Inactivation of feline calicivirus, a surrogate of norovirus (formerly Norwalk-like viruses), by different types of alcohol in vitro and in vivo

To disinfect or not to disinfect that is the question - Procedure when drawing blood for alcohol measurements in Denmark

Swabbing with ethanol to disinfect the skin before venipuncture does not bias measurements of blood ethanol, as previously suspected. International evidence-based theory may not always be successfully integrated into local practices, where old customs may remain. So how are the local protocols for swabbing in practice - if they even do swab? Not disinfecting may risk patient safety. We aim to put a focus on the venipuncture disinfection procedure in practice when measuring blood alcohol for clinical matters and if their procedure refers to a guideline. Specialized biomedical laboratory scientists (BLS) are typically responsible for the phlebotomy procedure in Denmark, thus questionnaires were sent to the relevant BLS in 2020 to map disinfection procedures in all Danish hospitals and affiliated blood draw clinics (n = 58). The response rate was 93% (54/58). We observed an inter-laboratory dissimilarity in swabbing procedures, when measuring blood alcohol: A quarter did not use any disinfectant (26%), while the remaining disinfected with ethanol 55%, isopropanol 13%, and 6% with ethanol/chlorhexidine. Of the five Danish regions, three had a regional guideline (3/5), otherwise the swabbing protocol was locally based. There was a regional difference in disinfecting or not (Chi2 p < 0,0001). Danish protocols do not always parallel international literature and international guidelines. Not applying disinfectant may jeopardize patient safety. Laboratories are encouraged to work with evidence-based practice or follow newest standardized international guidelines.

Higher Viral Stability and Ethanol Resistance of Avian Influenza A(H5N1) Virus on Human Skin

Evaluating the stability of highly pathogenic avian influenza viruses on human skin and measuring the effectiveness of disinfectants are crucial for preventing contact disease transmission. We constructed an evaluation model using autopsy skin samples and evaluated factors that affect the stability and disinfectant effectiveness for various subtypes. The survival time of the avian influenza A(H5N1) virus on plastic surfaces was ≈26 hours and on skin surfaces ≈4.5 hours, >2.5-fold longer than other subtypes. The effectiveness of a relatively low ethanol concentration (32%–36% wt/wt) against the H5N1 subtype was substantially reduced compared with other subtypes. Moreover, recombinant viruses with the neuraminidase gene of H5N1 survived longer on plastic and skin surfaces than other recombinant viruses and were resistant to ethanol. Our results imply that the H5N1 subtype poses a higher contact transmission risk because of its higher stability and ethanol resistance, which might depend on the neuraminidase protein.

Comparison of virucidal efficacy of sodium hypochlorite, chlorine dioxide, peracetic acid, and ethanol against hepatitis A virus by carrier and suspension tests

A carrier (stainless steel disc as a default carrier) testing method is very needed for use in the actual food-processing fields by following the standard guideline. Here, we aimed to compare the virucidal efficacy of four commercial liquid disinfectants, including sodium hypochlorite (NaOCl), chlorine dioxide (ClO₂), and peracetic acid (PAA) against hepatitis A virus (HAV) following the OECD guideline protocol based on the quantitative carrier testing method and compared carrier testing results with the suspension testing results. The OECD method specifies a test for establishing whether a chemical disinfectant or a microbicide has a virucidal activity on hard non-porous surfaces. The antiviral efficacy was evaluated by plaque assays, and disinfectants were considered effective if the virus reduction was greater than or equal to 3 log₁₀ (99.9% decrease) for carrier or 4 log₁₀ (99.99% decrease) for suspension tests. Results indicated that ClO₂ above 500 ppm and 50% ethanol were effective in the carrier test method. In contrast, more than 200 ppm NaOCl and 50 ppm ClO₂ for all exposure times and 70% ethanol with contact for more than 5 min were effective in suspension tests. Treatment with PAA (80-2500 ppm) were not effective in carrier or suspension tests. Therefore, we recommend the use of more than 500 ppm ClO₂ or 50% ethanol with exposure for 10 min to disinfect surfaces that may be contaminated with HAV. Thus, these results could be effective in establishing official antiviral efficacy testing methods and basic data.

A Broad-Spectrum Antimicrobial and Antiviral Membrane Inactivates SARS-CoV-2 in Minutes

SARS-CoV-2, the virus that caused the COVID-19 pandemic, can remain viable and infectious on surfaces for days, posing a potential risk for fomite transmission. Liquid-based disinfectants, such as chlorine-based ones, have played an indispensable role in decontaminating surfaces but they do not provide prolonged protection from recontamination. Here a safe, inexpensive, and scalable membrane with covalently immobilized chlorine, large surface area, and fast wetting that exhibits long-lasting, exceptional killing efficacy against a broad spectrum of bacteria and viruses is reported. The membrane achieves a more than 6 log reduction within several minutes against all five bacterial strains tested, including gram-positive, gram-negative, and drug-resistant ones as well as a clinical bacterial cocktail. The membrane also efficiently deactivated nonenveloped and enveloped viruses in minutes. In particular, a 5.17 log reduction is achieved against SARS-CoV-2 after only 10 min of contact with the membrane. This membrane may be used on high-touch surfaces in healthcare and other public facilities or in air filters and personal protective equipment to provide continuous protection and minimize transmission risks.

Comparison of the disinfecting effect of sodium hypochlorite aqueous solution and surfactant on hospital kitchen hygiene using adenosine triphosphate swab testing

The Japanese Ministry of Health requires large-scale cooking facilities to use sodium hypochlorite aqueous solution (HYP) on food preparation tools, equipment, and facilities to prevent secondary contamination. This study aimed to compare the disinfecting effect of HYP and surfactant using adenosine triphosphate (ATP) swab testing on large-scale equipment and facilities that could not be disassembled and disinfected in hospital kitchen. From May 2018 to July 2018, ATP swab tests were performed on the following six locations in the Shizuoka Cancer Centre Dietary Department Kitchen: cooking counter, mobile cooking counter, refrigerator handle, conveyor belt, tap handle, and sink. Six relative light unit (RLU) measurements were taken from each location. The log₁₀ values of the RLU measurements were evaluated by dividing the samples into two groups: the control group (surfactant followed by HYP swabbing) and the HYP group (HYP swabbing only). The results showed that the RLUs (log₁₀ values) in both the groups improved after disinfection (p<0.05), except for the RLUs (log₁₀ values) of the mobile cooking counter, tap handle, and sink in the control group after the HYP swab. The changes in the RLU (log₁₀ value) did not differ between the two groups for all locations of the kitchen. Hence, HYP swabbing of large-scale equipment and facilities provides the same level of disinfection as surfactants and can be as beneficial.

