Christiane Ostermeyer

Efficacy of ethanol-based hand foams using clinically relevant amounts: a cross-over controlled study among healthy volunteers.

BackgroundFoams containing 62% ethanol are used for hand decontamination in many countries. A long drying time may reduce the compliance of healthcare workers in applying the recommended amount of foam. Therefore, we have investigated the correlation between the applied amount and drying time, and the bactericidal efficacy of ethanol foams.MethodsIn a first part of tests, four foams (Alcare plus, Avagard Foam, Bode test foam, Purell Instant Hand Sanitizer) containing 62% ethanol, which is commonly used in U.S. hospitals, were applied to 14 volunteers in a total of seven variations, to measure drying times. In a second part of tests, the efficacy of the established amount of foam for a 30 s application time of two foams (Alcare plus, Purell Instant Hand Sanitizer) and water was compared to the EN 1500 standard of 2 × 3 mL applications of 2-propanol 60% (v/v), on hands artificially contaminated with Escherichia coli. Each application used a cross-over design against the reference alcohol with 15 volunteers.ResultsThe mean weight of the applied foam varied between 1.78 and 3.09 g, and the mean duration to dryness was between 37 s and 103 s. The correlation between the amount of foam applied and time until hands felt dry was highly significant (p < 0.001; Pearsons correlation coefficient: 0.724; 95% confidence interval: 0.52-0.93). By linear correlation, 1.6 g gave an intercept of a 30 s application time. Application of 1.6 g of Purell Instant Hand Sanitizer (mean log10-reduction: 3.05 ± 0.45) and Alcare plus (3.58 ± 0.71) was significantly less effective than the reference disinfection (4.83 ± 0.89 and 4.60 ± 0.59, respectively; p < 0.001). Application of 1.6 g of water gave a mean log10-reduction of 2.39 ± 0.57.ConclusionsWhen using 62% ethanol foams, the time required for dryness often exceeds the recommended 30 s. Therefore, only a small volume is likely to be applied in clinical practice. Small amounts, however, failed to meet the efficacy requirements of EN 1500 and were only somewhat more effective than water.

Poorly processed reusable surface disinfection tissue dispensers may be a source of infection

BackgroundReusable surface disinfectant tissue dispensers are used in hospitals in many countries because they allow immediate access to pre-soaked tissues for targeted surface decontamination. On the other hand disinfectant solutions with some active ingredients may get contaminated and cause outbreaks. We determined the frequency of contaminated surface disinfectant solutions in reusable dispensers and the ability of isolates to multiply in different formulations.MethodsReusable tissue dispensers with different surface disinfectants were randomly collected from healthcare facilities. Solutions were investigated for bacterial contamination. The efficacy of two surface disinfectants was determined in suspension tests against two isolated species directly from a contaminated solution or after 5 passages without selection pressure in triplicate. Freshly prepared use solutions were contaminated to determine survival of isolates.Results66 dispensers containing disinfectant solutions with surface-active ingredients were collected in 15 healthcare facilities. 28 dispensers from nine healthcare facilities were contaminated with approximately 107 cells per mL of Achromobacter species 3 (9 hospitals), Achromobacter xylosoxidans or Serratia marcescens (1 hospital each). In none of the hospitals dispenser processing had been adequately performed. Isolates regained susceptibility to the disinfectants after five passages without selection pressure but were still able to multiply in different formulations from different manufacturers at room temperature within 7 days.ConclusionsNeglecting adequate processing of surface disinfectant dispensers has contributed to frequent and heavy contamination of use-solutions based on surface active ingredients. Tissue dispenser processing should be taken seriously in clinical practice.

Efficacy of surface disinfectant cleaners against emerging highly resistant gram-negative bacteria

BackgroundWorldwide, the emergence of multidrug-resistant gram-negative bacteria is a clinical problem. Surface disinfectant cleaners (SDCs) that are effective against these bacteria are needed for use in high risk areas around patients and on multi-touch surfaces. We determined the efficacy of several SDCs against clinically relevant bacterial species with and without common types of multidrug resistance.MethodsBacteria species used were ATCC strains; clinical isolates classified as antibiotic-susceptible; and multi-resistant clinical isolates from Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia marcescens (all OXA-48 and KPC-2); Acinetobacter baumannii (OXA-23); Pseudomonas aeruginosa (VIM-1); and Achromobacter xylosoxidans (ATCC strain). Experiments were carried out according to EN 13727:2012 in quadruplicate under dirty conditions. The five evaluated SDCs were based on alcohol and an amphoteric substance (AAS), an oxygen-releaser (OR), surface-active substances (SAS), or surface-active-substances plus aldehydes (SASA; two formulations). Bactericidal concentrations of SDCs were determined at two different contact times. Efficacy was defined as a log10 ≥ 5 reduction in bacterial cell count.ResultsSDCs based on AAS, OR, and SAS were effective against all six species irrespective of the degree of multi-resistance. The SASA formulations were effective against the bacteria irrespective of degree of multi-resistance except for one of the four P. aeruginosa isolates (VIM-1). We found no general correlation between SDC efficacy and degree of antibiotic resistance.ConclusionsSDCs were generally effective against gram-negative bacteria with and without multidrug resistance. SDCs are therefore suitable for surface disinfection in the immediate proximity of patients. Single bacterial isolates, however, might have reduced susceptibility to selected biocidal agents.

