Updates and future directions regarding hand hygiene in the healthcare setting: insights from the 3rd ICPIC alcohol-based handrub (ABHR) task force.

Healthcare-associated infections (HAIs) and antimicrobial resistance (AMR) pose threats to global health. Effective hand hygiene is essential for preventing HAIs and the spread of AMR in healthcare. We aimed to highlight the recent progress and future directions in hand hygiene and alcohol-based handrub (ABHR) use in the healthcare setting. In September 2023, 42 experts in infection prevention and control (IPC) convened at the 3rd International Conference on Prevention and Infection Control (ICPIC) ABHR Taskforce in Geneva, Switzerland. The purpose of this meeting was to provide a synthesis of recent evidence and formulate a research agenda on four critical areas for the implementation of effective hand hygiene practices: (1) ABHR formulations and hand rubbing techniques, (2) low-resource settings and local production of ABHR, (3) hand hygiene monitoring and technological innovations, and (4) hand hygiene standards and guidelines.

Evaluation of a microscale quantitative suspension test to determine the bactericidal and yeasticidal activity of glutaral - one step to improve sustainability in disinfectant testing.

Aims: To evaluate a newly developed microscale quantitative suspension test compared to the existing standard suspension test using determination of the bactericidal and yeasticidal activity of glutaral as one step to improve the sustainability of disinfectant testing. Methods: The testing principles of the quantitative suspension test according to VAH method 9 (comparable to EN 13727) was used as a standard suspension test using 8.0 mL product test solution, 1.0 mL organic load and 1.0 mL test suspension. In addition, a micro-scale suspension test was performed in 96-well plates with 160 µL product test solution, 20 µL organic load and 20 µL test suspension. S. aureus ATCC 6538, P. aeruginosa ATCC 15442 and C. albicans ATCC 10231 were test organisms. Glutaral was tested at concentrations of 0.05%, 0.1%, 0.2% and 0.3% with exposure times of 1, 5 and 15 min. Polysorbate 80 (30 g/L), lecithin (9 g/L), L-histidine (1 g/L) and glycine (10 g/L) were used as validated neutralizers. After serial dilution of the disinfectant-neutralizer-mixture, plates were incubated for 48 h at 36°C (bacteria) or 72 hours at 30°C (C. albicans) and colony forming units (cfu) counted. The lg reduction was calculated as the difference between the results of the water control and the disinfectant at the end of the exposure time. All experiments were done in triplicate under clean conditions. Means of lg reduction were compared with the unpaired t-test, p<0.05 was considered to be significant. Results: Sufficient bactericidal activity according the VAH test requirements of at least 5 lg was found with both methods in 16 data sets of 24 data sets in total, and insufficient bactericidal activity of less than 5 lg was found with both methods in 7 data sets. In one data set, the mean lg reduction was above 5 lg with the microscale method and <5 lg with the VAH method, with no significant difference between the data sets (p=0.3096; 0.2% glutaral, 1 min, P. aeruginosa). A sufficient yeasticidal activity of at least 4 lg was found with both methods in one data set, an insufficient yeasticidal activity of less than 4 lg was found with both methods in 8 data sets. With one exception, no significant differences were detected between the two methods below the efficacy threshold. Conclusions: The microscale quantitative suspension test proved to provide results similar to those of VAH method 9 when the bactericidal and yeasticidal activity of glutaralwas evaluated, with 32 out of 33 evaluations yielding consistent results in terms of efficacy. Its suitability should be confirmed with additional bacterial species, additional biocidal active substances and in other laboratories.

Suitable Disinfectants with Proven Efficacy for Genetically Modified Viruses and Viral Vectors.