A chronicle of SARS-CoV-2: Seasonality, environmental fate, transport, inactivation, and antiviral drug resistance

In this review, we present the environmental perspectives of the viruses and antiviral drugs related to SARS-CoV-2. The present review paper discusses occurrence, fate, transport, susceptibility, and inactivation mechanisms of viruses in the environment as well as environmental occurrence and fate of antiviral drugs, and prospects (prevalence and occurrence) of antiviral drug resistance (both antiviral drug resistant viruses and antiviral resistance in the human). During winter, the number of viral disease cases and environmental occurrence of antiviral drug surge due to various biotic and abiotic factors such as transmission pathways, human behaviour, susceptibility, and immunity as well as cold climatic conditions. Adsorption and persistence critically determine the fate and transport of viruses in the environment. Inactivation and disinfection of virus include UV, alcohol, and other chemical-base methods but the susceptibility of virus against these methods varies. Wastewater treatment plants (WWTPs) are major reserviors of antiviral drugs and their metabolites and transformation products. Ecotoxicity of antiviral drug residues against aquatic organisms have been reported, however more threatening is the development of antiviral resistance, both in humans and in wild animal reservoirs. In particular, emergence of antiviral drug-resistant viruses via exposure of wild animals to high loads of antiviral residues during the current pandemic needs further evaluation.

Meltblown fabric vs nanofiber membrane, which is better for fabricating personal protective equipments

The coronavirus disease 2019 (COVID-19) pandemic has led to a great demand on the personal protection products such as reusable masks. As a key raw material for masks, meltblown fabrics play an important role in rejection of aerosols. However, the electrostatic dominated aerosol rejection mechanism of meltblown fabrics prevents the mask from maintaining the desired protective effect after the static charge degradation. Herein, novel reusable masks with high aerosols rejection efficiency were fabricated by the introduction of spider-web bionic nanofiber membrane (nano cobweb-biomimetic membrane). The reuse stability of meltblown and nanofiber membrane mask was separately evaluated by infiltrating water, 75% alcohol solution, and exposing under ultraviolet (UV) light. After the water immersion test, the filtration efficiency of meltblown mask was decreased to about 79%, while the nanofiber membrane was maintained at 99%. The same phenomenon could be observed after the 75% alcohol treatment, a high filtration efficiency of 99% was maintained in nanofiber membrane, but obvious negative effect was observed in meltblown mask, which decreased to about 50%. In addition, after long-term expose under UV light, no filtration efficiency decrease was observed in nanofiber membrane, which provide a suitable way to disinfect the potential carried virus. This work successfully achieved the daily disinfection and reuse of masks, which effectively alleviate the shortage of masks during this special period.

Bactericidal and virucidal activity of ethanol and povidone-iodine

Ethanol and povidone‐iodine (PVP‐I) are important microbicides that inactivate bacteria and viruses. The present study provides a review of literature data on the concentration‐dependent bactericidal and virucidal activity of ethanol and PVP‐I in vitro. A systematic search was performed using the meta‐database for biomedicine PubMed. Eventually, 74 studies with original data on the reduction of bacterial and viral infectivity using in vitro tests were analyzed. A safe bactericidal effect of ethanol can be expected at concentrations between 60% and 85%, and the exposure times vary between ≤0.5 and ≥5 min. Within an exposure of up to 5 min, 80%–90% ethanol also exerts virucidal/low‐level activity, which includes its action against enveloped viruses plus adeno‐, noro‐, and rotaviruses. For PVP‐I, the best bactericidal and virucidal/high‐level effect is present at a concentration range of approx. 0.08%–0.9% depending on the free iodine concentration. The maximum exposure times are 5 min for bacteria and 60 min for viruses. The available data may help optimize the significant inactivation of bacteria and viruses in various areas. However, as the conditions in application practice can vary, concrete recommendations for the application can only be derived to a limited extent.

Situations Leading to Reduced Effectiveness of Current Hand Hygiene against Infectious Mucus from Influenza Virus-Infected Patients

Antiseptic hand rubbing (AHR) and antiseptic hand washing (AHW) are important to prevent the spread of influenza A virus (IAV). This study elucidated the situations/mechanisms underlying the reduced efficacy of AHR against infectious mucus derived from IAV-infected individuals and indicated the weaknesses of the current hand hygiene regimens. Due to the low rate of diffusion/convection because of the physical properties of mucus as a hydrogel, the efficacy of AHR using ethanol-based disinfectant against mucus is greatly reduced until infectious mucus adhering to the hands/fingers has completely dried. If there is insufficient time before treating the next patient (i.e., if the infectious mucus is not completely dry), medical staff should be aware that effectiveness of AHR is reduced. Since AHW is effective against both dry and nondry infectious mucus, AHW should be adopted to compensate for these weaknesses of AHR.

Both antiseptic hand rubbing (AHR) using ethanol-based disinfectants (EBDs) and antiseptic hand washing (AHW) are important means of infection control to prevent seasonal influenza A virus (IAV) outbreaks. However, previous reports suggest a reduced efficacy of ethanol disinfection against pathogens in mucus. We aimed to elucidate the situations and mechanisms underlying the reduced efficacy of EBDs against IAV in infectious mucus. We evaluated IAV inactivation and ethanol concentration change using IAV-infected patients’ mucus (sputum). Additionally, AHR and AHW effectiveness against infectious mucus adhering to the hands and fingers was evaluated in 10 volunteers. Our clinical study showed that EBD effectiveness against IAV in mucus was extremely reduced compared to IAV in saline. IAV in mucus remained active despite 120 s of AHR; however, IAV in saline was completely inactivated within 30 s. Due to the low rate of diffusion/convection because of the physical properties of mucus as a hydrogel, the time required for the ethanol concentration to reach an IAV inactivation level and thus for EBDs to completely inactivate IAV was approximately eight times longer in mucus than in saline. On the other hand, AHR inactivated IAV in mucus within 30 s when the mucus dried completely because the hydrogel characteristics were lost. Additionally, AHW rapidly inactivated IAV. Until infectious mucus has completely dried, infectious IAV can remain on the hands and fingers, even after appropriate AHR using EBD, thereby increasing the risk of IAV transmission. We clarified the ineffectiveness of EBD use against IAV in infectious mucus.

