition in the dermal ecosystem.5
Staphylococcus epidermidis can almost always be found on hands.6,7,8 The rate of oxacillin resistance can be as high as 64.3%.6 Staphylococcus hominis, Staphylococcus warneri, and other coagulase-negative staphylococci9,10 as well as propionibacteria, corynebacteria, dermabacteria, and micrococci can also be found as permanent skin inhabitants.11,12 Malassezia (previously known as Pityrosporum) has been described as a fungus to reside on human skin.13 Viruses, however, are not considered permanent skin inhabitants.
The total colony count of resident flora on both hands has been described to be between 3.9 × 104 and 4.6 × 106 in health care workers.1,14,15,16 The highest density with approximately 60 000 CFUs/cm2 is found in the subungual spaces; other areas on the hand have lower counts with 90 to 850 CFUs/cm2.17
Transient Hand Flora
The transient flora describes microorganisms which can only be transiently found on the skin (eg, after contact with patients, animals, or food). Typical transient species on health care workers hands are summarized in Table 42.1. Overall, gram-negative bacteria species are less frequently found on health care workers hands. The density of bacterial transient hand flora increases with the duration of patient care on average by 6 CFUs/min.19
Infectious Flora
In addition, the infectious flora can be described as species such as Staphylococcus aureus or β-hemolytic streptococci, which are frequently isolated from skin infections, such as from abscesses, whitlows, paronychia, or infected eczema.20
Relevance for Infection Control
Hand hygiene is considered to be a key element for prevention of health care-associated infections. In one particular study, it was shown that increasing the compliance in hand hygiene from 48% to 66% over 4 years reduced the rate of health care-associated infection from 16.9% to 9.9%.21 As a consequence, indications for hand hygiene were harmonized, initially called “five moments of hand hygiene.” These included recommendations of hand hygiene before touching a patient, before clean and aseptic procedures, after contact with body fluids, after touching a patient, and after touching patient surroundings.22 Another consequence
was to establish different types of multimodal campaigns to improve compliance among health care workers.23
was to establish different types of multimodal campaigns to improve compliance among health care workers.23
TABLE 42.1 Frequency of nosocomial pathogens detected on health care workers’ hands (range)a | ||||||||||||||||||||||||||||||||||||
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The World Health Organization (WHO) alliance for patient safety has started the first global campaign on patient safety on October 13, 2005 (“clean care is safer care”).24 Promoting hand hygiene has been considered a key element in the campaign.25 The goal is to implement national strategies for improving hand hygiene in all countries.26 In 2009, the first global guideline on hand hygiene was published by the WHO.27 As of January 2018, 139 member states have formally committed themselves to reduce the rate of nosocomial infections in their country, to report their results, and to learn from each other. In 2015, two alcohol-based hand rubs were added to the WHO list of essential medicines: one based on 80% (vol/vol) ethanol and one based on 75% (vol/vol) iso-propanol.28 The increase of antimicrobial, specifically antibiotic resistance worldwide, makes targeted hand hygiene even more important to prevent transmission in health care facilities.29
TABLE 42.2 Types of soils and proposals for suitable cleaning agentsa | ||||||||||||||||||||||||
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SIMPLE HAND WASHOriginally, the washing of the hands had a primarily symbolic meaning in rituals of the great world religions (eg, before a prayer). Hands were also washed when they had to be cleaned, although often to remove gross materials from the hands rather than to reduce the impact of microbial transmission (eg, after a meal because cutlery to eat was not always available in antiquity). In the Middle Ages, the washing of hands became more and more important for infection control and prevention.30 Today, simple hand washing is still the method of choice for keeping hands clean at home and in other situations; however, in patient care, it should be an exception.
Definition
A simple hand wash describes a rinse-off procedure with water with the aim of cleaning hands. Plain liquid or bar soap may be used during washing, particularly in the removal of soils. Soaps used for a simple hand wash do not contain active, antimicrobial ingredients. That is why the effect is physical removal, both on the reduction of soil and on the reduction of microorganisms.
Typical Applications
A simple hand wash is usually carried out on visibly soiled hands with the aim of cleaning them. Four different types of soiling can be distinguished (Table 42.2). In health care, one can expect mainly a slight or medium grade of
contamination so that washing hands with water and soap should be sufficient.
contamination so that washing hands with water and soap should be sufficient.
