a report by Mikael Zimmerman, DDS, PhD1 and Bengt Ternström2
1. Associate Professor and Assigned Reader, Clinical Oral Diagnosis, Karolinska Institute;
2. Training Director, Getinge Academy
Poor hand hygiene is the most common cause of transmission of infection. This applies not only to health- and medical-care settings, but also to childcare centers, schools, restaurants, elderly care centers, and at home. Hand-mediated transmission is a major contributing factor to the current infection threats to all patients, but among healthcare workers compliance with guidelines is poor. Studies have shown an association between workload, understaffing, and high patient load and an increased risk of
infections. The risk quadruples during periods of high stress—when staff are ‘pressed for time,’ hand hygiene is no longer given priority.
Hand cleaning and hand disinfection are two quite separate issues. The aim of hand cleaning is the removal of all visible dirt. Repeated cleaning of the skin with soap often causes irritation, which in turn leads to increased bacterial colonization of the skin and reduced effectiveness of disinfectants. Washing with soap should therefore be carried out only at the beginning of
the working day and thereafter only when the hands are visibly soiled. Hands—and particularly fingernails—harbor abundant dirt and microorganisms. During normal hand washing, a lot of the hand is ‘overlooked,’
e.g. the thumb of the right hand, the fingernails, and the fingertips.
Hand disinfection is intended to remove transient bacteria (those that are not part of the normal flora). For most hand disinfection purposes, alcoholbased hand-rubs are preferable to hand washing with soap and water. An alcohol-based hand-rub requires less time, acts faster, is less irritant to the skin of the hands, and contributes significantly to decreased infection rates. After every patient, the hands should be thoroughly disinfected using an alcohol-based disinfectant containing a rehydrating agent. For surgery, the agent of choice should have a residual effect.
Two Different Types of Microflora
The micro-organisms that occur on the skin of the hands and under the fingernails comprise the so-called ‘normal’ or ‘permanent’ skin flora as well as the so-called ‘transient’ skin flora. The permanent skin flora comprise micro-organisms that normally colonize the skin and under the fingernails. These bacteria are usually non-pathogenic and provide a certain protection against, for example, pathogenic bacteria. The permanent flora comprise mainly Gram-positive bacteria, e.g. Staphylococcus epidermidis. However, potential pathogens such as S. aureus can also colonize the skin and under the fingernails. The transient microflora of the skin can comprise many different types of micro-organism depending on what the hands may have touched, e.g. saliva or blood.
Part of the normal function of the skin is to provide a barrier protection against micro-organisms, wear, and chemical agents, and to regulate body temperature and protect the body from dehydration. The skin is a kind of permeable membrane between the body and the outside world. Under normal conditions, the thickness of the skin remains constant, and the rate of regeneration of skin cells—determined mainly by external influences (e.g. wear, chemical effect, etc.)—is directed by different cellular functions.
The fat (glycerol lipids) normally found in the skin forms an essential part of its barrier protection. In experiments in which the fat has been deliberately removed by acetone—which has a similar effect on the skin to cleaning agents—the barrier function is stabilized at around 50–60% effective within six hours, but a return to full function takes 5–6 days. This is one of the major reasons why washing with soap and water should be avoided and, in nursing settings, should be carried out only when the skin surface is
obviously soiled. The cleaning agent in soap dissolves fat and splits protein and will partly remove the protective layer of fat from the skin.
Hand washing with soap and water for 15 seconds reduces the transient bacterial flora by around 10-fold, and for 30 seconds by around 1,000-fold. However, washing with soap can also have the opposite effect—i.e. it can increase the bacterial flora on the hands—partly by disrupting the protective barrier of the skin of the hands (as described above) and partly because certain strains of bacteria can colonize and multiply in soap solutions. This applies particularly to pseudomonas and liquid soap in dispensers. In dispensers. In contrast, hand disinfection with alcohol-based disinfectant for 30 seconds
reduces the bacterial flora on the skin of the hand by 10,000-fold, and for 60 seconds by up to 100,000-fold—it is thus markedly more effective than washing with soap and water.
Although there is clear evidence that hand disinfection with alcohol-based disinfectant is superior to washing with soap and water, the latter is still the most common form of hand hygiene used by nursing personnel, who often have more faith in this procedure than in using only disinfectant on the hands. The occupational hazards of alcohols are negligible, but as alcohols have a dehydrating effect on the skin a rehydrating agent is added, usually between 1 and 3% glycerol.
Alcohols—Number One Recommendation
Alcohol-based disinfectants contain ethanol, isopropanol, n-propanol, or various combinations thereof. Ethanol at concentrations between 70 and 80% (volume percent) is most effective. At higher concentrations the denaturing potential of ethanol decreases and its disinfectant effect is less. Isopropanol has its optimal disinfectant effect at concentrations of approximately 60% (volume percent). A major disadvantage of isopropanols is that at high concentrations they evaporate readily at room temperature. Isopropanol irritates the mucous membranes, particularly the respiratory tract if inhaled. Solutions prepared for use as, for example, hand disinfectants therefore contain lower concentrations of isopropanol (around 40–46%); in order to attain a disinfectant effect corresponding to that of 60% isopropanol, ordinary ethanol, n-propanol, or other chemical disinfectants are added.