Viral disinfection is important for medical facilities, the food industry, and the veterinary field, especially in terms of controlling virus outbreaks. Therefore, standardized methods and activity levels are available for these areas. Usually, disinfectants used in these areas are characterized by their activity against test organisms (i.e., viruses, bacteria, and/or yeasts). This activity is usually determined using a suspension test in which the test organism is incubated with the respective disinfectant in solution to assess its bactericidal, yeasticidal, or virucidal activity. In addition, carrier methods that more closely reflect real-world applications have been developed, in which microorganisms are applied to the surface of a carrier (e.g., stainless steel frosted glass, or polyvinyl chloride (PVC)) and then dried. However, to date, no standardized methods have become available for addressing genetically modified vectors or disinfection-resistant oncolytic viruses such as the H1-parvovirus. Particularly, such non-enveloped viruses, which are highly resistant to disinfectants, are not taken into account in European standards. This article proposes a new activity claim known as "virucidal activity PLUS", summarizes the available methods for evaluating the virucidal activity of chemical disinfectants against genetically modified organisms (GMOs) using current European standards, including the activity against highly resistant parvoviridae such as the adeno-associated virus (AAV), and provides guidance on the selection of disinfectants for pharmaceutical manufacturers, laboratories, and clinical users.

The European tiered approach for virucidal efficacy testing - rationale for rapidly selecting disinfectants against emerging and re-emerging viral diseases.

When facing an emerging virus outbreak such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a quick reaction time is key to control the spread. It takes time to develop antivirals and vaccines, and implement vaccination campaigns. Therefore, preventive measures such as rapid isolation of cases and identification and early quarantine of cases' close contacts-as well as masks, physical distancing, hand hygiene, surface disinfection and air control-are crucial to reduce the risk of transmission. In this context, disinfectants and antiseptics with proven efficacy against the outbreak virus should be used. However, biocidal formulations are quite complex and may include auxiliary substances such as surfactants or emollients in addition to active substances. In order to evaluate disinfectants' efficacy objectively, meaningful efficacy data are needed. Therefore, the European Committee for Standardisation technical committee 216 'Chemical disinfectants and antiseptics' Working Group 1 (medical area) has developed standards for efficacy testing. The European tiered approach grades the virucidal efficacy in three levels, with corresponding marker test viruses. In the case of SARS-CoV-2, disinfectants with proven activity against vaccinia virus, the marker virus for the European claim 'active against enveloped viruses', should be used to ensure effective hygiene procedures to control the pandemic.

Virucidal activity of three ethanol-based hand rubs against murine norovirus in a hand hygiene clinical simulation study.

Aim: We evaluated the efficacy of three ethanol-based hand rubs against murine norovirus in a proposed clinical simulation test (prEN 17430). Materials & methods: Virucidal activity was determined in 18 volunteers using three hand rubs: ethanol 72.4 and 89.5% v/v solutions, and 86% v/v gel. Subjects underwent testing with each product (3/6 ml for 15/30 s) and a reference solution (6 ml 70% v/v ethanol for 60 s). Results: Against murine norovirus, the reduction factors (RF; RF mean ± standard deviation log10 reduction of postsampling) for ethanol gel 86% v/v (RF 1.96 ± 0.64), ethanol 89.5% v/v (RF 2.49 ± 0.59) and ethanol 72.4% v/v (RF 2.61 ± 0.50), were all significantly superior to that of the reference solution. Conclusion: All three hand rubs passed the criteria set out in prEN 17430 and exhibited excellent virucidal efficacy.

Evaluation of World Health Organization-Recommended Hand Hygiene Formulations.

As a result of the coronavirus disease pandemic, commercial hand hygiene products have become scarce and World Health Organization (WHO) alcohol-based hand rub formulations containing ethanol or isopropanol are being produced for hospitals worldwide. Neither WHO formulation meets European Norm 12791, the basis for approval as a surgical hand preparation, nor satisfies European Norm 1500, the basis for approval as a hygienic hand rub. We evaluated the efficacy of modified formulations with alcohol concentrations in mass instead of volume percentage and glycerol concentrations of 0.5% instead of 1.45%. Both modified formulations met standard requirements for a 3-minute surgical hand preparation, the usual duration of surgical hand treatment in most hospitals in Europe. Contrary to the originally proposed WHO hand rub formulations, both modified formulations are appropriate for surgical hand preparation after 3 minutes when alcohol concentrations of 80% wt/wt ethanol or 75% wt/wt isopropanol along with reduced glycerol concentration (0.5%) are used.