TABLE 42.3 Mean log10 reduction of different bacterial spores by washing hands with plain soap and water | ||||||||||||||||||||||||||||||||||||||||
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Another reason is the proven or suspected contamination of hands with bacterial spores such as Clostridium difficile in health care settings or Bacillus anthracis in bioterrorism. Infections caused by C difficile are among the four most common types of health care-associated infections32 which were transmitted in the hospital in 70% of all cases.33 In 2001, letters were sent in the United States, contaminated with spores of B anthracis. A total of 22 anthrax infections were observed, 11 of them with pulmonary anthrax and 11 with dermal anthrax.34 Bacterial spores can be reduced by a simple hand wash by approximately 2 log10, irrespective of the duration of washing (Table 42.3). In case of suspected or proven contamination of the hands with C difficile, it is advisable to perform the hand wash after a hand disinfection because patients colonized with C difficile are co-colonized with vegetative bacteria pathogens, such as 55.8% with vancomycin-resistant enterococci (VRE)40 and in 31% with extended spectrum β-lactamase (ESBL) enterobacteriaceae.41 Patients with a C difficile infection carry ESBL enterobacteriaceae in 62% of cases.41
Bar soap has no place in health care42 because it is basically always contaminated and may be a reservoir for pathogens such as Pseudomonas aeruginosa or Klebsiella pneumoniae.43 Liquid soap is first choice, although it often does not show an increase in the overall microbial reduction on clean hands in a 20-second hand wash (0.3 log10 difference), as shown with Enterobacter aerogenes.44 On hands soiled with meat, however, the hand wash with liquid soap was more effective by 1.1 log10.44 Liquid soaps may, themselves, be occasionally contaminated due to poor preservation activity (see chapter 6) (eg, with Pseudomonas cepacia,45,46 P aeruginosa,46,47,48,49 Escherichia coli,47 E aerogenes,47 K pneumoniae,46,47,50 Enterobacter cloacae,46,47 Serratia marcescens,47,51 Klebsiella oxytoca,47 Citrobacter species,50 Pseudomonas putidas,46 or Pseudomonas luteola46). In case of a soap dispenser contamination, biofilm is likely to be found inside the dispenser design52 so that a simple rinse of the dispenser is not an effective way of decontamination.45
A procedure of hand washing was recommended by the WHO to be done using specific steps of hand movement, being first described in 197853 based on data with insufficient hand coverage.54,55 Recent data obtained with C difficile suggest that the effect on spore removal is significantly better using a structured compared to an unstructured hand washing technique (1.7 versus 1.3 log10 reduction).56 A similar finding was described in contact lenses washing studies. A multistep hand washing for 34 seconds transferred less lipids to the contact lenses compared to an 11-second unstructured hand washing.57 In clinical practice, however, the duration of a hand wash is typically between 7 and 10 seconds.58
The applied volume of soap in clinical practice is variable and has been described in a study of 47 nursing staff and 10 other persons to be between 0.4 and 9 mL per hand wash.59
The fastest drying of hands can be achieved with cotton or paper towels with 4% to 10% or water remaining on the hands after 10-second drying.60,61 Hot air dryers have actually worse drying effects60 and can even distribute microorganisms in the air within a radius of 1 m.62 Finally, air driers can irritate the skin and cause skin dryness, roughness, and redness over time.61
Test Methods and Efficacy Requirements
The effect is 2-fold, reduction of soil and microorganisms. There are currently no specific methods used to measure the reduction of soil or microorganisms for simple
hand washing, including no specific efficacy requirements (definition of a minimum to qualify as an effective soap). Nevertheless, some studies describe the effect of a simple hand wash on reducing microorganisms.
hand washing, including no specific efficacy requirements (definition of a minimum to qualify as an effective soap). Nevertheless, some studies describe the effect of a simple hand wash on reducing microorganisms.
TABLE 42.4 Mean log10 reduction of different bacterial species by washing hands with plain soap and water | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Efficacy on Resident Hand Flora
Efficacy on Transient Hand Flora
The effect on the transient bacterial flora is better (Table 42.4). A hand wash of 30 seconds or longer usually reduced transient bacteria by about 2 log10. A higher contamination resulted in a lower efficacy as shown with Acinetobacter baumannii (2.0 versus 3.8 log10)80 or methicillin-resistant S aureus (MRSA) (1.4 versus 1.9 log).87 Viruses can also be reduced by hand washing (Table 42.5), but log10 reductions with feline calicivirus (FCV) and rotavirus were quite low.
