Virucidal efficacy of the newer quaternary ammonium compounds

Distribution of SARS-CoV-2 RNA signal in a home with COVID-19 positive occupants

Although many COVID-19 patients isolate and recover at home, the dispersal of SARS-CoV-2 onto surfaces and dust within the home environment remains poorly understood. To investigate the distribution and persistence of SARS-CoV-2 in a home with COVID-19 positive occupants, samples were collected from a household with two confirmed COVID-19 cases (one adult and one child). Home surface swab and dust samples were collected two months after symptom onset (and one month after symptom resolution) in the household. The strength of the SARS-CoV-2 molecular signal in fomites varied as a function of sample location, surface material and cleaning practices. Notably, the SARS-CoV-2 RNA signal was detected at several locations throughout the household although cleaning appears to have attenuated the signal on many surfaces. Of the 24 surfaces sampled, 46% were SARS-CoV-2 positive at the time of sampling. The SARS-CoV-2 concentrations in dust recovered from floor and HVAC filter samples ranged from 104 to 105 N2 gene copies/g dust. While detection of viral RNA does not imply infectivity, this study confirms that the SARS-CoV-2 RNA signal can be detected at several locations within a COVID-19 isolation home and can persist after symptoms have resolved. In addition, the concentration of SARS-CoV-2 (normalized per unit mass of dust) recovered in home HVAC filters may prove useful for estimating SARS-CoV-2 airborne levels in homes. In this work, using the quantitative filter forensics methodology, we estimated an average integrated airborne SARS-CoV-2 concentration of 69 ± 43 copies/m3. This approach can be used to help building scientists and engineers develop best practices in homes with COVID-19 positive occupants.

Sanitizing agents for virus inactivation and disinfection

Viral epidemics develop from the emergence of new variants of infectious viruses. The lack of effective antiviral treatments for the new viral infections coupled with rapid community spread of the infection often result in major human and financial loss. Viral transmissions can occur via close human-to-human contact or via contacting a contaminated surface. Thus, careful disinfection or sanitization is essential to curtail viral spread. A myriad of disinfectants/sanitizing agents/biocidal agents are available that can inactivate viruses, but their effectiveness is dependent upon many factors such as concentration of agent, reaction time, temperature, and organic load. In this work, we review common commercially available disinfectants agents available on the market and evaluate their effectiveness under various application conditions. In addition, this work also seeks to debunk common myths about viral inactivation and highlight new exciting advances in the development of potential sanitizing agents.

Shelter housing for cats: Practical aspects of design and construction, and adaptation of existing accommodation

Practical relevance: Not every cat shelter will have purpose-built accommodation but housing designed with the basic needs of cats in mind, whether purpose-built or adapted from existing housing, will improve the experience of cats passing through the facility. Challenges: Designing and building accommodation for cats in shelters should be a thoughtful process. There is a range of different housing types available. A variety of factors, such as expected length of stay, type of cat, cost and disease risk, will influence which design is most appropriate.

AIMS

This review, the second in a two-part series, provides an overview of some of the essential requirements for housing shelter cats, either singly or in groups. Specific practical aspects of housing, including design, space allowances, cage furnishings and suitable construction materials, are discussed, and suggestions made for upgrading existing housing where extensive rebuilding is not feasible or realistic. Evidence base: There is a relatively small body of empirical evidence to inform shelter design recommendations. The recommendations in this article are based on a careful review of the available evidence, some of which has come from allied fields such as the care of experimental animals. Where evidence is not yet available, recommendations have been based on field experience and collective expert opinion.

Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance

Microbial infections affect humans worldwide. Many quaternary ammonium compounds have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for preparation of antimicrobial biomaterials. Various polymerization techniques have been employed to prepare antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymerization techniques enable precise control over macromolecular structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technological developments have also been accompanied by potential toxicological and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-containing biomaterials that are based on randomized human clinical trials, the golden standard in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.

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.

Virucidal efficacy of disinfectant actives against feline calicivirus, a surrogate for norovirus, in a short contact time

BACKGROUND

Among other measures, handwashing and targeted disinfection are important in preventing and controlling norovirus outbreaks. Presently, there are a limited number of disinfectants effective against norovirus. There is a need to develop alternatives to bleach that are effective against norovirus, and, in particular, fast-acting disinfectants are desired. The aim of this study was to determine the disinfectant actives and formulation factors necessary to achieve efficacy against norovirus in a short contact time.

METHODS

Feline calicivirus (FCV) was used as a surrogate for norovirus. In a carrier test method, common disinfectant actives including alcohol, acid, quaternary compound, and phenol both alone and as formulated disinfectants were contacted with dried FCV virus for 1 minute. The virus treatment was neutralized and assayed in Crandell-Reese kidney cells for cytopathic effect. Log(10) virus inactivation was calculated comparing treatment results to virus control titer.