Chlorhexidine-coated surgical gloves influence the bacterial flora of hands over a period of 3 hours.

Background: The risk of SSI increases in the presence of foreign materials and may be caused by organisms with low pathogenicity, such as skin flora derived from hands of surgical team members in the event of a glove breach. Previously, we were able to demonstrate that a novel antimicrobial surgical glove coated chlorhexidine-digluconate as the active ingredient on its inner surface was able to suppress surgeons' hand flora during operative procedures by a magnitude of 1.7 log10 cfu/mL. Because of the clinical design of that study, we were not able to measure the full magnitude of the possible antibacterial suppression effect of antimicrobial gloves over a full 3 h period. Methods: The experimental procedure followed the method for assessment of the 3-h effects of a surgical hand rub's efficacy to reduce the release of hand flora as described in the European Norm EN 12791. Healthy volunteers tested either an antimicrobial surgical glove or non-antimicrobial surgical latex gloves in a standardized laboratory-based experiment over a wear time of 3 h. Results: Wearing antimicrobial surgical glove after a surgical hand rub with 60% (v/v) n-propanol resulted in the highest 3-h reduction factor of 2.67 log10. Non-antimicrobial surgical gloves demonstrated significantly lower (p ≤ 0.01) 3-h reduction factors at 1.96 log10 and 1.68 log10, respectively. Antibacterial surgical gloves are able to maintain a sustainable bacterial reduction on finger tips in a magnitude of almost 3 log10 (log10 2.67 cfu) over 3 h wear time. Conclusion: It was demonstrated that wear of an antibacterial surgical glove coated with chlorhexidine-digluconate is able to suppress resident hand flora significantly over a period of 3-h.

How long is enough? Identification of product dry-time as a primary driver of alcohol-based hand rub efficacy.

Background: The World Health Organization has called for the development of improved methodologies to evaluate alcohol-based handrub (ABHR) efficacy, including evaluation at "short application times and volumes that reflect actual use in healthcare facilities". The objective of this study was to investigate variables influencing ABHR efficacy, under test conditions reflective of clinical use. Methods: The test product (60% V/V 2-propanol) was evaluated according to a modified EN 1500 methodology, where application volumes of 1 mL, 2 mL, and 3 mL were rubbed until dry. Statistical analyses were performed to investigate the relative influences of product volume, hand size, and product dry-time on efficacy, and hand size and hand contamination on product dry-time. Results: Mean log10 reduction factors (SD) were 1.99 (0.66), 2.96 (0.84) and 3.28 (0.96); and mean dry-times (SD) were 24 s (7 s), 50 s (14 s), and 67 s (20 s) at application volumes of 1 mL, 2 mL, and 3 mL, respectively (p ≤ 0.030). When data were examined at the individual volunteer level, there was a statistically significant correlation between dry-time and log reduction factor (p < 0.0001), independent of application volume. There was also a statistically significant correlation between hand surface area and dry-times (p = 0.047), but no correlation between hand surface area and efficacy (p = 0.698). Conclusions: When keeping other variables such as alcohol type and concentration constant, product dry-time appears to be the primary driver of ABHR efficacy suggesting that dosing should be customized to each individual and focus on achieving a product dry-time delivering adequate efficacy.

Influence of glycerol and an alternative humectant on the immediate and 3-hours bactericidal efficacies of two isopropanol-based antiseptics in laboratory experiments in vivo according to EN 12791.

