Antimicrobial efficacy of alcohol-based hand gels

Journal of Hospital Infection (2010) 74, 219e224

Available online at www.sciencedirect.com

www.elsevierhealth.com/journals/jhin

Antimicrobial efficacy of alcohol-based hand gels M. Guilhermetti, L.A. Marques Wiirzler, B. Castanheira Facio, M. da Silva Furlan, W. Campo Meschial, M.C. Bronharo Tognim, L. Botelho Garcia, C. Luiz Cardoso* Department of Clinical Analyses, State University of Maringa´, Maringa´, Parana´, Brazil Received 18 March 2009; accepted 11 September 2009 Available online 12 January 2010

KEYWORDS Alcohol-based hand gels; Alcohol-based hand rinses; EN 1500; Hand hygiene

Summary In recent years, several commercial alcohol-based hand gels have appeared on the market to improve the hand-cleansing compliance of healthcare workers. Although the antimicrobial efficacy of these products has been reported in different countries, few studies have investigated this subject in Brazil. In this study, we assessed the antimicrobial efficacy of 12 alcohol-based hand gels produced in Brazil, containing 70% w/w or v/v ethyl alcohol as the active ingredient, according to the European Standard EN 1500 (EN 1500). The following alcohol gels were tested: Hand Gel, Voga Gel, Solumax Solugel, Doctor Clean, Rio Gel, Clear Gel, Sevengel, Hand CHC, Gel Bac, WBL-50 Gel, Sanigel and Soft Care Gel. In addition, 70% w/w ethyl alcohol and three alcohol-based hand rubs (Sterillium, Sterillium Gel, and Spitaderm), commonly used in Europe and effective according to EN 1500, were also tested. All the products tested, except for two, were approved by the EN 1500 test protocol with a 60 s application. The results confirmed the antimicrobial efficacy of the majority of the alcohol gels produced in Brazil for hand hygiene of healthcare workers. ª 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.

Introduction Hand hygiene, including hand washing (plain soap) and hand disinfection (antimicrobial soap or * Corresponding author. Address: Laborato ´rio de Microbiologia (Bloco I-90, Sala 116), Departamento de Ana ´lises Clı´nicas, Universidade Estadual de Maringa ´, Avenida Colombo 5790, CEP 87020-900 Maringa ´, Parana ´ , Brazil. Tel.: þ55 44 3261 4953; fax: þ55 44 3261 4860. E-mail address: [email protected]

alcohol), remains the single most important procedure for preventing nosocomial infections, since many of these infections may be caused by microorganisms transmitted via the contaminated hands of healthcare personnel.1e4 Observational studies have shown that compliance of hospital personnel with recommended hand-hygiene procedures has been poor, however, with mean baseline rates of 5e89%, representing an overall average of 38.7%.5 The main factors that

0195-6701/$ - see front matter ª 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2009.09.019

220 may contribute to this low compliance include lack of time, skin irritation from frequent hand hygiene, high workload and understaffing, forgetfulness, excessive use of gloves, poor access to sinks, and inadequate knowledge of hand-hygiene recommendations.2,5,6 In recent years, after the appearance of new guidelines for hand hygiene from the Centers for Disease Control and Prevention and World Health Organization that promote the use of alcoholbased preparations as standard procedures for hand hygiene in healthcare settings, several commercial alcohol-based hand gels have appeared in the market, with the objective of improving handhygiene compliance.2,5 The antimicrobial efficacy of these products has been reported in several studies but few researchers have investigated this subject in Brazil.6e14 In the present study, we assessed the antimicrobial efficacy of 12 alcohol-based hand gels produced in Brazil according to European Norm 1500 (EN 1500).15 In addition, 70% w/w ethyl alcohol and three alcohol-based hand rubs (Sterillium, Spitaderm, and Sterillium Gel) commonly used in Europe and effective according to EN 1500 were also tested.