IMPORTANCE Antiseptic hand rubbing (AHR) and antiseptic hand washing (AHW) are important to prevent the spread of influenza A virus (IAV). This study elucidated the situations/mechanisms underlying the reduced efficacy of AHR against infectious mucus derived from IAV-infected individuals and indicated the weaknesses of the current hand hygiene regimens. Due to the low rate of diffusion/convection because of the physical properties of mucus as a hydrogel, the efficacy of AHR using ethanol-based disinfectant against mucus is greatly reduced until infectious mucus adhering to the hands/fingers has completely dried. If there is insufficient time before treating the next patient (i.e., if the infectious mucus is not completely dry), medical staff should be aware that effectiveness of AHR is reduced. Since AHW is effective against both dry and nondry infectious mucus, AHW should be adopted to compensate for these weaknesses of AHR.

Safely Managed Hygiene: A Risk-Based Assessment of Handwashing Water Quality

Sustainable Development Goal (SDG) Indicator 6.2.1 requires household handwashing facilities to have soap and water, but there are no guidelines for handwashing water quality. In contrast, drinking water quality guidelines are defined: water must be "free from contamination" to be defined as "safely managed" (SDG Indicator 6.1.1). We modeled the hypothesized mechanism of infection due to contaminated handwashing water to inform risk-based guidelines for microbial quality of handwashing water. We defined two scenarios that should not occur: (1) if handwashing caused fecal contamination, indicated using Escherichia coli, on a person's hands to increase rather than decrease and (2) if hand-to-mouth contacts following handwashing caused an infection risk greater than an acceptable threshold. We found water containing <1000 E. coli colony-forming units (CFU) per 100 mL removes E. coli from hands with>99.9% probability. However, for the annual probability of infection to be <1:1000, handwashing water must contain <2 × 10^-6 focus-forming units of rotavirus, <1 × 10^-4 CFU of Vibrio cholerae, and <9 × 10^-6 Cryptosporidium oocysts per 100 mL. Our model suggests that handwashing with nonpotable water will generally reduce fecal contamination on hands but may be unable to lower the annual probability of infection risks from hand-to-mouth contacts below 1:1000.

Quantitative Risk Assessment of Norovirus Transmission in Food Establishments: Evaluating the Impact of Intervention Strategies and Food Employee Behavior on the Risk Associated with Norovirus in Foods

We developed a quantitative risk assessment model using a discrete event framework to quantify and study the risk associated with norovirus transmission to consumers through food contaminated by infected food employees in a retail food setting. This study focused on the impact of ill food workers experiencing symptoms of diarrhea and vomiting and potential control measures for the transmission of norovirus to foods. The model examined the behavior of food employees regarding exclusion from work while ill and after symptom resolution and preventive measures limiting food contamination during preparation. The mean numbers of infected customers estimated for 21 scenarios were compared to the estimate for a baseline scenario representing current practices. Results show that prevention strategies examined could not prevent norovirus transmission to food when a symptomatic employee was present in the food establishment. Compliance with exclusion from work of symptomatic food employees is thus critical, with an estimated range of 75-226% of the baseline mean for full to no compliance, respectively. Results also suggest that efficient handwashing, handwashing frequency associated with gloving compliance, and elimination of contact between hands, faucets, and door handles in restrooms reduced the mean number of infected customers to 58%, 62%, and 75% of the baseline, respectively. This study provides quantitative data to evaluate the relative efficacy of policy and practices at retail to reduce norovirus illnesses and provides new insights into the interactions and interplay of prevention strategies and compliance in reducing transmission of foodborne norovirus.

Viscosity is an important factor of resistance to alcohol-based disinfectants by pathogens present in mucus

Alcohol-based disinfectants play an important role in the prevention of healthcare-acquired infection (HAI). We investigated whether pathogens present in mucus acquire resistance to alcohol-based disinfectants, and elucidated the underlying mechanism. Both the resistance of influenza A virus and Escherichia coli to alcohol-based disinfectants or ultraviolet irradiation and the diffusion rate of ethanol were determined in artificial mucus or sputum samples obtained from 27 individuals with acute upper respiratory infection. Pathogens in mucus (artificial mucus or sputum samples) were not completely inactivated by alcohol-based disinfectants (survival rate >10%), suggesting that the alcohol-based disinfectants were ineffective. Pathogen survival and mucus viscosity were strongly correlated (correlation coefficient >0.7, P < 0.001). Additionally, the ethanol diffusion rate decreased with increasing mucus viscosity, which contributed to ethanol resistance. Pronase treatment of sputum samples significantly decreased sputum viscosity and increased the disinfectant effect (P < 0.001 for all). In contrast, complete inactivation was achieved by ultraviolet irradiation independently of mucus viscosity. Thus, mucus viscosity contributes to resistance of pathogens to alcohol-based disinfectants by decreasing the alcohol diffusion rate. These findings can provide a basis for developing new strategies, including improved disinfectants, for overcoming HAI.

Efficacy of ethanol against viruses in hand disinfection

Ethanol is used worldwide in healthcare facilities for hand rubbing. It has been reported to have a stronger and broader virucidal activity compared with propanols. The aim of this review was to describe the spectrum of virucidal activity of ethanol in solution or as commercially available products. A systematic search was conducted. Studies were selected when they contained original data on reduction of viral infectivity from suspension tests (49 studies) and contaminated hands (17 studies). Ethanol at 80% was highly effective against all 21 tested, enveloped viruses within 30 s. Murine norovirus and adenovirus type 5 are usually inactivated by ethanol between 70% and 90% in 30 s whereas poliovirus type 1 was often found to be too resistant except for ethanol at 95% (all test viruses of EN 14476). Ethanol at 80% is unlikely to be sufficiently effective against poliovirus, calicivirus (FCV), polyomavirus, hepatitis A virus (HAV) and foot-and-mouth disease virus (FMDV). The spectrum of virucidal activity of ethanol at 95%, however, covers the majority of clinically relevant viruses. Additional acids can substantially improve the virucidal activity of ethanol at lower concentrations against, e.g. poliovirus, FCV, polyomavirus and FMDV although selected viruses such as HAV may still be too resistant. The selection of a suitable virucidal hand rub should be based on the viruses most prevalent in a unit and on the user acceptability of the product under frequent-use conditions.