BACKGROUND: Guidelines for hand hygiene recommend the use of alcohol-based hand rubs containing humectants in order to improve dermal tolerance. However, the bactericidal efficacy of pre-surgical hand rubs is negatively affected by the WHO-recommended humectant glycerol, especially the 3-h efficacy. The aim of this study was to investigate whether replacing glycerol as humectant increases the bactericidal efficacy of surgical hand rubs based on isopropanol (75%, wt/wt). MATERIAL AND METHODS: The efficacy of 3 and 5 min applications of a modified WHO II-formulation (containing lower glycerol concentrations) and the TPH 5766 hand rub which contains a new humectant (containing ethylhexylglycerin, dexpanthenol and a fatty alcohol) were compared to the European Norm 12,791 reference (n-propanol, 60%, vol/vol) immediately following and 3 h after application. RESULTS: Immediately after application both isopropanol-based surgical rubs approximated the performance of the reference. The 3-h effect of the modified WHO II-formulation was found to be less efficacious than the EN 12791, showing a 30% decrease in log10 reduction values. The 3-h post application effect for the TPH 5766 hand rub was found to not be different from EN 12791. CONCLUSION: Based on our data, the bactericidal efficacy of isopropanol-based surgical hand rubs can best be obtained if glycerol is not used in the formulation. Unlike glycerol, a humectant comprised of ethylhexylglycerin, dexpanthenol and a fatty alcohol was found not to decrease hand rub effectiveness. Further investigation of the bactericidal efficacy of other humectants is necessary and may prove useful.

Suppression of surgeons' bacterial hand flora during surgical procedures with a new antimicrobial surgical glove.

BACKGROUND: Perforations of surgical gloves are common and increase with the duration of glove wear. Skin flora, re-grown after pre-operative disinfection of the hands, may contaminate a surgical site. An antimicrobial surgical glove with chlorhexidine on its inner surface has been developed. We hypothesized that by suppressing the re-growth of skin flora during the complete course of a surgical procedure, antimicrobial gloves may reduce the risk of surgical site contamination in the event of an intra-operative glove breach. METHODS: We conducted a randomized, double-blind, single-center trial, to measure any differences in the bacterial skin populations of surgeons' hands during surgical procedures done with antimicrobial and non-antimicrobial surgical gloves [ISRCTN71391952]. In this study, 25 pairs of gloves were retrieved from 14 surgeons who donned them randomly on their dominant or non-dominant hand. The number of bacteria retrieved from glove fluid was measured and expressed as colony forming units (CFU)/mL. RESULTS: The median cfu/mL of antimicrobial gloves was 0.00 (LQ: 0.00 CFU/mL; UQ: 0.00 cfu/mL), with a mean log10 cfu/mL=0.02 (range: 0.00-0.30). The median CFU/mL of non-antimicrobial gloves was 54.00 (LQ: 3.00 cfu/mL; UQ: 100.00 cfu/mL) with a mean log10 CFU/mL=1.32 (range: 0.00-2.39). After a mean operating time of 112 min, the difference in the log10 CFU/mL was 1.30 (p<0.001). CONCLUSIONS: A new antimicrobial surgical glove suppressed surgeons' hand flora during operative procedures. In the event of a glove breach, the use of such a glove may have the potential to prevent bacterial contamination of a sterile surgical site, thereby decreasing the risk of surgical site infection (SSI) and increasing patient safety. Further clinical studies are needed to confirm this concept.

Influence of pre- and post-usage flushing frequencies on bacterial water quality of non-touch water fittings.

