Methods to evaluate the microbicidal activities of hand-rub and hand-wash agents

Evolving the EN 1500 test method for alcohol-based hand rub closer to clinical reality by reducing the organic load on hands and enabling product to be applied to dry hands

BACKGROUND

The methods currently used in Europe and North America to evaluate the bactericidal efficacy of hand hygiene products have some limitations, e.g., in the selection of test organisms or the method of contamination, and none of the methods allows prediction of actual clinical efficacy. WHO has therefore proposed to develop methods that better reflect typical clinical reality.

METHODS

In a first experiment, we investigated two contamination methods (immersion according to EN 1500 and low-volume according to ASTM E2755) with the EN 1500 test organism Escherichia coli and using 60% v/v iso-propanol. The second experiment was for comparison of the two contamination methods with Enterococcus faecalis. Finally, the two test organisms were compared using the low-volume contamination method. Data within each experiment was statistically compared using the Wilcoxon test for paired samples and data from all experiments were combined and fit to linear mixed effects models.

RESULTS

Mixed-effects analysis confirmed that the test organism and contamination method both impacted the pre-values and all three of these were factors that influenced log₁₀ reductions. Higher pre-values resulted in significantly higher log₁₀ reductions, immersion contributed to significantly higher log₁₀ reductions, and E. coli affected significantly lower log₁₀ reductions.

CONCLUSION

An efficacy evaluation against E. faecalis with a low-volume contamination method could be considered as an alternative to the EN 1500 standard. This could help improve the clinical relevance of the test method with including a Gram-positive organism and reducing soil load which allows a product application closer to reality.

Effect of Long-Term Use of Alcohol-Containing Handwashing Gels on the Biofilm-Forming Capacity of Staphylococcus epidermidis

The spread of coronavirus disease 2019 (COVID-19) has promoted the use of hand sanitizers among the general population as recommended by health authorities. Alcohols, which are used in many hand sanitizers, have been shown to promotes the formation of biofilms by certain bacteria and to increase bacterial resistance to disinfection. We investigated the effect of continued use of alcohol-based gel hand sanitizer on biofilm formation by the Staphylococcus epidermidis resident strain isolated from the hands of health science students. Hand microbes were counted before and after handwashing, and the ability to produce biofilms was investigated. We found that 179 (84.8%) strains of S. epidermidis isolated from hands had the ability to form biofilm (biofilm-positive strains) in an alcohol-free culture medium. Furthermore, the presence of alcohol in the culture medium induced biofilm formation in 13 (40.6%) of the biofilm-negative strains and increased biofilm production in 111 (76.6%) strains, which were classified as low-grade biofilm-producing. Based on our findings, there is no clear evidence that the continued use of alcohol-based gels results in the selection of strains with the capacity to form biofilms. However, other disinfectant formulations that are more commonly used in clinical settings, such as alcohol-based hand-rub solutions, should be tested for their long-term effects.

In vivo efficacy of alcohol based hand rubs against noroviruses: A novel standardized European test method simulating practical conditions

BACKGROUND

Non-enveloped viruses are particularly resistant to disinfectants, so to prevent and control the spread of virus infections, disinfectants with proven virucidal activity must be used. However, a test such as EN 1500, which uses an internal standard as reference treatment for determining the bactericidal efficacy of hand rubs, is still lacking. We aimed to establish a European standard for testing the in vivo efficacy of hand rubs against non-enveloped viruses.

METHOD

First, concentration and mode of application of ethanol as reference were determined. Afterwards, the efficacies of two commonly used hand rubs were compared to this reference. Hands of volunteers were contaminated with the murine norovirus strain S99.

RESULTS

70% wt/wt ethanol (2 x 3 mL in 2 x 30 seconds) was defined as internal reference treatment. The commercial ethanol based hand rub could significantly reduce the titre of norovirus in 30 seconds whereas a rub based on ethanol and propan-2-ol was significantly less effective compared to the reference.

CONCLUSION

We have established a possible standard for testing the in vivo efficacy of hand rubs against non-enveloped viruses using murine norovirus, a low contamination volume technique and ethanol as internal reference. Nevertheless our findings have to be confirmed in European ring trials.

Non-Alcohol Hand Sanitiser Gels with Mandelic Acid and Essential Oils

Antimicrobial hand gels have become extremely popular in recent years due to the COVID-19 pandemic. Frequent use of hand sanitising gel can lead to dryness and irritation of the skin. This work focuses on the preparation of antimicrobial acrylic acid (Carbomer)-based gels enhanced by non-traditional compounds-mandelic acid and essential oils-as a substitute for irritating ethanol. Physicochemical properties (pH and viscosity), stability and sensory attributes of the prepared gels were investigated. Antimicrobial activity against representative Gram-positive and Gram-negative bacteria and yeasts was determined. The prepared gels with mandelic acid and essential oil (cinnamon, clove, lemon, and thyme) proved to have antimicrobial activity and even better organoleptic properties than commercial ethanol-based antimicrobial gel. Further, results confirmed that the addition of mandelic acid had a desirable effect on gel properties (antimicrobial, consistency, stability). It has been shown that the essential oil/mandelic acid combination can be a dermatologically beneficial hand sanitiser compared to commercial products. Thus, the produced gels can be used as a natural alternative to alcohol-based daily hand hygiene sanitisers.