Effects of disinfectants against norovirus virus-like particles predict norovirus inactivation

Human noroviruses (NoVs) are a major cause of epidemic and sporadic acute gastroenteritis worldwide. Public and personal hygiene is one of the most important countermeasures for preventing spread of NoV infection. However, no a practicable cell culture system for NoV had been developed, initial tests of the virucidal effectiveness of anti-NoV disinfectants and sanitizers have been performed using surrogate viruses. In this study, NoV virus-like particles (VLPs) were used as a new surrogate for NoVs and a method for evaluating NoV inactivation using them developed. This method is based on morphological changes in VLPs after treatment with sodium hypochlorite. VLP specimens were found to become deformed and degraded in a concentration-dependent manner. Based on these results, the effects of sodium hypochlorite on VLPs were classified into four phases according to morphological changes and number of particles. Using the criteria thus established, the efficacy of ethanol, carbonates and alkali solutions against VLPs was evaluated. Deformation and aggregation of VLPs were observed after treatment with these disinfectants under specific conditions. To determine the degradation mechanism(s), VLPs were examined by SDS-PAGE and immunoblotting after treatment with sodium hypochlorite and ethanol. The band corresponding to the major capsid protein, VP1, was not detected after treatment with sodium hypochlorite at concentrations greater than 500 ppm, but remained after treatment with ethanol. These results suggest that VLPs have excellent potential as a surrogate marker for NoVs and can be used in initial virucidal effectiveness tests to determine the mechanism(s) of chemical agents on NoVs.

Intra-family differences in efficacy of inactivation of small, non-enveloped viruses

The use of specific model viruses for validating viral purification process steps and for assessing the efficacies of viral disinfectants is based, in part, on the assumption that viral susceptibilities to such treatments will be similar for different members, including different genera, within a given viral family. This assumption is useful in cases where cell-based infectivity assays or laboratory strains for the specific viruses of interest might not exist. There are some documented cases, however, where exceptions to this assumption exist. In this paper, we discuss some of the more striking cases of intra-family differences in susceptibilities to inactivation steps used for downstream viral purification steps in biologics manufacture (e.g. heat inactivation, low pH, and guanidinium hydrochloride inactivation) and to specific viral disinfectants (e.g. alcohols, hydrogen peroxide, and quaternary ammonium-containing disinfectants) that might be employed for facility/equipment disinfection. The results suggest that care should be taken when extrapolating viral inactivation susceptibilities from specific model viruses to different genera or even to different members of the same genus. This should be taken into consideration by regulatory agencies and biologics manufacturers designing viral clearance and facility disinfection validation studies, and developers and evaluators of viral disinfectants.

Lessons Learned From a Norovirus Outbreak in a Locked Pediatric Inpatient Psychiatric Unit

We report an outbreak of norovirus in a locked pediatric inpatient psychiatric unit with attack rates of 75% among 4 patients and 26% among 38 staff. Factors contributing to the outbreak included environmental contamination, close staff-patient contact including sharing meals, and inability to confine the index patient with the use of contact precautions.

Efficacy of Instant Hand Sanitizers against Foodborne Pathogens Compared with Hand Washing with Soap and Water in Food Preparation Settings: A Systematic Review

Hands can be a vector for transmitting pathogenic microorganisms to foodstuffs and drinks, and to the mouths of susceptible hosts. Hand washing is the primary barrier to prevent transmission of enteric pathogens via cross-contamination from infected persons. Conventional hand washing involves the use of water, soap, and friction to remove dirt and microorganisms. The availability of hand sanitizing products for use when water and soap are unavailable has increased in recent years. The aim of this systematic review was to collate scientific information on the efficacy of hand sanitizers compared with washing hands with soap and water for the removal of foodborne pathogens from the hands of food handlers. An extensive literature search was carried out using three electronic databases: Web of Science, Scopus, and PubMed. Twenty-eight scientific publications were ultimately included in the review. Analysis of this literature revealed various limitations in the scientific information owing to the absence of a standardized protocol for evaluating the efficacy of hand products and variation in experimental conditions. However, despite conflicting results, scientific evidence seems to support the historical skepticism about the use of waterless hand sanitizers in food preparation settings. Water and soap appear to be more effective than waterless products for removal of soil and microorganisms from hands. Alcohol-based products achieve rapid and effective inactivation of various bacteria, but their efficacy is generally lower against nonenveloped viruses. The presence of food debris significantly affects the microbial inactivation rate of hand sanitizers.

Strategies to Prevent Healthcare-Associated Infections through Hand Hygiene

Previously published guidelines provide comprehensive recommendations for hand hygiene in healthcare facilities. The intent of this document is to highlight practical recommendations in a concise format, update recommendations with the most current scientific evidence, and elucidate topics that warrant clarification or more robust research. Additionally, this document is designed to assist healthcare facilities in implementing hand hygiene adherence improvement programs, including efforts to optimize hand hygiene product use, monitor and report back hand hygiene adherence data, and promote behavior change. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA) and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the American Hospital Association (AHA), the Association for Professionals in Infection Control and Epidemiology (APIC), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. The list of endorsing and supporting organizations is presented in the introduction to the 2014 updates.

Strategies to prevent healthcare-associated infections through hand hygiene

Previously published guidelines provide comprehensive recommendations for hand hygiene in healthcare facilities. The intent of this document is to highlight practical recommendations in a concise format, update recommendations with the most current scientific evidence, and elucidate topics that warrant clarification or more robust research. Additionally, this document is designed to assist healthcare facilities in implementing hand hygiene adherence improvement programs, including efforts to optimize hand hygiene product use, monitor and report back hand hygiene adherence data, and promote behavior change. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA) and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the American Hospital Association (AHA), the Association for Professionals in Infection Control and Epidemiology (APIC), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. The list of endorsing and supporting organizations is presented in the introduction to the 2014 updates.

