Inter-laboratory reproducibility of the hand disinfection reference procedure of EN 1500

Recent tests carried out using EN 1500 have suggested that most alcohol-based hand gels are significantly less effective than the reference alcohol [2-propanol, 60% (v/v)] whereas liquid alcohol-based hand rubs are not. However concerns about the accuracy and reproducibility of the test have been raised. We therefore analysed 41 experiments performed in four different laboratories using EN 1500 hand disinfection procedures with the reference alcohol, to analyse inter-laboratory reproducibility of the test. The mean reduction factors (difference of the log(10) of the pre-value and the post-value) from the four laboratories did not reveal a significant difference (P=0.059; analysis of variance), although the difference of the mean pre and post-values was highly significant (P<0.001). EN 1500 is a reproducible test method which leads to valid data.     

Hand disinfection according to the European Standard EN 1500 (hygienic handrub): a study with gram-negative and gram-positive test organisms.

It was the aim of this study to compare the efficacy of alcohol-based hand disinfectants according to European Standard EN 1500 (hygienic handrub), using the routine test organism Escherichia coli and, additionally, Micrococcus luteus as a surrogate for Gram-positive pathogens. One ethanol-based hand disinfectant (product A) and one propanol-based hand disinfectant (product B) were used in all experiments. Product B (propanol-based) was significantly more effective against both test organisms than product A (ethanol-based) in quantitative suspension tests but not in tests simulating practical conditions. In the experiments according to EN 1500 germ reduction rates obtained with the ethanol-containing formulation A were identical for E. coli and M. luteus. Product B was slightly, but not significantly more effective against M. luteus. To conclude, using E. coli as the test organism for evaluating the antibacterial efficacy of alcoholic hand disinfectants under practical conditions even appears to be sufficient to permit the drawing of conclusions for Gram-positive pathogens. However, more alcohol-based hand disinfectants should be tested in further studies to verify the results obtained.     

Efficacy of alcohol-based gels compared with simple hand wash and hygienic hand disinfection

A recent research letter on the limited efficacy of alcohol-based hand gels has alerted the global infection control community and raised the question of the true significance of data obtained according to EN 1500. It has been described that a 1 min simple hand wash reduces artificial contamination of hands by a log(10) reduction factor of 2.8 and a 1 min reference hand disinfection with 2-propanol (60%, v/v) by a factor of 4.6 steps. The EN 1500 gel data show that the 30 s efficacy of most gels is closer to a simple hand wash than to the reference hand disinfection. The 30 s efficacy of most alcohol-based liquid products and one gel, however, is almost identical to the reference hand disinfection. In many European countries alcohol-based liquid products have been established as a standard practice in hygienic hand disinfection for decades. Replacement of these products with most available gels would be a step backward in terms of efficacy and has still to be seen critically from the efficacy point of view.     

Dermatological aspects of a successful introduction and continuation of alcohol-based hand rubs for hygienic hand disinfection

With the new Centers for Disease Control and Prevention (CDC) guideline on hand hygiene, hospitals often introduce alcohol-based hand rubs for hand disinfection. Healthcare workers, however, may reject the new products because of skin irritation or other skin-related problems, which they experience after years of handwashing. In order to facilitate a successful introduction and continued use of alcohol-based hand rubs in hospitals, we have reviewed and summarized the major studies on the topic. Occupational hand dermatitis may occur in up to 30% of healthcare workers. It is mainly described as an irritant contact dermatitis caused by detergents. The diagnosis is usually clinical. Allergic reactions are very rare. After using an alcohol-based hand rub for the first time, healthcare workers may have a burning skin sensation that can be explained by pre-irritated skin. In this case the skin barrier has usually been impaired by frequent handwashing or occlusive gloves. This may result in a vicious circle whereby the healthcare worker increases the frequency of handwashing and reduces the frequency of hand disinfection. Prevention of irritant contact dermatitis is possible by selection of a low-irritating hand rub, which contains emollients, the correct use of the hand rub and a clear guideline when to disinfect and wash hands in the clinical setting. Common mistakes in the use of alcohol-based hand rubs are application to pre-irritated skin and washing hands before hand disinfection, which is, in general, not necessary, or after hand disinfection, which results in washing off the emollients. Clear preparation and guidance of healthcare workers before the introduction of alcohol-based hand rubs can help to enhance compliance in hand hygiene. The switch from handwash to alcohol-based hand rub will improve healthcare workers skin if mistakes are avoided and hand rinses are used correctly.     