In general, alcohol is an effective disinfectant for vegetative bacteria, including methicillin-resistant S. aureus (MRSA), mycobacteria, fungi, and most viruses—i.e. encapsulated viruses such as herpes simplex virus, HIV, influenza virus, hepatitis B virus, and hepatitis C virus. However, alcohols are not as effective against naked viruses such as hepatitis A virus and polio virus. To compensate for this, a somewhat higher concentration of alcohol, or the addition of other disinfectant agents, is required. Alcohol has no effect against bacterial spores and protozoa (unicellular animals, e.g.amoeba). In general, ethanol has a better disinfectant effect than isopropanol on viruses. Alcohols have a rapid killing potential as hand disinfectants, but after disinfection there is a gradual regrowth of bacteria. The addition of quarternary ammonium compounds, chlorhexidine, or similar substances achieves a more lasting disinfectant effect and thus also a more certain result.
Apart from the concentration, other determinants of the effectiveness of hand disinfection are the duration of contact and the volume (amount) of disinfectant. Using small amounts—less than 1ml—offers no advantage over washing with soap and water. A good guide is that if the hands feel dry 10–15 seconds after rubbing in an alcohol-based disinfectant, the volume used was inadequate. It should take about 30 seconds for the hands to feel dry.
Surgical Protective Gloves
Gloves can prevent transmission of infection by reducing the degree of soiling of the hands. A fresh pair of unused gloves should be applied for every patient. Disinfectant on gloves markedly reduces the protective characteristics of the gloves. Gloves should not be used as a substitute for well-conducted antiseptic work routines; they are, however, an excellent complement.
Hand Hygiene with the Use of Gloves
The use of gloves actually increases the requirements for hand disinfection. There is very little air inside a well-fitting glove, and this can stimulate the growth of anaerobic bacterial flora. Anaerobic bacteria are often the most aggressive pathogenic bacteria. The moisture (perspiration from the hands inside the glove) provides an excellent substrate for the bacteria. This so-called ‘glovejuice’ is a potential risk to the patient, but is mainly a risk to the operator in terms of deterioration of the skin of the hands. Incorrect
handling of gloves is a frequent underlying cause of sensitivity reactions and development of allergies. In particular, this applies to washing hands with soap and water and then inserting them into a latex glove while still moist and bearing traces of retained soap. Once again, the use of a good alcoholbased disinfectant is preferred.
Latex, Vinyl, or Nitrile
Most of the gloves available on the market are made of latex, which is highly elastic and is therefore very resistant to puncture wounds. Vinyl is a synthetic alternative; however, it has poorer elasticity and less puncture resistance. There are also examination gloves made of nitrile—a synthetic material with very high puncture resistance.
The advantage of latex gloves is that they are made of a smooth, elastic material with good compressive and tensile strengths. The main disadvantage is the risk of latex allergy, which should not be underestimated. Latex allergy is a serious condition that in its worst form results in a number of fatalities annually. Latex gloves should therefore be selected with care and should have a documented low content of latex proteins and chemical residue. Incorrect use is a common underlying cause of sensitivity reactions and allergy development. Allergy to latex is a serious condition and it is important to treat all indications of suspected latex allergy very seriously. If staff notice problems associated with the use of latex gloves, allergy testing should be arranged as soon as possible. Thin gloves of polythene plastic may be used to advantage inside latex gloves to avoid direct contact of latex with the skin. The use of petroleum-based hand lotions or creams may adversely affect the integrity of latex gloves. After use of powdered gloves, certain alcohol-based hand-rubs may interact with residual powder on the hands, resulting in a gritty feeling.
A major advantage of vinyl gloves is that there is little or no risk of allergyor other sensitivity reaction. Disadvantages include poor resistance to physical load (tensile, compression, or puncture stress). In addition, the incineration of vinyl gloves releases an environmentally dangerous vapor. Nitrile is a synthetic latex material. The main advantage of this material is that no sensitivity or allergic reactions have been shown to the actual glove material, which contains no latex proteins. However, there may be allergenic
residual chemicals in the material.
The Most Important Procedure of All
Hand disinfection with an alcohol-based hand disinfectant should always be carried out before handling clean goods and after handling contaminated/used goods—this is one of the most important single procedures to prevent the spread of infectious diseases.
Recommended Literature:
Centers for Disease Control and Prevention (CDC) Guidelines for Hand Hygiene in Healthcare Settings: Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force, Morbidity and Mortality Weekly Report, 2002;51:RR16.
Mikael Zimmerman, DDS, PhD, is Associate Professor and Assigned Reader in Clinical Oral Diagnosis at the Karolinska
Institute. He has been awarded the Swedish Dental Academy Award and the Karolinska Institute Award for pedagogical efforts. Dr Zimmerman has published over 21 peer-reviewed papers, 50 abstracts, and three textbooks. E: mz@bzb.se

Bengt Ternström is Training Director of Getinge Academy. He has participated in implementing National Vocational
Qualifications for healthcare workers in China, UK, Sweden, and Romania. He is often engaged in national and international
seminars arranged by, for example, the International Federation of Infection Control (IFIC) and the World Forum for Hospital Sterile Supply (WHFSS). He obtained his MSc from the University of Stockholm, Sweden.