Methods Subjects The group of volunteers enrolled in this study included 34 healthy adults, being 10 males and 24 females, with no skin problems. The volunteers were students, technicians, and faculty members at the State University of Maringa ´. Their ages ranged from 18 to 58 years. Before beginning the experiments, all volunteers were trained to perform the standard rub-in technique according to EN 1500, because an inadequate hand-rub technique may adversely affect the tests.15,16 The study was approved by the institutional review board; written consent was obtained from all volunteers.

Alcohol-based hand gels and rinses The following alcohol-based hand gels were used: (i) Hand Gel (Prolim Quı´mica Avanc ¸ada Ltda); (ii) Voga Gel (Essenbra); (iii) Solumax Solugel (Luvex ~o Ltda); (iv) Indu ¸a ´stria e Equipamentos de Protec Doctor Clean (Bulle de Savon Cosme ´ticos Ltda); (v) Rio Gel (Indu ˆutica Rioquı´mica Ltda); ´stria Farmace (vi) Clear Gel (Jofel do Brasil Indu ´rcio ´stria e Come Ltda); (vii) Sevengel (Sevengel Indu ´rcio ´stria e Come Ltda ME); (viii) Hand CHC (Adhetech Quı´mica

M. Guilhermetti et al. Indu ´rcio Ltda); (ix) Gel Bac (Proline ´stria e Come Indu stria e Come ´rcio Ltda); (x) WBL-50 Gel (Walde´ nir B. Lichtenthaler); (xi) Sanigel (Essenbra); (xii) Soft Care Gel (Johnson Diversey do Brasil). All these gels were produced in Brazil, and contained 70% ethyl alcohol as the active ingredient by weight (i, ii, iii, v, vi, vii, xi, and xii) or volume (iv, viii, ix, and x). Sterillium Gel, based on 85% w/w ethyl alcohol (Bode Chemie GmbH & Co. KG, Hamburg, Germany) was also tested. In addition, the following alcohol-based hand rinses were tested: (i) 70% ethyl alcohol, prepared at the moment of use by mixing 70 g absolute ethyl alcohol (Merck KGaA, Darmstadt, Germany) and 30 g distilled water; (ii) Sterillium, based on 45% 2-propanol, 35% 1-propanol, and 0.2% mecetronium ethylsulphate (Bode Chemie); (iii) Spitaderm, based on 70% 2-propanol, 0.5% chlorhexidine digluconate, and 0.45% hydrogen peroxide (Henkel Ecolab GmbH, Du ¨sseldorf, Germany).

Assessment protocol The antimicrobial efficacy of alcohol-based preparations was assessed according to EN 1500.15 Briefly, EN 1500 requires 12e15 test volunteers and a 24 h broth culture of Escherichia coli K12. Hands are washed with a soft soap, dried, and then immersed halfway to the metacarpals in the broth culture for 5 s. Hands are removed from the broth culture, excess fluid is drained off, and hands are dried in the air for 3 min. Bacterial recovery for the initial value is obtained by rubbing the fingertips of each hand separately for 1 min in 10 mL of nutrient broth without neutralisers. The hands are removed from the broth and disinfected with 3 mL of the hand-rub agent for 30 s in a set design. The same operation is repeated with total disinfection time not exceeding 60 s. Both hands are rinsed in running water for 5 s and the water is drained off. Fingertips of each hand are rubbed separately in 10 mL of nutrient broth with added neutralisers. These broths were used to obtain the post-treatment values. Log10 dilutions of recovery medium are prepared and plated out. Within 3 h, the same volunteers are tested with the reference disinfectant (60% 2propanol) and the test product. Colony counts are performed after 24 and 48 h of incubation at 36  C. The average colony count of both left and right hand is used for evaluation. A log-reduction factor (log RF) is calculated and compared with the initial and final values. For acceptance, the log RF of the test product should not be inferior to the reference alcohol-based rub. If this is the case, then the results are analysed statistically