Clinical double-blind trial on the dermal tolerance and user acceptability of six alcohol-based hand disinfectants for hygienic hand disinfection

Six commercially available alcohol-based hand rubs [AHD 2000, Desderman, Mucasept A, Manorapid (Poly-Alkohol, Spitacid, and Sterillium] were investigated in a clinical double-blind trial involving 10 participants who had no previous experience of using hand rubs (Group 1), and seven who had substantial professional experience of using hand rubs (Group 2; virology laboratory staff). Group 1 was studied for one week with 20 applications on day 1 and then five applications per day for six days. Transepidermal water loss, dermal water content and superficial sebum content of the skin were measured before and after the seven-day application of the products, as well as user acceptability (self-assessment of smell, speed of drying, emolliant effect, skin dryness). Group 2 used each preparation twice for two weeks in a random sequence, and carried out self assessment at the end of each fortnight. Transepidermal water loss (mean baseline: 18.7 g/m(2)h), dermal water content (mean baseline dorsum: 75.6) and superficial sebum content (mean baseline dorsum: 4.8 microg/cm(2)) did not change significantly. In both groups assessments of the smell and the speed of drying did not reveal any significant differences between the six products. Sterillium had the best emollient effect of all products (P<0.05; Wilcoxon test and Mann-Whitney-U test) and was significantly better than Desderman, AHD 2000, and Mucasept A, causing less skin dryness after seven days use in Group 1 (P<0.05; Mann-Whitney-U test). Manorapid caused significantly less dryness than Spitacid, AHD 2000, and Mucasept A in Group 2 after the first use, but no significant difference was observed after the second use. Thus alcohol-based hand rubs that contain emolliants, irrespective of the type of alcohol (n-propanol, iso-propanol or ethanol), are well tolerated and do not dry out or irritate the skin. Personal assessments showed significant differences for the emolliant effect and the extent of dryness. Both factors are very important, as user acceptability has an impact on compliance. Sterillium is the only hand disinfectant containing mecetronium etilsulphate which has been shown to have an emolliant effect. Future research should focus on user acceptability in order to improve compliance.     

两步法与六步法卫生手消毒的效果比较:一项随机对照交叉试验

 目的 探讨简化版两步法卫生手消毒与《WHO医疗机构手卫生指南》推荐的六步法卫生手消毒对医务人员手部自然菌的去除效果有无差异。方法 采用随机对照交叉试验方法对某三级甲等综合性医院的32名临床医护人员进行随机分组,试验组采用两步法,对照组采用六步法,前后两个阶段相互交叉进行试验,间隔一天洗脱期,比较卫生手消毒前后两组医务人员手部自然菌的平均杀灭对数值。结果 试验组与对照组医务人员卫生手消毒后的平均杀灭对数值均>1,消毒效果均合格,两组医务人员卫生手消毒后菌落数下降量均有统计学意义（均P<0.001）;比较两种卫生手消毒方法对细菌的平均杀灭对数值,差异无统计学意义（P=0.973）。结论 两步法卫生手消毒与六步法卫生手消毒效果一致,且两步法耗时更短,效率更高,值得临床推广。     

Test models for hygienic handrub and hygienic handwash: the effects of two different contamination and sampling techniques.