Reducing viral contamination from finger pads: handwashing is more effective than alcohol-based hand disinfectants

BACKGROUND

Hand hygiene is important for interrupting transmission of viruses through hands. Effectiveness of alcohol-based hand disinfectant has been shown for bacteria but their effectiveness in reducing transmission of viruses is ambiguous.

AIM

To test efficacy of alcohol hand disinfectant against human enteric and respiratory viruses and to compare efficacy of an alcohol-based hand disinfectant and handwashing with soap and water against norovirus.

METHODS

Efficacies of a propanol and an ethanol-based hand disinfectant against human enteric and respiratory viruses were tested in carrier tests. Efficacy of an alcohol-based hand disinfectant and handwashing with soap and water against noroviruses GI.4, GII.4, and MNV1 were tested using finger pad tests.

FINDINGS

The alcohol-based hand disinfectant reduced the infectivity of rotavirus and influenza A virus completely within 30s whereas poliovirus Sabin 1, adenovirus type 5, parechovirus 1, and MNV1 infectivity were reduced <3 log10 within 3 min. MNV1 infectivity reduction by washing hands with soap and water for 30s (>3.0 ± 0.4 log10) was significantly higher than treating hands with alcohol (2.8 ± 1.5 log10). Washing with soap and water for 30s removed genomic copies of MNV1 (>5 log10), noroviruses GI.4 (>6 log10), and GII.4 (4 log10) completely from all finger pads. Treating hands with propanol-based hand disinfectant showed little or no reduction to complete reduction with mean genomic copy reduction of noroviruses GI.4, GII.4, and MNV1 being >2.6, >3.3, and >1.2 log10 polymerase chain reaction units respectively.

CONCLUSIONS

Washing hands with soap and water is better than using alcohol-based hand disinfectants in removing noroviruses from hands.

Prevention of Nosocomial Transmission of Norovirus by Strategic Infection Control Measures

Background.

Nosocomial outbreaks of norovirus infection pose a great challenge to the infection control team.

Methods.

Between November 1, 2009, and February 28, 2010, strategic infection control measures were implemented in a hospital network. In addition to timely staff education and promotion of directly observed hand hygiene, reverse-transcription polymerase chain reaction for norovirus was performed as an added test by the microbiology laboratory for all fecal specimens irrespective of the request for testing. Laboratory-confirmed cases were followed up by the infection control team for timely intervention. The incidence of hospital-acquired norovirus infection per 1,000 potentially infectious patient-days was compared with the corresponding period in the preceding 12 months, and the incidence in the other 6 hospital networks in Hong Kong was chosen as the concurrent control. Phylogenetic analysis of norovirus isolates was performed.

Results.

Of the 988 patients who were tested, 242 (25%) were positive for norovirus; 114 (47%) of those 242 patients had norovirus detected by our added test. Compared with the corresponding period in the preceding 12 months, the incidence of hospital-acquired norovirus infection decreased from 131 to 16 cases per 1,000 potentially infectious patient-days (P < .001 ), although the number of hospital-acquired infections was low in both the study period (n = 8) and the historical control periods (n = 11). The incidence of hospital-acquired norovirus infection in our hospital network (0.03 cases per 1,000 patient-days) was significantly lower than that of the concurrent control (0.06 cases per 1,000 patient-days) (P = .015). Forty-three (93%) of 46 norovirus isolates sequenced belonged to the genogroup II.4 variant.

Conclusions.

Strategic infection control measures with an added test maybe useful in controlling nosocomial transmission of norovirus.

Norovirus

Norovirus, an RNA virus of the family Caliciviridae, is a human enteric pathogen that causes substantial morbidity across both health care and community settings. Several factors enhance the transmissibility of norovirus, including the small inoculum required to produce infection (<100 viral particles), prolonged viral shedding, and its ability to survive in the environment. In this review, we describe the basic virology and immunology of noroviruses, the clinical disease resulting from infection and its diagnosis and management, as well as host and pathogen factors that complicate vaccine development. Additionally, we discuss overall epidemiology, infection control strategies, and global reporting efforts aimed at controlling this worldwide cause of acute gastroenteritis. Prompt implementation of infection control measures remains the mainstay of norovirus outbreak management.

Comprehensive comparison of cultivable norovirus surrogates in response to different inactivation and disinfection treatments

Human norovirus is the leading cause of epidemic and sporadic acute gastroenteritis. Since no cell culture method for human norovirus exists, cultivable surrogate viruses (CSV), including feline calicivirus (FCV), murine norovirus (MNV), porcine enteric calicivirus (PEC), and Tulane virus (TuV), have been used to study responses to inactivation and disinfection methods. We compared the levels of reduction in infectivities of CSV and Aichi virus (AiV) after exposure to extreme pHs, 56°C heating, alcohols, chlorine on surfaces, and high hydrostatic pressure (HHP), using the same matrix and identical test parameters for all viruses, as well as the reduction of human norovirus RNA levels under these conditions. At pH 2, FCV was inactivated by 6 log10 units, whereas MNV, TuV, and AiV were resistant. All CSV were completely inactivated at 56°C within 20 min. MNV was inactivated 5 log10 units by alcohols, in contrast to 2 and 3 log10 units for FCV and PEC, respectively. TuV and AiV were relatively insensitive to alcohols. FCV was reduced 5 log10 units by 1,000 ppm chlorine, in contrast to 1 log10 unit for the other CSV. All CSV except FCV, when dried on stainless steel surfaces, were insensitive to 200 ppm chlorine. HHP completely inactivated FCV, MNV, and PEC at ≥300 MPa, and TuV at 600 MPa, while AiV was completely resistant to HHP up to 800 MPa. By reverse transcription-quantitative PCR (RT-qPCR), genogroup I (GI) noroviruses were more sensitive than GII noroviruses to alcohols, chlorine, and HHP. Although inactivation profiles were variable for each treatment, TuV and MNV were the most resistant CSV overall and therefore are the best candidates for studying the public health outcomes of norovirus infections.