Comparative antimicrobial efficacy of 4 surgical hand-preparation procedures prior to application of an alcohol-based hand rub in veterinary students

OBJECTIVE

To determine the influence of skin preparations before application of an alcohol-based hand rub (ABHR) on bacterial counts before and after elective surgery.

STUDY DESIGN

Clinical prospective study.

SAMPLE POPULATION

Veterinary students (n = 103) performing ovariohysterectomies on 140 dogs.

METHODS

Participants were randomly assigned to 1 initial surgical preparation on the day of surgery: A - hand preparation with medicated solution (4% w/v chlorhexidine bigluconate followed by an ABHR; B - application of a medication solution (benzalkonium chloride 0.1%-1% and polymeric biguanide hydrochloride 0.01%-0.1%) followed by an ABHR; C - nonmedicated pH-neutral soap hand wash followed by ABHR, and D - direct application of an ABHR. Samples were taken by pressing the distal finger tips to an agar plate before the hand preparation, after the hand preparation (n = 3), after ABHR application, and 120 minutes later. Colony-forming units (CFUs) for samples were determined. Total log CFU and CFU log10 reduction were calculated and used for comparison with P < .05.

RESULTS

Two hours after surgery commenced, the participants of groups that performed a hand preparation had lower total CFUs than those that did not perform a hand preparation (P = .001). In particular, the number of CFUs was lower when ABHR was performed after application of pHN compared to direct ABHR (P = .001).

CONCLUSION

In this population, performing a hand preparation with pHN prior to applying an ABHR had better antimicrobial effect for the duration of surgery than not performing a hand preparation.

CLINICAL SIGNIFICANCE

Surgeons should wash their hands prior to ABHR before starting their first surgery of the day, even when hands appear clean.

Assessment of Bacterial Transfer From Patient to Chiropractor During Spinal Manipulation

Objective

This study aimed to measure the amount of bacteria that may be transferred from patient to chiropractor during spinal manipulation and the efficacy of decontaminants commonly used by chiropractic practitioners.

Methods

We chose Kwazulu-Natal, South Africa as the location, which is an area with an increased burden of immunocompromised patients resulting from HIV and tuberculosis. In this region, we obtained samples from 40 chiropractors' hands before and after spinal manipulation. Viable counts of colony-forming units were enumerated to verify the presence of bacteria. A modified Kirby-Bauer technique was used to ascertain the efficacy of the top 5 decontaminants used by chiropractors in this area against the bacteria isolated from their hands.

Results

Both normal microflora and potentially pathogenic bacteria were found. These included Staphylococcus spp., Micrococcus spp., Bacillus spp., Pseudomonas spp., Escherichia coli, Streptococcus spp., and Staphylococcus aureus. Higher bacterial counts were found on chiropractors' hands after patient contact for spinal manipulation, which are similar to findings from studies of other healthcare personnel. The 5 commonly used disinfectants tested in a lab setting were not as effective against bacterial samples when compared with an antimicrobial pharmaceutical medication.

Conclusions

The net transfer of bacteria to chiropractors' hands from the patient to the practitioner during spinal manipulation included primary and opportunistic pathogens. The detergents commonly used by chiropractors in this region showed varying efficacies against microbial growth when tested in vitro.

Phi 6 recovery from inoculated fingerpads based on elution buffer and methodology

Phi 6 (Φ6) bacteriophage is a proposed surrogate to study pathogenic enveloped viruses including SARS-CoV-2-the causative agent of COVID-19-based on structural similarities, BSL-1 status, and ease of use. To determine the role of virus-contaminated hands in disease transmission, an enhanced understanding of buffer and method performance for Φ6 recovery needs to be determined. Four buffer types and three methodologies were investigated for the recovery of Φ6 from human fingerpads over a 30 min duration. Phosphate buffered saline (PBS), PBS + 0.1 % Tween, 0.1 M glycine + 3% beef extract, and viral transport medium were evaluated as buffers for recovery of Φ6 via a dish, modified glove juice, and vigorous swabbing method. Φ6 concentrations on fingerpads were determined at 0-, 5-, 10-, and 30-min post-inoculation. While there were observed differences in virus recovery across buffer and method types depending on the time point, log PFU recovery based on buffer type or methodology was not significantly different at any time point (P > 0.05). The results presented in this study will allow for future work on Φ6 persistence, transfer between hands and surfaces, and efficacy of hand hygiene methods to be performed using a well-characterized and validated recovery method.