Antimicrobial efficacy of alcohol gel Table I 1500

221

Bactericidal efficacy of 70% (w/w or v/v) ethanol-based hand gels and rinses according to European Norm

Product

Hand gels Hand Gel Voga Gel Solumax Solugel Doctor Clean Rio Gel Clear Gel Seven Gel Hand CHC Gel-Bac WBL50 Gel Sanigel Soft Care Gel Sterillium Gel Hand rinses 70% ethanol Sterillium Spitaderm

Active ingredients

70% 70% 70% 70% 70% 70% 70% 70% 70% 70% 70% 70% 85%

w/w ethanol w/w ethanol w/w ethanol v/v ethanol w/w ethanol w/w ethanol w/w ethanol v/v ethanol v/v ethanol v/v ethanol w/w ethanol w/w ethanol w/w ethanol

70% w/w ethanol 2-Propanol 45% and 1-propanol 30% plus 0.2% mecetronium ethylsulphate 2-Propanol 70% plus 0.5% chlorhexidine digluconate plus 0.45% hydrogen peroxide

Mean log RF of reference alcohola

Mean log RF of product

Difference

4.18 4.10 4.42 4.18 4.21 4.34 4.47 4.14 4.05 4.15 3.71 4.15 4.23

4.62 3.84 4.01 4.25 4.48 4.12 4.29 4.34 3.92 2.41 3.71 4.10 4.73

0.44 0.26 0.41 0.07 0.27 0.22 0.18 0.20 0.13 1.74  0.05 0.50

3.99 4.02

3.99 4.98

 0.96

4.21

4.67

0.46

P-valueb

NS <0.1

NS NS NS <0.1 NS NS

NS

RF, reduction factor expressed by decimal logarithms (log10 RF ¼ log10 pre-value  log10 post-value, from artificially contaminated hands of 12e15 volunteers); NS, not significant. a 2-Propanol 60% v/v. b P-values were derived using Wilcoxon matched-pairs signed-ranks test where P (one-sided) < 0.1 was considered significant.

using the Wilcoxon matched-pairs signed-rank test. If the difference is significant [P (onesided) < 0.1], the product is not acceptable.15 In this study, we used E. coli DSM No. 11250 (German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany) as the test organism, which was preserved by freezing according to EN 12353.17 In order to prevent carry-over inhibition, the following mixtures of neutraliser agents were used in sampling fluids and diluents for the assessment of post-values: (i) polysorbate 80 (30 mL/L), lecithin (30 g/L), and sodium thiosulphate (5 g/L) for alcohol-based hand gels produced in Brazil, and 70% ethyl alcohol; (ii) polysorbate 80 (30 mL/L), saponin (30 g/L), histidine (1 g/L), and cysteine (1 g/L) for Sterillium and Sterillium Gel; (iii) polysorbate 80 (30 mL/L), saponin (30 g/L), histidine (1 g/L), cysteine (1 g/L), and 0.3 lecithin (3 g/L) for Spitaderm. The control and validation of neutraliser agents was performed by the dilution-neutralisation method.18

Results The antimicrobial efficacy of the alcohol-based hand gels and rinses according to the EN 1500 assay is

shown in Table I. The majority (83%, 10 of 12) of alcohol-based hand gels produced in Brazil were approved by EN 1500 within 60 s. They reduced from 3.71 log10 units (Sanigel) to 4.62 log10 units (Hand Gel) of the transient bacterial flora (E. coli) applied to the hands. Solumax Solugel and WBL-50 Gel failed by EN 1500 because their log RF values (4.01 and 2.41) differed significantly from those of the reference alcohol (4.42 and 4.15). Sterillium Gel (log RF, 4.73), 70% ethyl alcohol (log RF: 3.99), Sterillium (log RF: 4.98), and Spitaderm (log RF: 4.67) passed the EN 1500 within 60 s. The log mean and standard deviation RF of the reference alcohol (2-propanol 60% v/v) in the 16 experiments performed was 4.16  0.18. The log RF values of Sanigel (3.71) and 70% ethyl alcohol (3.99) were the same as for the reference alcohol (Table I). The neutraliser agents showed no toxicity to the test organism (data not shown). The control and validation of neutraliser agents used in this study showed that there was no carry-over inhibition in the recovery of the test organism from fingertips after treatment with alcohol-based hand rubs.