BACKGROUND: Non-touch fittings have been reported to be susceptible for Pseudomonas aeruginosa accumulation. A number of factors may contribute to this, including the frequency of usage, duration of water stagnation, or presence of plastic materials. Programmable non-touch fittings are appearing which allow regular automated post-flushing with cold water to prevent water stagnation. However, the ideal duration of post-flushing is unknown as well as the effect of pre-rinsing with cold water before use. METHODS: Eight non-touch fittings with brass valve blocks were mounted on a mobile test sink and connected to the same central water pipe source, differing only in presence or absence of water connection pipes, length of connection pipe, frequency of usage, and time intervals for pre- and post-usage water flush. The total bacteria colony-forming unit (cfu) counts were obtained by the spread plate technique. RESULTS: Low frequency of water use in combination with a long stagnating water column resulted in high bacterial cfu counts. Post-usage flushing for 2 seconds did not differ from no flushing. Flushing for 10 seconds with cold water after use or 30 seconds flush before use were both the most effective measures to prevent non-touch fittings from biofilm formation over a period of 20 weeks. CONCLUSION: Further improvements in water fitting technology could possibly solve the problem of bacterial water contamination in health care settings.

Efficacy of hand rubs with a low alcohol concentration listed as effective by a national hospital hygiene society in Europe.

BACKGROUND: Some national hospital hygiene societies in Europe such as the French society for hospital hygiene (SFHH) have positive lists of disinfectants. Few hand disinfectants with a rather low concentration of ethanol are listed by one society as effective for hygienic hand disinfection with 3 mL in 30 s including a virucidal activity in 30 s or 60 s, but published data allow having doubts. We have therefore evaluated the efficacy of three commonly used hand disinfectants according to EN 1500 and EN 14476. METHODS: Products 1 (Aniosgel 85 NPC) and 2 (Aniosrub 85 NPC) were based on 70% ethanol, product 3 (ClinoGel derma+) on 60% ethanol and 15% isopropanol (all w/w). They were tested in 3 laboratories according to EN 1500. Three mL were applied for 30 s and compared to the reference treatment of 2 × 3 mL applications of isopropanol 60% (v/v), on hands artificially contaminated with Escherichia coli. Each laboratory used a cross-over design against the reference alcohol with 15 or 20 volunteers. The virucidal activity of the products was evaluated (EN 14476) in one laboratory against adenovirus and poliovirus in different concentrations (80%, 90%, 97%), with different organic loads (none; clean conditions; phosphate-buffered saline) for up to 3 min. RESULTS: Product 1 revealed a mean log10-reduction of 3.87 ± 0.79 (laboratory 1) and 4.38 ± 0.87 (laboratory 2) which was significantly lower compared to the reference procedure (4.62 ± 0.89 and 5.00 ± 0.87). In laboratory 3 product 1 was inferior to the reference disinfection (4.06 ± 0.86 versus 4.99 ± 0.90). Product 2 revealed similar results. Product 3 fulfilled the requirements in one laboratory but failed in the two other. None of the three products was able to reduce viral infectivity of both adenovirus and poliovirus by 4 log10 steps in 3 min according to EN 14476. CONCLUSIONS: Efficacy data mentioned in a positive list published by a society for hospital hygiene should still be regarded with caution if they quite obviously contradict published data on the same or similar products.

Modified World Health Organization hand rub formulations comply with European efficacy requirements for preoperative surgical hand preparations.

BACKGROUND: The World Health Organization (WHO) has published "Guidelines on Hand Hygiene in Health Care" recommending 2 hand rub formulations based on 80% vol/vol ethanol or 75% vol/vol isopropanol for local production in healthcare settings where commercial products are not available or are too expensive. Previous investigations have shown that neither formulation meets the efficacy requirements of European norm (EN) 12791, which is the most stringent available norm for surgical hand rub preparations. Even when modified with approximately 5% higher alcohol content, the formulations proved to be inferior to the reference of the norm when measured after 3 hours. OBJECTIVE: Because the high glycerol content of the formulations was suspected to negatively influence their efficacy, additional investigations were performed with varying glycerol content. METHODS: Modified formulations with higher alcohol concentration (mass instead of volume percentage) and lower glycerol concentration (0.725% instead of 1.45%) or without the addition of glycerol were evaluated for their conformity with the efficacy requirements of EN 12791, which demands noninferiority in comparison with a reference hand antisepsis procedure immediately and 3 hours after treatment on volunteers' hands. DESIGN: Randomized Latin-square design. SETTING: Microbiology laboratory of the Medical University of Vienna, Vienna, Austria. PARTICIPANTS: Twenty-five healthy volunteers. RESULTS: Reducing the concentration of glycerol or omitting it completely rendered both WHO formulations noninferior to the reference, both immediately and 3 hours after surgical hand antisepsis. CONCLUSIONS: Both WHO-recommended formulations meet the efficacy requirements of EN 12791 by increasing their alcohol concentrations by 5%, prolonging their application to 5 minutes and reducing the glycerol concentration to 0.725%.