Two methods for artificial contamination of hands and two sampling techniques to recover the test organisms were compared for their effects on the results of two post-contamination hand treatments: a handrub with two portions of 3 ml of 2-propanol 60% v/v for 1 min, and a handwash with liquid soap 20% w/v for 1 min followed by a 15 s rinse. The two contamination methods involved a short immersion of the hands (up to the middle of the mid-hand) in a suspension of the test organism followed by either air-drying (3 min) or drying by rubbing the hands' vigorously against each other (3 min) in a standardized way. The two sampling techniques consisted of rubbing the fingertips in either 10 ml trypticase soy broth (TSB) against the bottom of a Petri dish; or 100 ml TSB against glass beads contained in a bowl. Sixteen volunteers were randomly allotted to four blocks of four. They carried out the four possible combinations of two treatments and two contamination methods in a series of four tests arranged in a Latin-square design. In addition, the two sampling techniques were compared with each other concurrently by sampling of the right and left hand each with a different one of the two techniques. The alcoholic handrub reduced the release of test organisms significantly (2P less than 0.005) more effectively, by 1.1-1.3 x log10, than did the handwash with liquid soap, regardless of the contamination or sampling method. Whereas the two recovery techniques yielded virtually identical results in corresponding situations, the method of artificial contamination affected the mean reduction factors, strongly.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparison of triclosan and chlorhexidine preparations with 60 per cent isopropyl alcohol for hygienic hand disinfection

Four detergent preparations containing triclosan; two alcoholic products, containing triclosan and chlorhexidine respectively, and a detergent preparation containing chlorhexidine were compared with 60 per cent isopropyl alcohol following a single hand wash using Escherichia coli as the test organism. In vitro tests indicated that all had a high activity against hospital pathogens. The triclosan-containing preparations exhibited a significant pathogens. The triclosan-containing preparations exhibited a significant residual activity. Experiments in volunteers showed that 0.5 per cent alcoholic triclosan was significantly more effective than all other preparations tested. All the detergent preparations had an effect similar to that of 60 per cent isopropyl alcohol. None of the seven products evaluated was significantly less bactericidal than 60 per cent isopropyl alcohol.     

A laboratory model for testing agents for hygienic hand disinfection: handwashing and chlorhexidine for the removal of klebsiella

A model for the laboratory assessment of hygienic hand disinfection is described which closely reproduces handwashing in a ward setting. The model uses a clinically relevant test organism and takes into account the natural antibacterial action of the skin. It also provides a means of measuring any residual antibacterial action after hand disinfection. Using an epidemic multiply-resistant strain of Klebsiella aerogenes K21, 0.5% chlorhexidine in iso-propyl alcohol yielded sterile post-disinfection finger washings more often than 4% chlorhexidine digluconate. Both preparations were more effective than soap and water, and with each residual action was demonstrable. The model is applicable to the laboratory evaluation of hygienic hand procedures and for agents of potential use in defined clinical settings.     

Comparison of two test methods for the determination of sufficient antimicrobial activity of three commonly used alcohol-based hand rubs for hygienic hand disinfection

In Europe, the antimicrobial efficacy of alcohol-based hand rubs is determined with a quantitative suspension test (prEN 12054) and a test under practical conditions (EN 1500). Another test method has recently been published by the German Society for Hygiene and Microbiology (DGHM) with four differences to the European system in the in vitro tests: additional qualitative suspension tests with product dilutions to the ineffective range; a selection of the most resistant Gram-negative test strains in the qualitative suspension test, which should be used adjacent to Pseudomonas aeruginosa in the quantitative suspension test; a high organic load in the quantitative suspension tests (0.3% albumin and 0.3% sheep erythrocytes); and an aqueous control in the quantitative suspension test. According to DGHM, the in vitro tests should be followed by EN 1500. We have determined the antimicrobial efficacy of three commonly used alcohol-based hand rubs according to both methods. prEN 12054 was carried out without organic load. The qualitative suspension tests (DGHM) were carried out with P. aeruginosa, Escherichia coli, Proteus mirabilis, Staphylococcus aureus, Enterococcus hirae and Candida albicans. The quantitative suspension test (DGHM) was carried out with product dilutions of 75%, 50% and 25%, and a high organic load using the following test organisms: P. aeruginosa, P. mirabilis (one product only), S. aureus, E. hirae and C. albicans. All these suspension tests were carried out in quadruplicate with each product and exposure time. EN 1500 was carried out with 3 mL of each product and an application time of 30 s. All three products achieved the required bactericidal activity of prEN 12054 and the new DGHM method within 30 s, and were equally effective with the reference hand disinfection of EN 1500 within 30 s. In our study, the DGHM test method did not provide additional information for hand rubs which exhibit their bactericidal efficacy with 3 mL within 30 s (EN 1500).     