Effective reprocessing of reusable dispensers for surface disinfection tissues – the devil is in the details

Background: It has recently been reported that reusable dispensers for surface disinfection tissues may be contaminated, especially with adapted Achromobacter species 3, when products based on surface-active ingredients are used. Fresh solution may quickly become recontaminated if dispensers are not processed adequately. Methods: We evaluated the abilities of six manual and three automatic processes for processing contaminated dispensers to prevent recolonisation of a freshly-prepared disinfectant solution (Mikrobac forte 0.5%). Dispensers were left at room temperature for 28 days. Samples of the disinfectant solution were taken every 7 days and assessed quantitatively for bacterial contamination. Results: All automatic procedures prevented recolonisation of the disinfectant solution when a temperature of 60–70°C was ensured for at least 5 min, with or without the addition of chemical cleaning agents. Manual procedures prevented recontamination of the disinfectant solution when rinsing with hot water or a thorough cleaning step was performed before treating all surfaces with an alcohol-based disinfectant or an oxygen-releaser. Other cleaning and disinfection procedures, including the use of an alcohol-based disinfectant, did not prevent recolonisation. Conclusions: These results indicate that not all processes are effective for processing reusable dispensers for surface-disinfectant tissues, and that a high temperature during the cleaning step or use of a biofilm-active cleaning agent are essential.

Alcohol-based hand rubs must meet the requirements of EN 1500

To the Editor—Kramer et al conducted an interesting study to compare the outcome of different application times (15 seconds and 30 seconds) for hygienic hand disinfection under practical conditions in which they were able to show a significant increase in frequency of hand rub actions when the recommended application time was reduced from 30 seconds to 15 seconds. Although the authors clearly state that only alcohol-based hand rubs (ABHRs) that meet the requirements of the EN 1500 in 15 seconds are suited to be applied with a shortened application time of 15 seconds under practical working conditions, the published results for the different ABHRs do not demonstrate a sufficient efficacy in 15 seconds according to EN 1500. Methods like EN 1500 (phase 2, step 2) offer a standardized procedure to compare the in vivo efficacy of ABHRs under laboratory conditions, and they function as an important criterium in the authorization process of these products independently if they are regulated as medicinal or biocidal products. The EN 1500 procedure specifies how ABHRs must be tested in comparison to a defined reference procedure (2 × 30 seconds; 2 × 3mL 60 % v/v 2-propanol), and it provides statistical requirements that must be fulfilled by the test products. Furthermore, EN 1500 allows the testing of ABHRs only with durations between 30 seconds and 60 seconds. Notably, application times shorter than 30 seconds are not authorized. To obtain meaningful conclusions out of the test results, it is essential that the tests are conducted exactly the way they are described in EN 1500. Kramer et al tested various products covering a broad range of alcohol content following a modified EN 1500 (1997) method. In other words, the test parameters defined in the European Norm were altered in these tests. In addition, an outdated version of the method, which was revised in 2013, was applied, and Kramer et al also modified the reference procedure significantly without providing an explanation for this approach. Compared to EN 1500, in their study, the application volume of the refence alcohol 60% v/v 2-propanol was halved from 6 to 3mL, and the application time was reduced from 60 seconds to 30 seconds. Rotter et al, who investigated the impact of variations in the standard procedure of EN 1500, showed that the shortened duration of the reference procedure (15 seconds or 30 seconds instead of 60 seconds) in combination with half the disinfectant volume (1 × 3mL instead of 2 × 3mL) led to a reduction in the bactericidal efficacy of 2-propanol on the hands. In their tests, the differences were significant between 30 seconds with 3mL and 60 seconds with 2 × 3mL as well as between 15 seconds with 3mL and 60 seconds with 2 × 3mL. Considering these results, the hurdle to success in one of the most stringent standard testing norms, as it was called by Kramer et al, was dramatically lower in their ABHRs in vivo tests following EN 1500. In fact, however, their test design did not follow the EN 1500 method. Therefore, Kramer et al’s conclusion that all tested ABHRs fulfilled EN 1500 in 15 seconds is misleading. Readers should be aware that ABHRs consisting of ethanol in the range of 70% w/w (75% v/v), for example, which were also tested by Kramer et al, did not fulfill the EN 1500 requirement in 30 seconds with 3 mL in other studies. Therefore, it is highly improbable that those products will be effective in 15 seconds if tested according to the EN 1500 method with an application volume of 3mL. We would also like to address the efficacy findings under practical working conditions. Kramer et al observed no significant efficacy differences between the groups rubbing hands for 15 seconds and 30 seconds. This finding is not surprising because in both groups nearly the same amount of ABHRs (3.4mL vs 3.3mL) was applied. Furthermore, “there was no difference in duration for hand antisepsis action between both groups,” as Kramer et al state in the discussion section of their publication. In conclusion, we strongly support all efforts to improve hand hygiene compliance in clinical practice. However, the efficacy of ABHRs should be proven according to established test methods (ie, EN 1500) without modifications that lower their requirements.

O067: Poorly processed reusable dispensers for surface disinfection tissues are a possible source of infection.

Reusable surface disinfectant (SD) tissue dispensers are used in hospitals in many countries because they allow immediate access to soaked tissues for targeted surface decontamination.