Recommendations and requirements for soap and hand rub dispensers in healthcare facilities.

Hand hygiene is one of the most important measures to prevent transmission of infectious agents and plays a major role in prevention of infection in any type of healthcare setting. While requirements for the efficacy of hand disinfectants are defined in European testing norms such as the EN 1500 for hygienic hand disinfection or EN 12791 for surgical hand preparation, no specific recommendations for hand rub dispensers and liquid soap dispensers have been given yet. Therefore, the intention of the present recommendation on soap and hand rub dispensers in healthcare facilities is to close this gap and to enhance future improvement of dispenser functionality and design. Regardless of manufacture and design of a hand rub or liquid soap dispensers the following requirements shall be met in healthcare facilities:Triggering the dispenser must be possible without using hands. Sensor- or elbow-operated dispensers both fulfill this requirement. Dispensers must be only refillable in a modality where the content, be it a hand rub or liquid soap, cannot be contaminated. This is achieved best by using replaceable cartridge systems. Refilling through "top-up" must not be possible. The disperser should allow usage of different types of cartridges made by different manufacturers. Dispensers must be operated and maintained such that a microbial contamination of the pump nozzle may easily be avoided. It must be possible to identify the products used in a dispenser easily and without any manipulation. Identifying the type of product, be it a hand rub or a liquid soap, as well as reading the product's name and critical manufacturers' warnings must be possible at any time. The disperser must allow identification of the level of the used product without any further manipulation at any time. The design of the dispenser must allow easy cleaning and disinfection the outside and inside of the dispenser. The manufacturer of the dispenser must provide the user with information on applicable chemicals and cleaning products. It must be possible to reprocess the dispenser and all of its permanent parts by applying machine based thermal disinfection at an A(0)-value of minimum 60 (e.g. 80°C/1 minute). Automatically portioning dispensers shall not fail during 200 hubs. The maximal allowed failure rate shall not exceed 1% (2 out of 200 consecutive hubs). A dispenser used for alcohol based hand rubs must allow keeping the alcohol concentration constant over a time period of 3 months. The maximum acceptable decrease in the concentration of the alcohol shall not exceed 5%. Liquid soap and hand rub dispensers with single-use pumps, ideally already mounted on the cartridge and to be discharged with the empty cartridge, are preferable. If pumps are used on the next consecutive cartridge, the manufacturer must provide the user with a detailed introduction for cleansing and reprocessing before further use. Because of forensic reasons it is recommended to place a good readable sign on the dispenser indicating e.g. "Apply alcohol based hand rubs only on the hand! Do not drink, avoid spraying into the eye or application on mucous membranes". It is regarded as an additional benefit, if the dispenser is able to document the consumption of hand rub or the frequency of hubs either mechanically or electronically.

Testing of the World Health Organization recommended formulations in their application as hygienic hand rubs and proposals for increased efficacy.