Investigations into the efficacy of different procedures for surgical hand disinfection between consecutive operations.

In order to examine whether thorough surgical hand disinfection (handwashing plus hand disinfection) between consecutive operations is necessary, tests were carried out simulating normal clinical conditions. The tests were performed according to the guidelines for the evaluation of disinfection procedures of the German Society for Hygiene and Microbiology. Surgical hand disinfection was as follows: handwashing with soap without antimicrobial additives and subsequent 5-min disinfection with 60% n-propanol. This was followed by simulated operations of 30 or 120 min duration with a 30-min break between operations, during which half of the test group kept on the surgical gloves, while the other half removed them. The second surgical hand disinfection was done without prior handwashing by 50% of the test group. The disinfection time was reduced from 5 to 1 min by 50% of the test group. The results were evaluated by means of explorative data analysis and inductive statistical methods. Removing the surgical gloves during the interoperative break did not result in significantly higher numbers of colony forming units (cfu) compared with retaining the gloves. This was also the case after a subsequent handwashing. At the second surgical hand disinfection, after a simulated operation of 60 min duration (including break), there was no significant difference in the numbers of cfus between the test group who had washed their hands and those who had not. Reducing the disinfection time from 5 min to 1 min was not associated with a significant increase in the number of cfus. However, after a simulated operating time of 150 min (including the break), the second surgical hand disinfection with handwashing resulted in a significantly lower number of microorganisms than disinfection alone. In half the tests, the numbers of cfu were significantly lower when the test group disinfected their hands for 5 min rather than 1 min.     

Innovations in the environmental hygienic protection of soils (to the hygiene concept of soil cover protection)

The paper attracts the attention of sanitarians and scientific society to the soil hygiene issues that are, in the author's opinion, inadequately covered in both on-going studies and teaching. Based on long-term investigations, the author proposes approaches to forming the strategy for sanitary soil protection, including comprehensive waste control.     

Comparative review of the test design Tentative Final Monograph (TFM) and EN 12791 for surgical hand disinfectants

Preoperative antiseptic treatment of the hands of the surgical team is a standard procedure used worldwide in order to reduce the risk of surgical site infection. Two different types of antiseptics are available: alcohol-based hand rubs and antimicrobial liquid detergents ("soaps"). Standards have been developed to determine the antimicrobial efficacy of such preparations: the European norm EN 12971, finally issued in 2005, and the Tentative Final Monograph (TFM) for health care antiseptic products from 1994, which is the corresponding document in the USA. Although both methods use the reduction of resident hand flora as a quantitative parameter for antimicrobial efficacy, there are major differences concerning the test design. Whereas the European method is carried out following a randomized, reference-controlled crossover design, the US method can be characterized as a randomized, blinded parallel arm design. While both standards aim at immediate as well as sustained efficacy of the procedure, according to the EN the test product must not be significantly less effective than the reference procedure, whereas the TFM requires absolute reduction of > or = 1, > or = 2, and > or = 3 log10 per hand on days 1, 2, and 5, respectively. Results from various studies demonstrated that meeting the criteria defined by both standards may happen, but meeting the specifications of one standard does not necessarily mean that the same product will pass the requirements of the other. Missing accordance may be due to a number of considerable differences between both test methods. For a number of reasons the European method seems to be closer to clinical practice and to provide higher patient safety than the US method. However, available study data do neither allow for evaluation of the clinical impact of surgical hand disinfection as such nor of the effect of a particular product on postoperative wound infection rates.