Virucidal activity of Formulation I of the World Health Organization's alcohol-based handrubs: impact of changes in key ingredient levels and test parameters

BACKGROUND

A recently modified World Health Organization (WHO) Formulation I was examined as 80% and 97% solutions against poliovirus type 1, adenovirus type 5 and murine norovirus according to the new European Norm prEN 14476:2011. In a previous study the unmodified WHO Formulation I had failed to demonstrate a sufficient activity against poliovirus type 1 according to the European Norm EN 14476-2007 whereas a sufficient activity was seen with adeno- and norovirus.

FINDINGS

The modified WHO Formulation I demonstrated a virucidal activity against all 3 test viruses of the European Norm prEN 14476:2011 under clean conditions. This was achieved as 80% solution against adeno- and norovirus within 30 seconds and as 97% solution against poliovirus within 60 seconds. Testing the unmodified WHO Formulation I against poliovirus type 1 in the 97% assay of the European Norm prEN 14476:2011 an identical activity could be demonstrated. When comparing the 80% and the 97% assay of the European Norm prEN 14476:2011 the modified WHO Formulation I as 80% solution was active against adenovirus type 5 within 30 seconds whereas the 97% solution failed within 2 minutes exposure time.

CONCLUSIONS

The technical possibility in the new European Norm prEN 14476:2011 allows testing a ready-to-use disinfectant as 97% solution and is responsible for the new virucidal claim of the modified WHO Formulation I. In contrast to the improvements with poliovirus type 1 the activity against adenovirus type 5 decreased when increasing the test concentration from 80% to 97%.

Efficacy of commonly used disinfectants for inactivation of human noroviruses and their surrogates

Human noroviruses (HuNoVs) are the most common cause of acute viral gastroenteritis worldwide and are a leading cause of foodborne disease. Their environmental persistence and purported resistance to disinfection undoubtedly contribute to their success as foodborne disease agents. The purpose of this study was to compare the efficacy of three commonly used disinfectant active ingredients against representative HuNoV strains and cultivable surrogates. Ethanol (50, 70, and 90%), sodium hypochlorite (5, 75, 250, 500, and 1,000 ppm), and a quaternary ammonium compound blend (at 0.1×, 1.0×, and 10× concentrations) were evaluated against two norovirus (NoV) genogroup II strains (GII.2 and GII.4) and two surrogates (feline calicivirus [FCV] and murine norovirus [MNV-1]). Virucidal suspension assays (30-s exposure) were conducted in accordance with ASTM International standard E-1052. Virus inactivation was quantified using reverse transcription quantitative PCR targeting the ORFI-ORFII junction (HuNoV), the RNA polymerase region (MNV-1), or the ORFI region (FCV); infectivity assays were also performed for MNV-1 and FCV. The two HuNoV strains and FCV were relatively resistant to ethanol (<0.5 log inactivation) irrespective of concentration, but MNV-1 was much more susceptible (log inactivation, ∼2.0 log at higher ethanol concentrations). Both HuNoV strains were more resistant to hypochlorite than were either of the animal surrogates, with the human strains requiring ≥500 ppm of hypochlorite to achieve statistically significant reduction (≥3.0 log) in virus concentration. All four viruses were resistant to inactivation (<0.5-log reduction) using the quaternary ammonium compound formulation at all concentrations tested. This study is novel in that it clearly demonstrates the relative ineffectiveness of common active disinfectant ingredients against HuNoV and highlights the fact that the cultivable surrogates do not always mimic HuNoV strains.

A risk assessment approach to use of antimicrobials in the home to prevent spread of infection

Home and everyday life hygiene is a key part of the public health strategy to reduce infectious disease, but an effective code of practice is required. This short review summarizes the basic scientific principles of a risk-based approach to home hygiene where hygiene procedures are applied at critical points at appropriate times. It suggests that, although detergent-based cleaning can be used to break the chain of infection, in some cases an antimicrobial agent is required.

Inactivation of the Tulane virus, a novel surrogate for the human norovirus

Human noroviruses (HuNoVs) are the major cause of nonbacterial gastroenteritis epidemics. The culturable feline calicivirus and murine norovirus have been used extensively as surrogates to study HuNoV biology, as HuNoV does not grow in vitro. Additional efforts to identify new surrogates are needed, because neither of these common surrogates are truly intestinal pathogens. The newly described Tulane virus (TV) is a typical calicivirus, it is isolated from macaque stools, is cultivable in vitro, and recognizes human histo-blood group antigens. Therefore, TV is a promising surrogate for HuNoVs. In this study, we evaluated the resistance or stability of TV under various physical and environmental conditions by measuring a 50% reduction of tissue culture infective dose (TCID50) by using a TV cell culture system. Due to the nature of this virus, it is hard to produce a high-titer stock through tissue culture. In our study, the maximal reduction in virus titers was 5D (D = 1 log) in heat-denaturation and EtOH experiments, and 4D in UV, chlorine, and pH-stability experiments. Therefore in this study, we defined the inactivation of TV as reaching a TCID50/ml of 0 (a 4- to 5-D reduction in TCID50, depending on the detection limit). TV was inactivated after incubation at 63 °C for 5 min, incubation at 56 °C for 30 min (5D), exposure to 60 mJ/cm2 of UVC radiation (4D), or incubation at 300 ppm of free chlorine for 10 min (4D). TV was shown to be stable from pH 3.0 to 8.0, though an obvious reduction in virus titer was observed at pH 2.5 and 9.0, and was inactivated at pH 10.0 (4D). TV was resistant to a low concentration of EtOH (40% or lower) but was fully inactivated (5D) by 50 to 70% EtOH after a short exposure (20 s). In contrast, quantitative real-time PCR was unable to detect, or poorly detected, virus titer reductions between treated and untreated samples described in this study.