222

Discussion In Brazil, the agents most used for hand hygiene in hospital practice include plain liquid soap for hand washing, antimicrobial soap containing either 2e4% chlorhexidine digluconate or 10% povidone-iodine (1% active iodine) for hygienic handwash, and 70% w/w ethyl alcohol for hygienic hand rub.4,19 The alcohol-based hand gel has only recently been introduced into Brazilian hospitals.20 However, there has been no systematic study on the antimicrobial efficacy of these products in Brazil. To our knowledge, this is the first study that compares the antimicrobial activity of the main alcohol-based hand gels produced in Brazil with that of the 2-propanol (isopropyl alcohol) 60% v/v that is the reference solution from the EN 1500. Our results showed that the majority of the tested alcohol-based hand gels were approved by the EN 1500 in the application time of 60 s. These findings may be used as an important argument to implement the use of alcohol gel in Brazilian hospitals. According to EN 1500, the mode of application of the product to be tested can be that indicated by the manufacturer. If instructions are lacking, they may receive the same treatment as the reference product (2-propanol 60% v/v), i.e. twice 3 mL for twice 30 s. Unfortunately, in our study, none of the alcohol-based hand gels produced in Brazil provides clear manufacturers’ recommendations for the mode of application. Thus, these gels were tested in the same way as the reference alcohol. By contrast, the modes of application of Sterillium Gel, Sterillium, and Spitaderm were clearly indicated on the product labels, which recommended to use at least 3 mL for at least 30 s. However, they were tested in the application time of 60 s, so that we could compare their antimicrobial efficacy with that of the alcohol-based hand gels produced in Brazil. One limitation in our study was that the application time of 60 s may not represent the true practice conditions of the products tested. In fact, observational studies have demonstrated that the median time taken for hand hygiene varies from 6.6 to 24 s, i.e. much less than the time of 60 s used in our study.2 However, we believe that the alcoholbased hand gels approved by EN 1500 in our study may reach a satisfactory effectiveness in healthcare settings, because in the experimental conditions of our study, they reduced about 99.99% of the transient bacterial flora on the hands. The value of relative reductions, e.g. 90% (1 log10), 99% (2 log10), 99.9% (3 log10), or 99.99 (4 log10) in the viable microbial counts on hands of healthcare personnel that are required to