Side Effects
The overall dermal tolerance of hand washing is rather poor.97 An analysis of 1932 skin evaluations revealed that washing hands with soap and water is a risk for dry and irritated skin.98 Frequent hand washing (>10 times per day) is a relevant risk for irritated skin with a relative risk of 1.55.99 The composition of the soap can have a significant impact on the dermal tolerance and the cleaning efficacy.31,100 Reducing the frequency of hand washing and increasing the use of alcohol-based hand rubs can significantly reduce skin redness (21.7% versus 11.0%) and
itchiness (15.8% versus 7.1%) as shown on health care workers from seven intensive care units (ICUs).101 A direct comparison of hand washing or hand rubbing over 8 days among 52 nurses showed a significantly worse skin condition and a significantly higher degree of skin damage in the hand washing group.102
itchiness (15.8% versus 7.1%) as shown on health care workers from seven intensive care units (ICUs).101 A direct comparison of hand washing or hand rubbing over 8 days among 52 nurses showed a significantly worse skin condition and a significantly higher degree of skin damage in the hand washing group.102
TABLE 42.5 Mean log10 reduction of different viruses by washing hands with or without plain soap and water measured as reduction of viral infectivity in cell culture assays | ||||||||||||||||||||||||||||||||||||||||||||
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HYGIENIC HAND WASHWashing hands with an antiseptic agent was introduced in human medicine in 1847 when Ignaz Semmelweis performed hand washes with chlorinated lime in a basin.105 The first washing lotions contained two active ingredients such as chlorhexidine and cetrimide.106 Today, chlorhexidine or octenidine are commonly used. Many other microbicides have also been traditionally used in such hand washes. But, regular use of antimicrobial soaps in countries with low incomes did not show reduced infection rates compared to the use of plain soaps.107 Triclosan and 18 other substances that have been used are now banned by the US Food and Drug Administration (FDA) in 2016108 as an active ingredient in consumer antimicrobial soaps because of a lack of direct clinical benefit (ie, a reduction of infection), risks of toxic reactions including hormonal effects, environmental concerns, and the risk of triggering bacterial cross-resistance to antibiotics by sublethal concentrations.109
Definition
A hygienic hand wash (FDA: health care personnel hand wash) describes a rinse-off procedure with water with the aim of cleaning hands and to have an antimicrobial effect at the same time. Liquid soaps based on biocidal agents such as 4% chlorhexidine or 1% octenidine may be used during washing. The overall effect is 2-fold: a physical one removing soil and microorganisms and a chemical one killing bacteria and yeasts to some extent during the application.
Typical Applications
In patient care, there is rarely an indication to perform a hygienic hand wash because clean hands should be routinely treated with alcohol-based hand rubs when an indication for hand hygiene occurs. The WHO recommends that health care facilities using alcohol-based hand rubs should not provide health care workers antimicrobials soaps.110 Preparing or handling food, however, is a different scenario because hands may often be soiled and contaminated so that a combined procedure with cleaning the hands and having some antimicrobial activity can be valuable.
It is recommended by WHO to perform the hygienic hand wash with a six-step procedure.110 If the six-step procedure provides an additional benefit (eg, more reduction of soil, stronger antimicrobial efficacy) compared to other washing procedures is unknown. A 30-second application time is usually required to exhibit a bactericidal and yeasticidal activity. Transient flora such as E coli (EN 1499) or S marcescens (ASTM E1174) is usually reduced by 2 to 3 log10 steps within 30 to 60 seconds, depending on
the specific product tested. The efficacy is often reported to be remarkably lower compared to alcohol-based hand rubs (approximately 4-5 log10).
the specific product tested. The efficacy is often reported to be remarkably lower compared to alcohol-based hand rubs (approximately 4-5 log10).