Inactivation of caliciviruses

The Caliciviridae family of viruses contains clinically important human and animal pathogens, as well as vesivirus 2117, a known contaminant of biopharmaceutical manufacturing processes employing Chinese hamster cells. An extensive literature exists for inactivation of various animal caliciviruses, especially feline calicivirus and murine norovirus. The caliciviruses are susceptible to wet heat inactivation at temperatures in excess of 60 °C with contact times of 30 min or greater, to UV-C inactivation at fluence ≥30 mJ/cm2, to high pressure processing >200 MPa for >5 min at 4 °C, and to certain photodynamic inactivation approaches. The enteric caliciviruses (e.g.; noroviruses) display resistance to inactivation by low pH, while the non-enteric species (e.g.; feline calicivirus) are much more susceptible. The caliciviruses are inactivated by a variety of chemicals, including alcohols, oxidizing agents, aldehydes, and β-propiolactone. As with inactivation of viruses in general, inactivation of caliciviruses by the various approaches may be matrix-, temperature-, and/or contact time-dependent. The susceptibilities of the caliciviruses to the various physical and chemical inactivation approaches are generally similar to those displayed by other small, non-enveloped viruses, with the exception that the parvoviruses and circoviruses may require higher temperatures for inactivation, while these families appear to be more susceptible to UV-C inactivation than are the caliciviruses.

Efficacy of alcohols and alcohol-based hand disinfectants against human enterovirus 71

BACKGROUND

Human enterovirus 71 (HEV71) infections are a significant public health threat in the Asia-Pacific region and occasionally cause severe neurological complications and even death in children. Although good hand hygiene is important for controlling infection, relevant data regarding the efficacy of widely used hand disinfectants against HEV71 are still lacking.

AIM

To investigate the virucidal activity of alcohols and alcohol-based hand disinfectants against HEV71.

METHODS

A common alcohol-based hand disinfectant (0.5% chlorhexidine gluconate + 70% isopropanol) as well as different concentrations of isopropanol and ethanol were tested for virucidal activity against HEV71 using the suspension and the fingerpad tests.

FINDINGS

In suspension tests, 85% and 95% ethanol achieved a mean log10 reduction factor in HEV71 titre of >3 and nearly 6, respectively, within 10 min. By contrast, 70% and 75% ethanol and any concentration of isopropanol (70-95%) produced a factor of <1 in this test after the same exposure time. In fingerpad tests, only 95% ethanol showed a mean log10 reduction factor of >4, while both 75% ethanol and a chlorhexidine gluconate-containing formula were ineffective against HEV71 with a mean log10 reduction factor of <1 after a 30 s exposure time.

CONCLUSIONS

Widely used alcohol-based hand disinfectants based on 70% ethanol or isopropanol have poor effectiveness against HEV71. Ninety-five percent ethanol is the most effective concentration, but still cannot fully inactivate HEV71 and may be impractical for use in many instances. Hand hygiene with alcohol-based hand disinfectants alone is not recommended for preventing HEV71 transmission.

Virucidal activity of alcohol-based hand rub disinfectants

We investigated the virucidal activity of commercially available alcohol-based hand rub products against coxsackievirus A7, B5, feline calicivirus F9, and human adenovirus type 3, type 7, type 8 using susceptible cell lines, Vero cells, CRFK cells, and A549 cells. Fifteen tested hand rub products were ethanol (EtOH) for disinfection (Japanese Pharmacopoeia Grade), two EtOH-based products, one povidone iode-containing product, one alkyldiaminoethylglycine hydrochloride-containing product, six benzalkonium chloride (BAK)-containing products, and four chlorohexidine gluconate (CHG)-containing products. Some active ingredients (BAK, benzetonium chloride, and CHG) were diluted with EtOH to make 0.5% and 0.2% solutions. Virus inactivation rates were calculated after contact with each hand rub product for 10 or 60 seconds. Of the hand rub products tested, only the povidone iode-based product showed antiviral activity superior to that of EtOH against all the strains. EtOH solutions of active ingredients (0.2% and 0.5%) also showed decreased antiviral activity. In conclusion, antiviral activity of all the commercially available alcohol-based hand rub products except that containing povidone idode was dependent on their active ingredients. The povidone idode-containing hand rub product kept its effectiveness even after the dilution with EtOH. Although alcohol-based hand rub products are convenient and suitable for the control of some microbes, they are not generally recommended for the control of viral infections.

Hand hygiene regimens for the reduction of risk in food service environments

Pathogenic strains of Escherichia coli and human norovirus are the main etiologic agents of foodborne illness resulting from inadequate hand hygiene practices by food service workers. This study was conducted to evaluate the antibacterial and antiviral efficacy of various hand hygiene product regimens under different soil conditions representative of those in food service settings and assess the impact of product formulation on this efficacy. On hands contaminated with chicken broth containing E. coli, representing a moderate soil load, a regimen combining an antimicrobial hand washing product with a 70% ethanol advanced formula (EtOH AF) gel achieved a 5.22-log reduction, whereas a nonantimicrobial hand washing product alone achieved a 3.10log reduction. When hands were heavily soiled from handling ground beef containing E. coli, a wash-sanitize regimen with a 0.5% chloroxylenol antimicrobial hand washing product and the 70% EtOH AF gel achieved a 4.60-log reduction, whereas a wash-sanitize regimen with a 62% EtOH foam achieved a 4.11-log reduction. Sanitizing with the 70% EtOH AF gel alone was more effective than hand washing with a nonantimicrobial product for reducing murine norovirus (MNV), a surrogate for human norovirus, with 2.60- and 1.79-log reductions, respectively. When combined with hand washing, the 70% EtOH AF gel produced a 3.19-log reduction against MNV. A regimen using the SaniTwice protocol with the 70% EtOH AF gel produced a 4.04-log reduction against MNV. These data suggest that although the process of hand washing helped to remove pathogens from the hands, use of a wash-sanitize regimen was even more effective for reducing organisms. Use of a high-efficacy sanitizer as part of a wash-sanitize regimen further increased the efficacy of the regimen. The use of a well-formulated alcohol-based hand rub as part of a wash-sanitize regimen should be considered as a means to reduce risk of infection transmission in food service facilities.

Critical review of norovirus surrogates in food safety research: rationale for considering volunteer studies

The inability to propagate human norovirus (NoV) or to clearly differentiate infectious from noninfectious virus particles has led to the use of surrogate viruses, like feline calicivirus (FCV) and murine norovirus-1 (MNV), which are propagatable in cell culture. The use of surrogates is predicated on the assumption that they generally mimic the viruses they represent; however, studies are proving this concept invalid. In direct comparisons between FCV and MNV, their susceptibility to temperatures, environmental and food processing conditions, and disinfectants are dramatically different. Differences have also been noted between the inactivation of NoV and its surrogates, thus questioning the validity of surrogates. Considerable research funding is provided globally each year to conduct surrogate studies on NoVs; however, there is little demonstrated benefit derived from these studies in regard to the development of virus inactivation techniques or food processing strategies. Human challenge studies are needed to determine which processing techniques are effective in reducing NoVs in foods. A major obstacle to clinical trials on NoVs is the perception that such trials are too costly and risky, but in reality, there is far more cost and risk in allowing millions of unsuspecting consumers to contract NoV illness each year, when practical interventions are only a few volunteer studies away. A number of clinical trials have been conducted, providing important insights into NoV inactivation. A shift in research priorities from surrogate research to volunteer studies is essential if we are to identify realistic, practical, and scientifically valid processing approaches to improve food safety.

