As part of an investigation by an independent, accredited laboratory, it was demonstrated that the hand disinfectants Sterillium® med, ethanol-based, and Sterillium® pure, propanol-based, fulfil the efficacy requirements for bactericidal efficacy of hygienic hand disinfection (test standard EN 1500) with a contact time of 15 seconds [1].
When hand hygiene in clinical practice is discussed, the focus is often on disinfecting hands at the right moment or indication. However, effective hand disinfection requires more than just the right situation, it also requires the correct application of an effective disinfectant.
This includes complete wetting of the hands during the specified contact time. This requires both a good rub-in technique and a sufficient amount of disinfectant to wet the hands completely and keep them wet for the entire contact time.Standardised test methods are used to determine the combination of amount and contact time at which a disinfectant is effective. To be suitable for hygienic hand disinfection, for example, a disinfectant must pass the EN 1500 test [2]. There can be major differences between disinfectants even for professional use. For example, there are disinfectants that achieve bactericidal hygienic hand disinfection according to EN 1500 with 3 mL in 30 seconds, while others require 2x 3 mL in 30 seconds or even longer [3].
The test standard EN 1500:2013 [2] is the basis for the claim bactericidal hygienic hand disinfection. In practice, the test standard is carried out twice with 18-22 volunteers, once with a reference and once with a test product. To prepare, the test subjects wash their hands before they are contaminated with the test organism E. coli (Fig. 1 part 1). The fingers are then sampled to determine the so-called prevalue, which indicates how many bacteria are on the hands before disinfection (Fig. 1 part 2). Disinfection is then carried out by either using the reference method with 2x 3 mL 60% isopropanol for 2x 30 seconds or using the test product according to the manufacturer's instructions (Fig. 1 part 3). In both cases, hand disinfection is performed according to a standardized rub-in method. The hands are then sampled again to determine the so-called postvalue, i.e. the amount of bacteria still on the hands after disinfection (Fig. 1 part 4). The pre- and post-values can be used to calculate how effectively the test product and the reference method have inactivated the bacteria (Fig. 1 part 5). Finally, the effectiveness of the test product and the reference is compared. To pass EN 1500, the test product must not be statistically inferior to the reference. The reference thus determines the efficacy requirements for a disinfectant for hygienic hand disinfection.
In principle, the correct rub-in times can be found in the manufacturer's instructions. These are based on the relevant test standard and product approval. Adhering to these instructions ensures that a disinfectant is sufficiently effective. In the hectic daily routine of clinical practice, a short rub-in time naturally facilitates the correct application of a disinfectant [4, 5]. However, the EN 1500 test standard [2] does not currently provide for product testing with a rub-in time of less than 30 seconds. The minimum contact time declared on disinfectants for hygienic hand disinfection is therefore 30 seconds.
However, research has also investigated rub-in times of less than 30 seconds and their effect in practice [5-8]. There are both studies that support and studies that oppose shortening the rub-in time. On the one hand it has been shown that the inactivation of microorganisms on the hands after 10 to 20 seconds is comparable to 30 seconds [6] and that the frequency of disinfection increases with a shorter contact time [5]. On the other hand, it is questioned whether shorter rub-in times are sufficient to completely wet the hands [7]. Moreover, studies with shorter rub-in times have been criticised because the reference procedure, i.e. the minimum requirements, was often different in these studies [8].
As very few users adhere to 30 seconds in practice, acceptable times appear to be 15 to 20 seconds [9], shortening the rub-in time remains a current topic. More and more guidelines, professional associations and experts are now in favour of reducing the rub-in time to 15 seconds, including the SHEA recommendation “Strategies to prevent healthcare-associated infections through hand hygiene” [10] and the German Clean Hands campaign (Aktion Saubere Hände) [11]. In addition, the WHO rub-in technique for alcohol-based hand hygiene products is 20-30 seconds, and the Society of Healthcare Epidemiology of America (SHEA) recommends a minimum rub-in time of 15 seconds for alcohol-based products. The main hope here is that a lower hurdle will lead to more frequent disinfection. On the other hand, however, there are also professional associations and experts who are critical of shortening the contact time. As only a few employees already adhere to the 30 seconds, there are fears that shortening the contact time will lead to even less time being spent on disinfection.