Test Methods and Efficacy Requirements
In Europe, the spectrum of antimicrobial activity of products used in human medicine must include bactericidal activity according to EN 13727 and yeasticidal activity according to EN 13624.111 The same spectrum of antimicrobial activity is required in the United States, although the number of bacterial species to be investigated to determine bactericidal activity is much higher with at least 20 species compared to 4 species in EN 13727.112 In veterinary medicine, the products must be at least bactericidal according to EN 13727.111 Hygienic hand wash products used in food, industrial, domestic and institutional areas have in Europe no specific minimum spectrum of antimicrobial activity. Tests are available to demonstrate bactericidal (EN 1276) and yeasticidal (EN 1650) activity.111
In Europe, the in vivo efficacy of hygienic hand wash products is evaluated according to EN 1499 for all fields of application.113 In the United States, it was determined for many years according to the test method described in the Tentative Final Monograph for Healthcare Antiseptic Products published in 1994112 similar to ASTM E1174.114 In 2015, the FDA has proposed a new test method for hand scrub products with a single application and defined new efficacy requirements.115 The methods are summarized in Table 42.6. Although hygienic hand wash products have to show superiority compared to a negative control according to EN 1499 (relative requirement, similar to clinical trials), they are required to show at least a 2.5 log10 reduction according to the FDA proposed rules (absolute requirement).
Side Effects
The skin compatibility of antimicrobial soaps used for hygienic hand wash is often reported to be poor especially when used frequently. This is mainly explained by the types of detergents used in the formulation. In addition, adding chlorhexidine or octenidine to the product formulation can influence dermal tolerance and affect the irritation potential of a final formulation.97 The potential for allergic reactions is described below (side effects, surgical hand rubbing, page 871).
TABLE 42.6 Overview on critical test parameter of EN 1499, ASTM E1174, and the proposed FDA rules for antiseptic hand wash products | ||||||||||||||||||||||||||||||||||||||||||||
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HYGIENIC HAND DISINFECTIONThe term hygienic hand disinfection was introduced by Wilhelm Speck in 1905, who described procedures for hand decontamination with alcohol-based solutions so that neither the user nor the environment of canalization were contaminated during use (“hygienic”).116 In the 1960s, alcohol-based hand rubs containing emollients were offered for the first time in central Europe117 in order to reduce skin dryness when used frequently.118,119
Definition
Hygienic hand disinfection (FDA: health care personnel hand rub) describes a leave-on procedure with an alcoholbased hand rub, gel, or foam. It should be performed in the following clinical situations: before touching a patient, before clean and aseptic procedures, after contact with body fluids, after touching a patient, after touching patient surroundings, and after glove removal.22 The formulations are typically based on ethanol, iso-propanol, n-propanol, or a combination of these alcohols. The overall concentration of alcohol(s) is often between 60% and 95% with a trend to better antimicrobial efficacy with higher alcohol concentrations.120 The antimicrobial efficacy of lower alcohol concentrations may theoretically be increased by retarding the evaporation time of the alcohol (ie, by adding specific excipients to a formulation). But so far, published data indicate that alcohol-based gels or lotions tend to be often less effective compared to alcohol-based solutions. The WHO has described hand rubs-based ethanol at 80% (vol/vol) or iso-propanol at 75% (vol/vol) as essential medicines,28 although they are not found to meet European efficacy requirements when applied with 3 mL for 30 seconds.121
Typical Applications
Alcohol-based hand rubs are usually applied to clean and dry hands. During an application time of 30 seconds, the product is distributed all over both hands to ensure complete hand coverage. The WHO recommends to apply a specific rub-in technique with six steps similar to the one used for testing the efficacy according to EN 1500.122 In clinical practice, however, hand coverage is often incomplete. In a study with 546 students, 55.1% of hands were incompletely covered with even 7.1% incomplete coverage on the palmar side where complete coverage is easy to accomplish.123 Treatment gaps are typically found on the thumb and the index finger.124 The recommended six steps are rarely done in clinical practice. In South Korea, 2174 hand disinfections were observed. In only 7.4%, all six steps were done as recommended.125 Similar results were reported from Switzerland with 8.5% of 2480 hand disinfections being performed with all six steps.126 Alternatives such as the “responsible technique” (individual technique with feedback) yield better hand coverage.127 It is particularly important to cover the thumb and the finger tips (Figure 42.1). A good rub-in technique and professional experience are relevant factors that can have a significant impact on the efficacy of the hand disinfection.124 That is why education and feedback are important to optimize personal practices.129 The presence of soil may not significantly reduce the efficacy of certain alcoholbased hand rubs,130 depending on the level and type of soil, but overall, the soil will not be removed during a hand disinfection.
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