Alcohol-Based Hand Sanitizers in COVID-19 Prevention: A Multidimensional Perspective

The global use of alcohol-based hand sanitizers (ABHS) as an important means of controlling the transmission of infectious disease has increased significantly as governments and public health agencies across the world advocated hand hygiene as a preventative measure during the COVID-19 pandemic. Although the performance of these products is most commonly defined as a function of their alcohol concentration, they are multifaceted products in which an interplay of several factors is important in determining efficacy. This paper discusses the interplay between ABHS input (formulation) factors and output (product performance) factors in the context of a multidimensional perspective using a novel representative paradigm. In the model, represented in the form of a three-dimensional tetrahedron, each of the faces represents inputs in the manufacturing of the ABHS product, which are the type and amount of alcohol, the inactive ingredients, the formulation and the manufacturing practices. The four corners of the tetrahedron represent the product performance factors which include product efficacy, sensory characteristics, usage and compliance and product safety. The multidimensional approach to the formulation and evaluation of ABHS shows that several factors contribute to the effectiveness and utility of these products. The paradigm provides a useful framework for manufacturers of ABHS and related healthcare products.

Fomite Transmission, Physicochemical Origin of Virus-Surface Interactions, and Disinfection Strategies for Enveloped Viruses with Applications to SARS-CoV-2

Inanimate objects or surfaces contaminated with infectious agents, referred to as fomites, play an important role in the spread of viruses, including SARS-CoV-2, the virus responsible for the COVID-19 pandemic. The long persistence of viruses (hours to days) on surfaces calls for an urgent need for effective surface disinfection strategies to intercept virus transmission and the spread of diseases. Elucidating the physicochemical processes and surface science underlying the adsorption and transfer of virus between surfaces, as well as their inactivation, is important for understanding how diseases are transmitted and for developing effective intervention strategies. This review summarizes the current knowledge and underlying physicochemical processes of virus transmission, in particular via fomites, and common disinfection approaches. Gaps in knowledge and the areas in need of further research are also identified. The review focuses on SARS-CoV-2, but discussion of related viruses is included to provide a more comprehensive review given that much remains unknown about SARS-CoV-2. Our aim is that this review will provide a broad survey of the issues involved in fomite transmission and intervention to a wide range of readers to better enable them to take on the open research challenges.

Efficacies of the original and modified World Health Organization-recommended hand-rub formulations

The World Health Organization (WHO) hand-rub formulations have been in use around the world for at least the past 10 years. The advent of coronavirus disease 2019 (COVID-19) has further enhanced their use. We reviewed published efficacy data for the original and modified formulations. Only efficacy data according to the European Norms (EN) were found. The bactericidal efficacy of the original formulations was, under practical conditions, partly insufficient (EN 1500, only effective in 60 s; EN 12791, efficacy too low in 5 min). The first modification with higher alcohol concentrations improves their efficacy as hygienic hand rub (effective in 30 s). The second (0.725% glycerol) and third (0.5% glycerol) modification improves their efficacy for surgical hand preparation (effective in 5 and 3 min). The original and second modified formulations were tested and demonstrate activity against enveloped viruses including severe acute resiratory syndrome coronavirus 2 (SARS-CoV-2) in 30 s. The ethanol-based formulation is also active against some non-enveloped test viruses in 60 s (suspension tests, EN 14476). In-vivo data on the formulations would provide a more reliable result on the virucidal efficacy on contaminated hands but are currently not available. Nevertheless, the most recent modifications should be adopted for use in healthcare.

In Vivo Comparison of Chlorine-Based Antiseptics versus Alcohol Antiseptic for Surgical Hand Antisepsis

Despite being commonly used as effective preparation for surgical hand antisepsis, alcohol solutions have major drawbacks, such as drying effect, emergence of hand eczema, and other diseases. This study aimed to demonstrate the effectiveness of sodium hypochlorite (NaOCl) and hydrogen peroxide (H₂O₂) as antiseptic in comparison to single sodium hypochlorite and 70% ethanol. In 5-day tests, the effects of 3 antiseptics were established according to standard test methods. The antiseptics were applied to the hands of 82 volunteers, and samples of bacteria were collected on days 1 and 5, immediately after drying and 6 hours later after antiseptic application. Student's t test and ANOVA were applied in a statistical study. The NaOCl with H₂O₂ composition demonstrated noninferiority to both sodium hypochlorite only and alcohol products and superiority to these antiseptics on day 5 (P < 0.05 at a significance level of 5% for each comparative trial in this day) at equivalence margin of 20%. The effectiveness of the NaOCl plus H₂O₂ composition as an antiseptic was explained by the formation of singlet oxygen in the system. Together, these data suggest that NaOCl and H₂O₂ may be an effective hand antisepsis that avoids the drawbacks seen with alcohol solutions.