Ultimately everyone agrees that no compromises can be made when it comes to patient safety. In addition to EN 1500, other efficacy tests must also be met in accordance with existing requirements and occurring pathogens. It is essential that the exposure times to achieve the required spectra of activity are met.
To test the effects and suitability of a shorter contact time, the ethanolic hand disinfectant Sterillium® med and the propanolic hand disinfectant Sterillium® pure were tested with a contact time of 15 seconds according to EN 1500[1] (Fig. 2). In order to maintain the quality requirements of the test standard, the reference procedure remained unchanged. Both disinfectants were tested with 5 mL each and the rub-in technique according to EN 1500 as well as 3 mL and the ‘responsible rub-in technique’. The only requirement for the ‘responsible rub-in technique’ is that the hands must be completely wetted within the specified time, especially fingers and thumbs. This is more in line with intuitive application in clinical practice. The effectiveness of the Sterillium® products was subsequently compared with the reference.
Both Sterillium® med and Sterillium® pure were shown to be non-inferior to the unmodified reference in both rub-in techniques. [1].
Thus, both hand disinfectants fulfil the requirements for bactericidal hygienic hand disinfection according to EN 1500 after just 15 seconds (Fig. 3).
The study shows that Sterillium® med and Sterillium® pure can achieve the shorter rub-in times requested by users in terms of bactericidal hygienic hand disinfection according to EN 1500. Recent studies have shown that especially trained personnel can achieve sufficient wetting of the hands within 15 seconds [12, 13]. These studies contribute to remove current barriers in hand disinfection and facilitate the way to a more user-friendly application of hand disinfectants.
In the future, further research should show the effects on clinical practice and whether the requirements according to EN 17430 on virucidal hygienic hand disinfection can also be achieved in 15 seconds. Whether you have 15 seconds or 30 seconds to achieve bactericidal efficacy, Sterillium® med and Sterillium® pure will keep you on the safe side.
[1] Mönch et al. (2024) Alcohol-based hand rubs can fulfil the efficacy requirements of EN 1500 in 15 seconds. GMS Hyg Infect Control 19:1–6.
[2] DIN EN 1500-2013: Chemical disinfectants and antiseptics - Hygienic handrub - Test method and requirements (phase 2/step 2). 2013.
[3] VAH disinfectant list https://vah-online.de/de/vah-liste (accessed 30.07.2024)
[4] Harnoss JC et al. (2020) Hand antisepsis without decreasing efficacy by shortening the rub-in time of alcohol-based handrubs to 15 seconds. J Hosp Infect 104: 419–424.
[5] Kramer A et al. (2017) Shortening the Application Time of Alcohol-Based Hand Rubs to 15 Seconds May Improve the Frequency of Hand Antisepsis Actions in a Neonatal Intensive Care Unit. Infect Control Hosp Epidemiol 38: 1430–1434.
[6] Pires D et al. (2017) Hand Hygiene With Alcohol-Based Hand Rub: How Long Is Long Enough? Infect Control Hosp Epidemiol 38: 547–552.
[7] Kampf G et al. (2008) Influence of rub-in technique on required application time and hand coverage in hygienic hand disinfection. BMC Infectious Diseaes 8: 149.
[8] Eggerstedt S et al. (2018) Alcohol-based hand rubs must meet the requirements of EN 1500. Infect Control Hosp Epidemol. 39(8): 1018.
[9] Kenters N et al. (2020) Product dose considerations for real-world hand sanitiser efficacy. Am J Infect Control 48: 503–506.
[10] Glowicz JB et al. (2023) SHEA/IDSA/APIC Practice Recommendation: Strategies to prevent healthcare-associated infections through hand hygiene: 2022 Update. Infect Control Hosp Epidemiol 44: 355–376.
[11]Positionspapier „Einwirkzeit von Händedesinfektionsmittel“ der Aktion Saubere Hände https://www.aktion-sauberehaende.de/fileadmin/ash/user_upload/pdf/Positionspapiere/ASH_Positionspapier_15_Sekunden_01072020.pdf(accessed 30.07.2024).
[12] Paula H et al. (2018). Wettability of hands during 15-second and 30-second handrub time intervals: A prospective, randomized crossover study. Am J Infect Control 46:1032–1035.
[13] Pires D et al. (2017). Hand Hygiene With Alcohol-Based Hand Rub: How Long Is Long Enough? Infect Control Hosp Epidemiol 38:547–552.
Use disinfectants safely. Always read the label and product information before use.