Use of alcohol-based hand sanitizers as a risk factor for norovirus outbreaks in long-term care facilities in northern New England: December 2006 to March 2007

BACKGROUND

During December 2006 to March 2007, a substantial increase in norovirus illnesses was noted in northern New England. We sought to identify institutional risk factors for norovirus outbreaks in northern New England long-term care facilities (LTCFs).

METHODS

State health departments in Maine, New Hampshire, and Vermont distributed surveys to infection preventionists at all LTCFs in their respective states. We collected information regarding facility attributes, routine staff use of alcohol-based hand sanitizer (ABHS) versus soap and water, facility cleaning practices, and occurrence of any acute gastroenteritis outbreaks during December 2006 to March 2007. Norovirus confirmation was conducted in public health laboratories. Data were analyzed with univariate and logistic regression methods.

RESULTS

Of 160 facilities, 91 (60%) provided survey responses, with 61 facilities reporting 73 outbreaks; 29 were confirmed norovirus. Facilities reporting that staff were equally or more likely to use ABHS than soap and water for routine hand hygiene had higher odds of an outbreak than facilities with staff less likely to use ABHS (adjusted odds ratio, 6.06; 95% confidence interval: 1.44-33.99).

CONCLUSION

This study suggests that preferential use of ABHS over soap and water for routine hand hygiene might be associated with increased risk of norovirus outbreaks in LTCFs.

Comparison of the Activity of Alcohol-Based Handrubs Against Human Noroviruses Using the Fingerpad Method and Quantitative Real-Time PCR

Noroviruses (NoV) are the most common cause of acute nonbacterial gastroenteritis in the United States, and human hands play an important role in their transmission. Little is known about the efficacy of hand hygiene agents against these highly infectious pathogens. We investigated the activity of seven commercially available hand hygiene products against human noroviruses by in vivo fingerpad tests. The in vivo activity of alcohol-based handrubs ranged from 0.10 to 3.74 log reduction and was not solely dependent on alcohol concentration. A handrub (VF481) based on 70% ethanol and a blend of other skin care ingredients reduced Norwalk virus (NV) by 3.74 log in 15 s and provided significantly greater NV reduction than all the other products tested (P < 0.001). Furthermore, VF481 was the most effective product tested against the NoV genogroup II strains Snow Mountain virus (GII.2) and a GII.4 strain. These results demonstrate that alcohol by itself is not effective against NoV, but effective formulation of alcohol-based handrubs can achieve significant reduction of norovirus RNA on fingers.

In vivo comparison of two human norovirus surrogates for testing ethanol-based handrubs: the mouse chasing the cat!

Human noroviruses (HuNoV), a major cause of acute gastroenteritis worldwide, cannot be readily cultured in the lab. Therefore, a feline calicivirus (FCV) is often used as its surrogate to, among other things, test alcohol-based handrubs (ABHR). The more recent laboratory culture of a mouse norovirus (MNV) provides an alternative. While MNV is closer to HuNoV in several respects, to date, no comparative testing of FCV and MNV survival and inactivation on human hands has been performed. This study was designed to address the knowledge gap. The rates of loss in viability during drying on hands were -1.91 and -1.65% per minute for FCV and MNV, respectively. When the contaminated skin was exposed for 20 s to either a commercial ABHR with 62% (v/v) ethanol or to 75% (v/v) ethanol in water, FCV infectivity was reduced by <1 log₁₀ while that of MNV by nearly 2.8 log₁₀. Extending the contact time to 30 s reduced the FCV titer by almost 2 log₁₀ by both test substances and that of MNV by >3.5 log₁₀ by the commercial ABHR while 75% ethanol did not show any noticeable improvement in activity as compared to the 20 s contact. An 80% (v/v) aqueous solution of ethanol gave only a 1.75 log₁₀ reduction in MNV activity after 20 s. The results show significant differences in the ethanol susceptibility of FCV and MNV in contact times relevant to field use of ABHR and also that 62% ethanol was a more effective virucide than either 75% or 80% ethanol. These findings indicate the need for a review of the continuing use of FCV as a surrogate for HuNoV.

Comparative efficacy of seven hand sanitizers against murine norovirus, feline calicivirus, and GII.4 norovirus

Contaminated hands or inanimate surfaces can act as a source of infection during outbreaks of human norovirus infection. We evaluated the virucidal efficacy of seven hand sanitizers containing various active ingredients, such as ethanol, triclosan, and chlorhexidine, and compared their effectiveness against feline calicivirus (FCV), murine norovirus (MNV), and a GII.4 norovirus fecal extract. We also tested the efficacy of 50, 70, and 90% of ethanol and isopropanol. Reduction of viral infectivity was measured by plaque assay, and the number of genomic copies was determined with a TaqMan real-time reverse transcription PCR assay. Based on the results of a quantitative suspension test, only one ethanol-based product (72% ethanol, pH 2.9) and one triclosan-based product (0.1% triclosan, pH 3.0) reduced the infectivity of both MNV and FCV (by >2.6 and ≥3.4 log units, respectively). Four of the seven products were effective against either MNV or FCV, whereas chlorhexidine was ineffective against both viruses. For these hand sanitizers, no correlation was found between reduced infectivity and decline of viral RNA. Ethanol and isopropanol concentrations ≥70% reduced the infectivity of MNV by ≥2.6 log units, whereas 50 and 70% ethanol reduced the infectivity of FCV by ≥2.2 log units after exposure for 5 min. The susceptibility of FCV to low pH and the relative high susceptibility of MNV to alcohols suggest that both surrogate viruses should be considered for in vitro testing of hand sanitizers.