Surgical hand hygiene and febrile urinary tract infections in endourological surgery: a single-centre prospective cohort study

Surgical hand hygiene reduces the risk of surgical site infections (SSIs). SSIs are not considered an issue in endourological surgery, whereas febrile urinary tract infections (f-UTIs) and urological sepsis are becoming problematic. We wondered whether surgical hand hygiene is necessary for endourological surgery. Therefore, we aimed to evaluate the influence of surgical hand hygiene on f-UTI onset in endourological surgery by comparing procedures in which surgical hand hygiene with double gloving was used with those in which regular hand hygiene with double gloving was used between April 2016 and July 2020. In this prospective cohort study of 477 patients who underwent endourological surgeries, surgeons in the surgical hand hygiene and regular hygiene groups performed surgery on 259 and 218 patients, respectively. There was no significant difference in patient background, and multivariate analyses revealed no significant differences in f-UTI onset (odds ratio, 0.87; p = 0.74) between the two groups. In conclusion, regular hand hygiene with double gloving may be considered an alternative to surgical hand hygiene to prevent endourological f-UTIs, which could alter operational protocols for endourological surgery. Further studies are needed to validate our findings.

Antiseptic efficacies of waterless hand rub, chlorhexidine scrub, and povidone-iodine scrub in surgical settings: a meta-analysis of randomized controlled trials

BACKGROUND

Presurgical hand washing is crucial for preventing surgical site infections (SSIs). Chlorhexidine gluconate (CHG) and povidone-iodine (PI) products have been conventionally used as hand scrubs for presurgical hand preparation. However, waterless hand rub (WHR) products have been developed for operating room staff.

AIM

The aim of this study was to conduct a systematic review and meta-analysis to compare the antiseptic efficacies of WHR, CHG, and PI in surgical settings.

METHODS

PubMed, Embase, and Cochrane Library databases as well as the ClinicalTrials.gov registry were searched for studies published before October 2018. Randomized controlled trials (RCTs) comparing the clinical outcomes of the use of WHRs, CHG, or PI for presurgical hand washing were included. A random effects model was used for meta-analysis. Colony-forming unit (cfu) counts, SSI rates, and preference and compliance were determined to measure efficacies.

FINDINGS

Eleven RCTs involving 5135 participants were included. Residual cfu counts were significantly lower in the WHR and CHG groups than in the PI group. The differences in cfu counts between the WHR and CHG groups were non-significant. No significant differences were observed in the SSI rates between the WHR and traditional hand scrub groups. Moreover, WHRs were considered most favourable and were associated with higher compliance rates than the other products.

CONCLUSION

WHRs and CHG exhibited higher antiseptic efficacies than PI. However, additional studies with consistent outcome measurements and accurate grouping are required to obtain comprehensive results. Moreover, preference, compliance, and the cost determine the selection of hand wash products.

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.

Topical Antimicrobial Treatments Can Elicit Shifts to Resident Skin Bacterial Communities and Reduce Colonization by Staphylococcus aureus Competitors

The skin microbiome is a complex ecosystem with important implications for cutaneous health and disease. Topical antibiotics and antiseptics are often employed to preserve the balance of this population and inhibit colonization by more pathogenic bacteria. However, despite their widespread use, the impact of these interventions on broader microbial communities remains poorly understood. Here, we report the longitudinal effects of topical antibiotics and antiseptics on skin bacterial communities and their role in Staphylococcus aureus colonization resistance. In response to antibiotics, cutaneous populations exhibited an immediate shift in bacterial residents, an effect that persisted for multiple days posttreatment. By contrast, antiseptics elicited only minor changes to skin bacterial populations, with few changes to the underlying microbiota. While variable in scope, both antibiotics and antiseptics were found to decrease colonization by commensal Staphylococcus spp. by sequencing- and culture-based methods, an effect which was highly dependent on baseline levels of Staphylococcus Because Staphylococcus residents have been shown to compete with the skin pathogen S. aureus, we also tested whether treatment could influence S. aureus levels at the skin surface. We found that treated mice were more susceptible to exogenous association with S. aureus and that precolonization with the same Staphylococcus residents that were previously disrupted by treatment reduced S. aureus levels by over 100-fold. In all, the results of this study indicate that antimicrobial drugs can alter skin bacterial residents and that these alterations can have critical implications for cutaneous host defense.

Comparison of an alcohol-based hand sanitation product with a traditional chlorhexidine hand scrub technique for hand hygiene preparation in an equine hospital

AIMS

To investigate the efficacy of an alcohol gel-based hand antisepsis protocol compared with a traditional chlorhexidine-based protocol under conditions of routine clinical contamination, and following heavy faecal contamination.

METHODS

Twelve adult participants were recruited and on four separate days completed a hand sanitation protocol using a chlorhexidine scrub or an alcohol-based gel, with hands that were grossly clean but contaminated or with faecal contamination. Bacterial samples were obtained from participants' hands before sanitation, immediately after and then 2 hours later. All samples were cultured on blood and MacConkey agar and bacterial colonies counted after 48 hours.