BACKGROUND: In Central Europe, alcohol-based hand rubs have been the preferred choice for hand hygiene, whereas, in other countries, other preparations have been used that are based on other active agents. Recently, a move towards alcohol-based hand rubs has begun, but they may be costly and unaffordable to some. Therefore, the World Health Organization (WHO) has recommended 2 hand rub formulations (WHO I and WHO II) for local production in health care settings where commercial products are not available or are too expensive. OBJECTIVES: WHO I, based on ethanol 80% (vol/vol), and WHO II, based on isopropanol 75% (vol/vol), were investigated for their bactericidal efficacy in their application as hygienic hand rubs. METHODS: The investigation took place at the Institute for Hygiene and Applied Immunology, Medical University Vienna, Austria, as a prospective, randomized, in vivo laboratory study, comparative in crossover design. Both formulations were tested according to the European Standard EN 1500 in 2 applications (1 × 3 mL/30 seconds or 2 × 3 mL/2 × 30 seconds). Additionally, modifications with increased alcohol concentrations (weight instead of volume percent) were tested in the short application. Bactericidal efficacies were compared with those of the respective reference procedure "R," ie, rubbing 2 × 3 mL 60% vol/vol isopropanol for 2 × 30 seconds onto hands artificially contaminated with Escherichia coli K12. RESULTS: The short application of either WHO formulation resulted in bacterial reductions significantly inferior to the respective ones of R. However, prolonging the contact time to 60 seconds or increasing the alcohol content produced reductions similar to those of R. CONCLUSION: Both WHO-recommended formulations meet the efficacy requirements of EN 1500 within 60 seconds but not within 30 seconds. Increasing the respective alcohol concentrations from 80% vol/vol to 80% wt/wt and 75% vol/vol to 75% wt/wt renders the formulations sufficiently active to conform to the norm also within 30 sections.

Time-dependent effects of rifampicin on staphylococcal biofilms.

OBJECTIVE: To test the time-dependent effects of rifampicin on established biofilms of Staphylococcus epidermidis isolated from patients with cardiac implant infections and catheter-related bacteremia. METHODS: Biofilms were grown in microtiter plates for 24 hours, dyed and stained with crystal violet. The mean optical density (OD) was used for quantification. The OD ratio (ODr = OD of the treated biofilm/OD of the untreated biofilm) was used to measure changes in the thickness of the biofilms over the time. Biofilms were incubated with rifampicin (0.6 mg/mL) for 1, 5, 15, 30 and 60 minutes. Unstained biofilms were sonicated and plated on Columbia agar for time-kill curves. RESULTS: The incubation of the biofilms with rifampicin led to a significant reduction of the OD of the biofilms within 1 minute (ODr baseline: 1; ODr 1 min: 0.333 ± 0.131) (p<0.001). With regard to bacterial killing, rifampicin reduced the mean log count, but viable bacteria were still grown from biofilms in 13 out of 28 isolates despite MIC values < 0.01 mg/L. CONCLUSIONS: In conclusion, our results confirm that rifampicin at a concentration of 1.2 mg/mL immediately reduces established biofilms formed by S. epidermidis although it is not bactericidal despite very low MICs at planktonic conditions.

Anti-acanthamoeba efficacy and toxicity of miltefosine in an organotypic skin equivalent.

OBJECTIVES: Acanthamoebae can cause infections of several organs, including eye, skin, lung and brain. Except for Acanthamoeba keratitis, these infections are linked to immunodeficiency. Treatment is generally problematic, due to the lack of sufficiently effective and also easily manageable drugs. In a previous study we discovered that miltefosine (hexadecylphosphocholine) is highly active against Acanthamoeba spp. in vitro. The aim of the current study was to evaluate the suitability of miltefosine for the topical treatment of Acanthamoeba infections. METHODS: Storage life and time dependency, susceptibilities of opportunistic bacterial and fungal pathogens, and synergistic and adverse effects of combinations with other anti-Acanthamoeba substances were determined. Moreover, an organotypic skin equivalent was adapted for investigating the penetration of acanthamoebae into the epidermis and the human tissue tolerability of miltefosine. RESULTS: It was shown that miltefosine can be stored as a 2 mM stock solution and also as a 50 microM dilution over a period of 12 months at 4 degrees C without any loss of activity. Efficacies against staphylococci and Candida albicans were established. Acanthamoebae were able to penetrate the skin equivalent within 24 h. This penetration was prevented by treatment with miltefosine, while miltefosine treatment was well tolerated by the skin equivalent. CONCLUSIONS: Miltefosine has been approved for oral and topical treatment of leishmaniasis and may also be a promising candidate for the topical treatment of Acanthamoeba infections.

