Miranda Suchomel

Population kinetics of the skin flora on gloved hands following surgical hand disinfection with 3 propanol-based hand rubs: a prospective, randomized, double-blind trial.

OBJECTIVE To study the bacterial population kinetics on gloved hands following hand treatment with 3 optically indistinguishable, alcohol-based surgical hand rubs, with and without supplements to delay bacterial regrowth. DESIGN Prospective, randomized, double-blind, balanced quasi-Greco-Latin square design. SETTING Microbiology laboratory of the Medical University Vienna, Austria. PARTICIPANTS Twenty-four healthy adult volunteers without skin lesions. Surgical hand rubs. The following hand rubs, all stained blue, were applied to the hands for 3 minutes: 1-propanol 60% vol/vol (A); 2-propanol 70% m/m plus chlorhexidine gluconate 0.5% wt/wt (B); 2-propanol 45% wt/wt plus 1-propanol 30% wt/wt plus mecetronium etilsulfate 0.2% wt/wt (C). As a reference formulation (R), 1-propanol 60% vol/vol, unstained, was applied for the same amount of time. METHOD In 8 once-weekly tests, 24 subjects randomly assigned to use the 4 hand rubs in groups of 6 persons each performed hand hygiene according to the method described in European Norm 12791. Every subject used one preparation at a time, the antimicrobial effect of which was evaluated at 2 sampling times. After week 8, each volunteer had tested every preparation at every preset sampling time. All preparations were tested in parallel. RESULTS The mean pretreatment counts of viable bacteria (in colony-forming units per milliliter) in fluid samples were not significantly different between week 1 and week 8, nor between the right and left hands (analysis of variance [ANOVA], P>.1). Immediately after applying the formulation (t(0)), bactericidal effects of the blinded formulations A and C were equivalent to that of the reference formulation R, whereas the effect of B was questionable. The population kinetics of the flora on the hands proceeded from large and fast initial reductions of the skin flora by 2.7 log units (A), 3.1 log units (B), 3.3 log units (reference formulation), and 3.5 log units (C), to slow regrowth. However, even after 6 hours wearing gloves viable bacterial counts remained significantly (P<.01) below the baseline values (by 0.9 log [reference formulation], 1.1 log [A and B], and 1.5 log [C]). The slowest regrowth 1 and 3 hours after application (Delta from t(0), 0.1 log and 0.7 log respectively) was seen with formulation C, and the slowest regrowth after 6 hours was seen with formulation B (Delta from t(0), 1.6 log). These differences did, however, not reach statistical significance. CONCLUSIONS With respect to the rapid and dramatic antibacterial action of suitable alcohols at high concentrations and with appropriate neutralizers, the contribution of supplements to the delay of bacterial regrowth on gloved hands appears rather minor, if a product only exerts an immediate effect equivalent to that of the reference disinfection procedure described in EN 12791.

Surgical hand disinfection using alcohol: the effects of alcohol type, mode and duration of application.

Due to their strong antimicrobial activity, rapid action, good dermal tolerance and ease of application, alcohol-based hand rubs are recommended for pre-operative preparation of the surgical teams hands. Using the EN 12791 protocol, three commercial products containing either mixtures of propan-1-ol and propan-2-ol or ethanol at total alcohol concentrations (w/w) between 73% (propanols) and 78.2% (ethanol), as the main active agents, were tested with a shortened application of 1.5 min rather than the usual 3 min. Preparation A containing 30% propan-1-ol and 45% propan-2-ol not only passed the test at this short application but even exceeded, though not significantly, the efficacy of the reference disinfection procedure in EN 12791 when applied for 3 min. Preparation B containing 45% propan-1-ol and 28% propan-2-ol fulfilled the required standard whereas the ethanol (78.2%)-based product C did not (P<0.1). This demonstrates that some, but not all, alcohol-based hand rubs pass the test even within 1.5 min, emphasising the importance of validation before a product is introduced into clinical practice. In another series with both preparation A and 60% v/v propan-1-ol, it was demonstrated that the additional inclusion of the forearms into the disinfection procedure, not required by EN 12791 but normal practice in surgical hand disinfection, does not significantly interfere with the antimicrobial efficacy of either hand rub. Therefore, the mode of test procedure in EN 12791 does not need specific adaptation for hand disinfection by surgical teams.

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.

Testing of the World Health Organization-recommended formulations for surgical hand preparation and proposals for increased efficacy

The 2009 World Health Organization (WHO) Guidelines on hand hygiene in health care recommend alcohol-based hand rubs for both hygienic and pre-surgical hand treatment. Two formulations based on ethanol 80% v/v and 2-propanol 75% v/v are proposed for local preparation in healthcare settings where commercial products are not available or too expensive. Both formulations and our suggested modifications (using mass rather than volume percent concentrations) were evaluated for their conformity with the efficacy requirements of the forthcoming amendment of the European Norm (EN) 12791, i.e. non-inferiority of a product when compared with a reference procedure (1-propanol 60% v/v for 3 min) immediately and 3 h after antisepsis. In this study, the WHO-recommended formulations were tested for 3 min and 5 min. Neither formulation met the efficacy requirements of EN 12791 with 3 min application. Increasing the respective concentrations to 80 w/w (85% v/v) and 75 w/w (80% v/v), together with a prolonged application of 5 min, rendered the immediate effect of both formulations non-inferior to the reference antisepsis procedure. This was not the case with the 3h effect, which remained significantly inferior to the reference. Although the original formulations do not meet the efficacy requirements of EN 12791, the clinical significance of this finding deserves further clinical trials. To comply with the requirement of EN 12791, an amendment to the formulations is possible by increasing the alcohol concentrations through changing volume into mass percent and prolonging the duration of application from 3 min to 5 min.

Ethanol in pre-surgical hand rubs: concentration and duration of application for achieving European Norm EN 12791

In Europe, ethanol is a common active agent in hand rub formulations and nowadays it is also recommended in guidelines for hand hygiene published by the Centers for Disease Control and Prevention and by the World Health Organization. However, data on the range of concentrations and durations of application providing a basis for passing the efficacy test of the European norm EN 12791 are still lacking. Therefore, the bactericidal efficacy of rubbing clean hands with pure ethanol in volume concentrations of 95%, 85% or 75% during 3 min was compared with that of the reference procedure of EN 12791 employing n-propanol 60% v/v for 3 min, immediately and 3h after disinfection. Ethanol 85% was also tested at a 5 min application. A Latin-square design was used with 20 randomly allotted volunteers. Whereas the mean immediate bacterial reductions caused by ethanol at concentrations of 75% (log RF 1.68) and 95% (log RF 2.70) were significantly less efficacious compared to that of the reference (log RF 3.27), at 85% they were not significantly less active with both applications, 3 and 5 min (log RFs 2.90 and 3.12, respectively). Three hours after antisepsis, the bacterial reduction on the gloved hand was only significantly less efficacious than that of the reference when 75% ethanol was used. It is concluded that ethanol-based hand rubs have a good chance of meeting the EN 12791 requirements if their ethanol concentration is >75% v/v but <95% v/v and if they are applied for at least 3 min.

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.

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

BackgroundNon-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.MethodsEight 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.ResultsLow 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.ConclusionFurther improvements in water fitting technology could possibly solve the problem of bacterial water contamination in health care settings.