RESULTS

for clean contaminated hands, the percentage reduction in bacterial colonies on blood agar immediately after hand sanitation was similar for both protocols (p=0.3), but was greater for the alcohol gel than chlorhexidine after 2 hours (p=0.005). For hands with faecal contamination, the percentage reduction in bacterial colonies on blood agar was similar for both protocols immediately and 2 hours after sanitation (p>0.2), but positive cultures were obtained on blood agar from samples collected after both protocols, for almost all participants.

CONCLUSIONS

The results indicate equivalent efficacy of the alcohol-based gel and the pre-surgical chlorhexidine protocol.

CLINICAL RELEVANCE

The alcohol-based gel protocol is an effective hand asepsis technique for grossly clean contaminated hands and those following faecal contamination, with comparable efficacy to chlorhexidine based scrub.

Preoperative Hand Decontamination in Ophthalmic Surgery: A Comparison of the Removal of Bacteria from Surgeons' Hands by Routine Antimicrobial Scrub versus an Alcoholic Hand Rub

PURPOSE

The goal of this experiment was to evaluate and compare the antimicrobial efficacy of routine preoperative hand washing using commercial medicated sponge brushes versus an alcoholic hand rub, by comparing bacterial growth on ophthalmic surgeons' hands after application of each of these methods.

METHODS

Twenty ophthalmic surgeons were recruited at the Hadassah-Hebrew University Medical Center in Jerusalem, Israel. Samples were collected twice from the hands of each surgeon after hand decontamination using two different protocols during routine surgical practice. The routine preparation consisted of a 3-minute surgical scrub using commercial brush-sponges incorporating either 4% chlorhexidine gluconate (CHG) or 1% povidone-iodine (PVP-I) formulations with detergent, followed by drying the hands with a sterile towel, while the 70% ethanol solution was applied for 60-seconds and allowed to air dry. Half of the group was randomly assigned to provide samples first after the routine method and the alcoholic solution a week later, and the other half of the group was sampled in the reverse order. Viable counts of bacteria were evaluated using a modified glove juice method. Bacterial colonies were enumerated after incubation for 24 hours and expressed as colony forming units (CFU)/mL for each pair of hands.

RESULTS

Geometric mean counts were 1310 and 39 CFU/mL, in the routine and alcohol rub groups, respectively, representing a mean log₁₀ reduction in 1.53. The difference between the paired bacterial counts for the routine versus the alcohol rub was statistically significant (p < 0.0001). There was no statistically significant difference between log₁₀ reductions for CHG and PVP-I (p = 0.97).

CONCLUSIONS

This study provides evidence that an alcohol rub protocol is more effective in reducing bacterial counts on hands than routine surgical hand preparation with PVP-I and CHG in a population of practicing ophthalmic surgeons in the operative clinical setting. Thus, it provides a safe alternative as a preoperative hand disinfection method.

Assessing the Likelihood of Hand-to-Hand Cross-Transmission of Bacteria: An Experimental Study

BACKGROUND Although the hands of healthcare workers (HCWs) are implicated in most episodes of healthcare-associated infections, the correlation between hand contamination and the likelihood of cross-transmission remains unknown. METHODS We conducted a laboratory-based study involving pairs of HCWs. The hands of a HCW (transmitter) were contaminated with Escherichia coli ATCC 10536 before holding hands with another HCW (host) for 1 minute. Meanwhile, the unheld hand of the transmitter was sampled. Afterward, the host's held hand was also sampled. Each experiment consisted of 4 trials with increasing concentrations of E. coli (103-106 colony-forming units [cfu]/mL). The primary outcome was the likelihood of transmission of at least 1 cfu from transmitter to host. We used a mixed logistic regression model with a random effect on the subject to assess the association between transmission and bacterial count on the transmitter's hands. RESULTS In total, 6 HCWs performed 30 experiments and 120 trials. The bacterial counts recovered from host hands were directly associated with the bacterial counts on transmitter hands (P1 and ≤3 log10 cfu compared to ≤1 log10. When transmitter contamination was <1 log10 cfu, no cross-transmission was detected. CONCLUSION There is a direct relationship between the bacterial burden on HCWs hands and the likelihood of cross-transmission. Under the described conditions, at least 1 log10 cfu must be present on HCW hands to be potentially transmitted. Further studies are needed at the low contamination range. Infect Control Hosp Epidemiol 2017;38:553-558.