Surgical hand rub: Influence of duration of application on the immediate and 3-hours effects of n-propanol and isopropanol.

BACKGROUND: The recommended duration for surgical hand treatment has been changed from 10 over 5 to 3 minutes and even shorter. OBJECTIVES: Our objective was to study the impact of the length of surgical hand antisepsis with n-propanol 60% (vol/vol) or isopropanol 70% (vol/vol) applied for 1, 3, or 5 minutes on the reduction of resident hand flora in the setting of the microbiologic laboratory for experimental and applied testing of disinfectants and antiseptics at the Medical University Vienna, Austria, using a Latin Square design. METHODS: Our methods were according to the Austrian Guidelines for Testing Products for Surgical Hand Antisepsis. The release of bacterial hand flora of 21 subjects is assessed before and immediately after disinfection from one hand and 3 hours later from the other, meanwhile gloved, hand. Mean reduction factors (RF) are calculated. RESULTS: The immediate mean log(10) RFs with n-propanol or isopropanol were 1.05, 2.03, and 2.30 and 0.74, 1.48, and 2.12, respectively, when applied for 1, 3, or 5 minutes, respectively. After 3 hours, the respective mean log(10) RFs were 0.45, 1.01, and 1.60 and 0.19, 0.79, and 1.03. Thus, with increasing length of application, a highly significant trend (P < .001) toward higher log(10) reductions was demonstrated. At both sampling times, n-propanol was more effective than isopropanol at the corresponding treatments. Furthermore, a highly significant (P < .001) association was found between the individual volunteers and the effect of the antiseptics on their hands. CONCLUSION: The efficacy of surgical antisepsis is significantly associated with the length of application.

Effects of alcohols, povidone-iodine and hydrogen peroxide on biofilms of Staphylococcus epidermidis.

OBJECTIVES: To test the effects of several biocides [N-propanol, a commercially available propanol/ethanol/chlorhexidine mixture, polyvinylpyrolidone (povidone-iodine) and hydrogen peroxide] on established biofilms of Staphylococcus epidermidis isolated from patients with cardiac implant infections and catheter-related bacteraemia. METHODS: Biofilms were grown in microtitre plates for 24 h, dyed and stained with Crystal Violet. The mean optical density (OD) and the OD ratio (ODr=OD of the treated biofilm/OD of the untreated biofilm) were used for quantification. Biofilms were incubated with 60% (v/v) N-propanol, the mixture of propanol/ethanol/chlorhexidine, hydrogen peroxide at three concentrations (0.5%, 3% and 5%, v/v) and povidone-iodine for 1, 5, 15, 30 and 60 min. Unstained biofilms were sonicated and plated on Columbia agar for time-kill curves. S. epidermidis skin isolates from healthy volunteers were used as controls. RESULTS: Biofilm ODs of the clinical S. epidermidis isolates and the isolates from the healthy volunteers were significantly different (1.17+/-0.512 versus 0.559+/-0.095, respectively; mean+/-SD) (P<0.01). No viable S. epidermidis was detected in biofilms treated with the alcohols, N-propanol or the propanol/ethanol/chlorhexidine mixture. Incubation with povidone-iodine and hydrogen peroxide 3% and 5% led to a log reduction of the viable cells of >5 after incubation for 5 min, however, up to 10(3) viable cells were detected in four isolates after 30 min of incubation with povidone-iodine. CONCLUSIONS: S. epidermidis obtained from infected implants forms thicker biofilms than that of healthy volunteers. Hydrogen peroxide, at a concentration of 3% and 5%, and alcohols rapidly eradicate S. epidermidis biofilms, whereas povidone-iodine is less effective.