M. Guilhermetti et al. prevent cross-transmission of nosocomial pathogens remains unknown.1,2,21,22 On the other hand, the statistically significant differences found in laboratory hand-hygiene experiments may not always be associated with different biological or clinical effects.21 Despite the application time of 60 s, the results obtained in our study were somewhat surprising, because a similar study performed in Europe showed that of 10 alcohol-based hand gels tested, none was approved by EN 1500 within 30 s.23 The contrast between these results can be explained, among other factors, by the type and concentration of the alcohol present in the tested formulations, and by the time of application and volume of the products used in hand antisepsis. Whether the alcohol-based hand gels produced in Brazil meet the efficacy criteria of EN 1500 in an application time of 30 s is a question that requires further studies. The antimicrobial activity of the alcoholic formulations in the gel form is usually lower than that of the liquid preparations.23e25 This is because, to increase viscosity, the gels frequently contain ingredients such as polyacrylic acid (a thickener) and polyamine (a neutraliser) that limit to some extent the amount of alcohol that can be incorporated into the product.24 The thickener system may hinder the release of the alcohol, reducing the efficacy of the product.26 Thus, to compensate for this lower antimicrobial activity, ethanol-based hand gels should contain at least 80% v/v of ethyl alcohol in their formulation.23,26 In our study, most (66%, 8 of 12) of the alcohol-based hand gels had a concentration of ethyl alcohol of 70% w/w, which approximates a concentration of 80% v/v.27 As expected and described in previous studies, in our study the alcohol-based hand rubs manufactured in Europe (Sterillium, Spitaderm, and Sterillium Gel) were approved by EN 1500.9,27 The best was Sterillium, which, in the application time of 60 s, reduced the population of E. coli on the hands by about 1 log10 (i.e. 90%) more than the reference alcohol (2-propanol). Our study also demonstrated that the alcoholbased hand gels approved by EN 1500 showed an antimicrobial efficacy similar to that of 70% w/w ethyl alcohol. These findings confirm and complement a previous study in our laboratory, in which we demonstrated that three alcohol-based hand gels produced in Brazil were as effective as the traditional ethyl alcohol 70% w/w in removing clinical isolates of meticillin-resistant Staphylococcus aureus, Serratia marcescens and Candida

Antimicrobial efficacy of alcohol gel albicans from heavily contaminated hands of human volunteers.14 During the execution of the experiments, we observed that some of the alcohol-based hand gels left residues on the hands after use, which certainly could influence their acceptability to healthcare workers. Although acceptability is considered a property of equal or even greater importance than antimicrobial efficacy, acceptability was not evaluated in the present study.28 Further studies are necessary to investigate this aspect. In Brazil, in order for manufacturers of alcoholbased hand gels to sell their products in healthcare settings, they must register with the Ministry of Health. In this case, among other technical requirements, the product must show in-vitro antibacterial efficacy against one of the following test organisms: S. aureus ATCC 6538 (American Type Culture Collection, Manassas, VA, USA), E. coli ATCC 11229, Pseudomonas aeruginosa ATCC 15442 or Salmonella choleraesuis ATCC 10708. The technique used is the agar cup-plate method.29 The study of the efficacy of the alcohol-based preparations used for hand antisepsis simulating practical conditions of use, i.e. tests in vivo, is hindered in Brazil because there is no official standardised method for evaluating the antimicrobial efficacy of these products. Therefore, in our study, we used as the experimental model the methodology described in EN 1500, which is adopted officially in the European Community as a standard test for hygienic hand rub.30 We believe that in countries that do not have officially sanctioned methods to evaluate alcoholic preparations ‘in vivo’, studies such as the present one, or similar studies, are necessary because the commercialisation of the new alcohol-based preparations in gel form can be recommended for use in hospitals only if they show antimicrobial efficacy at least similar to that of the alcohol-based liquid preparations, including the traditional ethyl alcohol 70% w/w, which have proven antimicrobial efficacy and therefore have been used for several decades for hand antisepsis in healthcare settings.2,4,31e33 In conclusion, the results obtained in the present study demonstrated the antimicrobial efficacy of most of the alcohol-based hand gels produced in Brazil for hand hygiene of healthcare workers. We hope that these data can contribute toward implementing the use of alcohol-based hand gels in Brazilian hospitals.

Acknowledgements We thank M.L. Rotter for supplying the strain of E. coli DSM 11250. Sterillium and Sterillium Gel

223 were provided by Bode Chemie GmbH, Hamburg, Germany. Spitaderm was provided by Profila ´tica Produtos Odonto Me ´dico Hospitalares Ltda., Curitiba, PR, Brazil. We also thank the volunteers for their cooperation in this study, and J.W. Reid for revising the English text. Conflict of interest statement None declared. Funding source This study was supported by the PROAP/CAPES and by the Conselho Nacional de Desenvolvimento Cientı´fico e Tecnolo ´gico-Brazil (MCT/ CNPq Processo 480556/2008-3).

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