Fluorescence assay for evaluating microbicidal activity of hand antiseptics

We developed a fluorescent β-d-glucuronidase activity (BGA)-based assay for detecting and quantifying Escherichia coli in samples to assess the biocide efficacy of hand antiseptics. The fluorescence level is proportional to the number of viable E. coli organisms present. We compared our assay results to those of the E. coli plate count method specified by the European standard for testing hygienic hand rub disinfectant products (EN1500). The plate count method requires excessive handling and materials and is not valid if the number of organisms per plate is too low or high for counting in many of the samples. We optimized the fluorescent assay based on the cleavage of 4-methylumbelliferyl-β-d-glucuronide by adding 4-nitrophenyl-β-d-glucuronide, a nonfluorogenic BGA substrate, to induce glucuronidase activity and reduce assay time. Furthermore, our method can be automated and eliminates the need for multiple dilutions. Fluorescence was temporally monitored, and the time required to reach a specific value of fluorescence was correlated with the initial number of viable E. coli organisms on the samples. There was a positive correlation (P < 0.05) with a high correlation coefficient (R(2) = 0.82) between the E. coli counts by plate count and fluorescence methods. Reported effects in fluorescent BGA were compared to the EN1500 plate count method with five hand disinfectants. We found our method more advantageous, because it was as sensitive as the EN1500 method, requires less time to complete, and is less expensive and less laborious than conventional plating techniques.

Use of 70% alcohol for the routine removal of microbial hard surface bioburden in life science cleanrooms

ABSTRACT 

Alcohol-based disinfectants are used for the removal of microbial hard surface bioburden in Life science Cleanrooms. Evidence for using formulations containing 70% alcohol has been lost over time but probably originates from historical observations of the activity of 60–70% alcohol. Tradition is no longer adequate to inform contemporary cleaning practice. We evaluated the efficacy of ethanol, isopropanol and trade-specific denatured alcohol 7 against vegetative Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Enterococcus hirae using standardized European Suspension and Hard Surface tests. All three alcohols were effective at lower concentrations than the 70% standard. This constitutes the first evaluation of disinfectant formulations containing ≤70% alcohol using standard methodology. The utility of trade-specific denatured alcohol #7 and evidence-based cleanroom practice warrant further validation.

The relative influences of product volume, delivery format and alcohol concentration on dry-time and efficacy of alcohol-based hand rubs

Background

Alcohol-based hand rubs (ABHR) range in alcohol concentration from 60-95% and are available in a variety of delivery formats, such as rinses, gels, and foams. Recent studies suggest that some ABHR foams dry too slowly, thereby encouraging the use of inadequate volumes. This study investigates the influence of product volume, delivery format, and alcohol concentration on dry-time and antimicrobial efficacy of ABHR foams, gels and rinses.

Methods

ABHR dry-times were measured using volunteers to determine the influences of product volume, delivery format, and alcohol concentration. ABHR efficacies were evaluated according to the European Standard for Hygienic Hand Disinfection (EN 1500) using 3-mL application volumes rubbed for 30 s, and additionally, using volumes of the products determined to rub dry in 30 s.

Results

Volumes of six ABHR determined to rub dry in 30 s ranged from 1.7 mL to 2.1 mL, and the rate of drying varied significantly between products. ABHR dry-times increased linearly with application volume and decreased linearly with increasing alcohol concentration, but were not significantly influenced by product format. An ABHR foam (70% EtOH), rinse (80% EtOH), and gel (90% EtOH) each met EN 1500 efficacy requirements when tested at a volume of 3 mL, but failed when tested at volumes that dried in 30 s.

Conclusions

Application volume is the primary driver of ABHR dry-time and efficacy, whereas delivery format does not significantly influence either. Although products with greater alcohol concentration dry more quickly, volumes required to meet EN 1500 can take longer than 30 s to dry, even when alcohol concentration is as high as 90%. Future studies are needed to better understand application volumes actually used by healthcare workers in practice, and to understand the clinical efficacy of ABHR at such volumes.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-511) contains supplementary material, which is available to authorized users.

New method for assessing hand disinfection shows that pre-operative alcohol/chlorhexidine rub is as effective as a traditional surgical scrub

BACKGROUND

Several studies have shown that rubbing hands with an alcohol/chlorhexidine solution provides equivalent microbial decontamination to a conventional surgical scrub using aqueous chlorhexidine. However, the authors believe that these studies have methodological flaws that limit their applicability to the operating theatre environment. As such, a method was developed to compare products in an everyday operating theatre environment using working operating theatre personnel.

AIM

To determine whether or not an alcohol/chlorhexidine rub is as efficacious as a traditional surgical scrub using a novel method.

METHODS

Bacterial counts at baseline were collected from 20 anaesthetists using the glove juice method. Subsequently, with sequential exchange of sterile gloves, one hand underwent a 3-min scrub using 4% aqueous chlorhexidine, and the other hand underwent a 60-s rub with a 70% isopropyl alcohol/0.5% chlorhexidine solution. The residual bacterial count was collected for each hand after 30 min using the glove juice method. These counts were converted to log10 values to compare the baseline counts of right and left hands, and efficacy between the treatment groups.

FINDINGS

Mean [± standard deviation (SD)] bacterial counts at baseline were (log10) 4.42 ± 0.81 for left hands and 4.64 ± 0.60 for right hands (P > 0.05). The mean (± SD) reduction from baseline was (log10) 1.45 ± 0.50 for 4% chlorhexidine and 2.01 ± 0.98 for alcohol/chlorhexidine (P > 0.05).

CONCLUSION

An alcohol/chlorhexidine hand rub was found to be as efficacious as a traditional scrub after 30 min; this study differs from previous work as it was undertaken in a population of practising anaesthetists in their working environment. The McKenzie method allows baseline and study evaluations to be performed contemporaneously on the same individual. Each subject was his/her own control. This method offers a more clinically relevant way to compare disinfectant solutions than standard methods.

Evaluation with a focus on both the antimicrobial efficacy and cumulative skin irritation potential of chlorhexidine gluconate alcohol-containing preoperative skin preparations

BACKGROUND

Important characteristics for ideal skin preparations include long-lasting antimicrobial efficacy and low potential for skin irritation.

METHODS

A total of 55 healthy adult subjects were enrolled to evaluate the antimicrobial effects of 3 test formulations applied to inguinal, abdominal, and antecubital sites at post-treatment time points of 30 seconds, 72 hours, and 7 days. To investigate skin irritation potential, the 3 formulations were tested in a 21-day repeat-insult patch test conducted on the skin of the backs of 23 healthy subjects.

RESULTS

The mean log(10) reduction (MLR) at 7 days post-treatment produced by a 79% vol/vol ethanol containing 1% wt/vol chlorhexidine gluconate (1% CHG-EtOH) applied to abdominal sites was significantly superior to that produced by a 10% povidone-iodine solution (2.45 MLR vs 0.90 MLR; P < .05). The 1% CHG-EtOH and a 70% vol/vol isopropanol containing 2% wt/vol CHG (2% CHG-IPA) provided statistically equivalent persistence at 72 hours and 7 days post-treatment. The 1% CHG-EtOH had less skin irritation potential than the 2% CHG-IPA and the 10% povidone-iodine solution, although the differences were not statistically significant (P > .05).

CONCLUSION

Considering its persistent effect and low skin irritation potential, the 1% CHG-EtOH preparation is expected to perform well in surgical site preparation to reduce the risk of surgery- and catheter-related bloodstream infection.

A comparative clinical study focusing on the antimicrobial efficacies of chlorhexidine gluconate alcohol for patient skin preparations

Comparative efficacy study data showed that skin preparations formulated with more than 0.5% chlorhexidine gluconate (CHG) in alcohol produced significant reductions in microbial populations at the inguinal, abdominal, and antecubital sites at each sample time (P < .05) relative to baseline, and there were no significant differences statistically, including persistent effects within 24 hours (P > .05). It would be reasonable to expect that a 1% CHG-ethanol skin preparation (with >0.5% CHG in alcohol) could be chosen in Japan that would perform well and have promising potential for catheter preparation/maintenance preparation with consideration for recommendation of the Centers for Disease Control and Prevention's guideline issued in 2011.

Back to the future: rising to the Semmelweis challenge in hand hygiene

Hand hygiene is the single most important intervention for reducing healthcare associated infections and preventing the spread of antimicrobial resistance. This sentence begins most publications regarding hand hygiene in the medical literature. But why - as we mark 150 years since the publication of Ignaz Semmelweis' landmark monograph on the subject - do we continue to repeat it? One might be tempted to regard it as a truism. However, while tremendous progress has certainly been made in this field, a significant amount of work is yet to be done in both strengthening the evidence regarding the impact of hand hygiene and maximizing its implementation. Hand hygiene cannot yet be taken for granted. This article summarizes historical perspectives, dynamics of microbial colonization and efficacy of hand cleansing methods and agents, elements and impacts of successful hand hygiene promotion, as well as scale-up and sustainability. We also explore hand hygiene myths and current challenges such as monitoring, behavior change, patient participation and research priorities.

Quest for a realistic in vivo test method for antimicrobial hand-rub agents: introduction of a low-volume hand contamination procedure

A novel method has been developed for the evaluation of alcohol-based hand rubs (ABHR) that employs a hand contamination procedure that more closely simulates the in-use conditions of ABHR. Hands of human subjects were contaminated with 0.2 ml of a concentrated suspension of Serratia marcescens (ATCC 14756) to achieve baseline contamination between 8 and 9 log₁₀ CFU/hand while allowing product to be applied to dry hands with minimal soil load. Evaluation of 1.5 ml of an ABHR gel containing 62% ethanol produced log₁₀ reductions of 2.66 ± 0.96, 2.40 ± 0.50, 2.41 ± 0.61, and 2.33 ± 0.49 (means ± standard deviations) after 1, 3, 7, and 10 successive contamination/product application cycles. In a study comparing this low-volume contamination (LVC) method to ASTM E1174, product dry times were more realistic and log₁₀ reductions achieved by the ABHR were significantly greater when LVC was employed (P < 0.05). These results indicate that a novel low-volume hand contamination procedure, which more closely represents ABHR use conditions, provides more realistic estimates of in-use ABHR efficacies. Based on the LVC method, log₁₀ reductions produced by ABHR were strongly dependent on the test product application volume (P < 0.0001) but were not influenced by the alcohol concentration when it was within the range of 62 to 85% (P = 0.378).

Determination of antiseptic efficacy of rubs on the forearm and consequences for surgical hand disinfection

While hands are acknowledged to be the most important source of pathogens from the skin of the surgical team, the transmission of pathogens from the forearms may also be relevant. Preoperative hand disinfection is recommended, but evidence-based standards for the forearms are lacking. As neither the European standard EN 12791 nor the American guidelines ASTM 1115 are applicable to the forearms, a new test method based on the European standard EN 12791 and the German Society for Hygiene and Microbiology (DGHM) method for testing for the efficacy of skin antiseptics was developed to address the forearms. The antiseptic efficacy of a commercially available alcohol-based hand rub [76.7% (w/w) ethanol] was assessed on the upper arm after 15s, 2.5 min, and 30 min, and on the lower arm after 2.5 min, 30 min, and 3 h. On the upper arm, application of the product followed the DGHM standard procedure. On the forearm, the product was applied by the participants themselves with the right hand over the left forearm and vice versa as performed during preoperative hand disinfection. Sampling and culture were performed according to the DGHM method for skin antisepsis on the upper arm. Twenty-two volunteers were investigated. The efficacy of the antiseptic treatment on the forearm was not significantly lower than on the upper arm for any of the areas tested (P > 0.05). Reduction factors for all tested areas and times were quite similar, with confidence intervals ranging between 1.43 and 2.31 log₁₀. We suggest that an application time of 10s may be sufficient for the treatment of the forearm as part of preoperative hand disinfection, provided that an appropriate product is used.

Comparative evaluation of the hygienic efficacy of an ultra-rapid hand dryer vs conventional warm air hand dryers

Aims:

To compare an ultra-rapid hand dryer against warm air dryers, with regard to: (A) bacterial transfer after drying and (B) the impact on bacterial numbers of rubbing hands during dryer use.

Methods and Results:

The Airblade™ dryer (Dyson Ltd) uses two air ‘knives’ to strip water from still hands, whereas conventional dryers use warm air to evaporate moisture whilst hands are rubbed together. These approaches were compared using 14 volunteers; the Airblade™ and two types of warm air dryer. In study (A), hands were contaminated by handling meat and then washed in a standardized manner. After dryer use, fingers were pressed onto foil and transfer of residual bacteria enumerated. Transfers of 0–10⁷ CFU per five fingers were observed. For a drying time of 10 s, the Airblade™ led to significantly less bacterial transfer than the other dryers (P<0·05; range 0·0003–0·0015). When the latter were used for 30–35 s, the trend was for the Airblade to still perform better, but differences were not significant (P>0·05, range 0·1317–0·4099). In study (B), drying was performed ± hand rubbing. Contact plates enumerated bacteria transferred from palms, fingers and fingertips before and after drying. When keeping hands still, there was no statistical difference between dryers, and reduction in the numbers released was almost as high as with paper towels. Rubbing when using the warm air dryers inhibited an overall reduction in bacterial numbers on the skin (P < 0·05).

Conclusions:

Effective hand drying is important for reducing transfer of commensals or remaining contaminants to surfaces. Rubbing hands during warm air drying can counteract the reduction in bacterial numbers accrued during handwashing.

Significance and Impact of the Study:

The Airblade™ was superior to the warm air dryers for reducing bacterial transfer. Its short, 10 s drying time should encourage greater compliance with hand drying and thus help reduce the spread of infectious agents via hands.

Prevention and control of health care-associated infections through improved hand hygiene

Determined actions are required to address the burden due to health care-associated infections worldwide and improve patient safety. Improving hand hygiene among health care workers is an essential intervention to achieve these goals. The World Health Organization (WHO) First Global Patient Safety Challenge, Clean Care is Safer Care, pledged to tackle the problem of health care-associated infection at its launch in 2005 and has elaborated a comprehensive set of guidelines for use in both developed and developing countries worldwide. The final version of the WHO Guidelines on Hand Hygiene in Health Care was issued in March 2009 and includes recommendations on indications, techniques, and products for hand hygiene. In this review, we discuss the role of hands in the transmission of health care-associated infection, the benefits of improved compliance with hand hygiene, and the recommendations, implementation strategies and tools recommended by WHO. We also stress the need for action to increase the pace with which these recommendations are implemented in facilities across India.