RESULTS

Bleach and acid-based disinfectants inactivate FCV in 1 minute. Inactivation of FCV by alcohol and quaternary actives depends on how these actives are formulated as disinfectants. Actives and extreme pH are determined predictive of efficacy. Ethanol and quaternary compounds formulated at appropriate concentration and alkaline pH inactivates FCV in 1-minute contact.

CONCLUSION

Acid cleaners, ethanol, and quaternary compounds formulated at appropriate concentration and pH can be fast-acting antimicrobial choices and alternatives to bleach for the consumer and health care providers to use to inactivate FCV, a surrogate for norovirus, and protect against this important pathogen.

Efficacy of disinfectants and hand sanitizers against avian respiratory viruses

Disinfectants play a major role in the control of animal diseases by decontaminating the farm environment. We evaluated the virucidal efficacy of nine commonly used disinfectants on a nonporous surface contaminated experimentally with avian metapneumovirus (aMPV), avian influenza virus, or Newcastle disease virus (NDV). Phenolic compounds and glutaraldehyde were found to be the most effective against all three viruses. Quaternary ammonium compounds were effective against aMPV but not against the other two viruses. In addition, efficacy of commercially available hand sanitizers was evaluated on human fingers contaminated with aMPV and NDV. All three hand sanitizers tested were found to be effective against both viruses within 1 min of application on fingers.

Reducing absenteeism from gastrointestinal and respiratory illness in elementary school students: a randomized, controlled trial of an infection-control intervention

BACKGROUND

Students often miss school because of gastrointestinal and respiratory illnesses. We assessed the effectiveness of a multifactorial intervention, including alcohol-based hand-sanitizer and surface disinfection, in reducing absenteeism caused by gastrointestinal and respiratory illnesses in elementary school students.

METHODS

We performed a school-based cluster-randomized, controlled trial at a single elementary school. Eligible students in third to fifth grade were enrolled. Intervention classrooms received alcohol-based hand sanitizer to use at school and quaternary ammonium wipes to disinfect classroom surfaces daily for 8 weeks; control classrooms followed usual hand-washing and cleaning practices. Parents completed a preintervention demographic survey. Absences were recorded along with the reason for absence. Swabs of environmental surfaces were evaluated by bacterial culture and polymerase chain reaction for norovirus, respiratory syncytial virus, influenza, and parainfluenza 3. The primary outcomes were rates of absenteeism caused by gastrointestinal or respiratory illness. Days absent were modeled as correlated Poisson variables and compared between groups by using generalized estimating equations. Analyses were adjusted for family size, race, health status, and home sanitizer use. We also compared the presence of viruses and the total bacterial colony counts on several classroom surfaces.

RESULTS

A total of 285 students were randomly assigned; baseline demographics were similar in the 2 groups. The adjusted absenteeism rate for gastrointestinal illness was significantly lower in the intervention-group subjects compared with control subjects. The adjusted absenteeism rate for respiratory illness was not significantly different between groups. Norovirus was the only virus detected and was found less frequently on surfaces in intervention classrooms compared with control classrooms (9% vs 29%).

CONCLUSIONS

A multifactorial intervention including hand sanitizer and surface disinfection reduced absenteeism caused by gastrointestinal illness in elementary school students. Norovirus was found less often on classroom surfaces in the intervention group. Schools should consider adopting these practices to reduce days lost to common illnesses.

Virucidal activity of a quaternary ammonium compound disinfectant against feline calicivirus: a surrogate for norovirus

BACKGROUND

Norovirus, formerly known as Norwalk virus, is an important cause of gastroenteritis outbreaks in hospitals, food services, schools, and cruise ships. Infection control practices by using disinfectants to eliminate noroviruses from surfaces and environmental samples reduce the morbidity and spread of virus outbreaks. There are not many commercial disinfectants effective against norovirus. Noroviruses cannot be cultivated in vitro. However, feline calicivirus can be used as a surrogate to determine disinfectant efficacy against noroviruses. Feline calicivirus was used in a virucidal effectiveness test protocol as a surrogate for norovirus to determine the virucidal efficacy of R-82, a quaternary ammonium compound disinfectant cleaner.

METHODS

Feline calicivirus suspensions containing at least 5% fetal bovine serum were dried on carriers and treated with 1:256 dilutions of R-82 disinfectant in water, with a hardness of 400 ppm as calcium carbonate, for 10 minutes. Hypochlorite concentrations of 100 +/- 10 and 1,000 +/- 10 ppm, respectively, were also analyzed as internal control standards. After contact period, the test agents were neutralized with 2 mL of appropriate neutralizer, and mixtures were scraped from carrier surfaces with a cell scraper. Selected dilutions of the neutralized inoculum/test agent mixtures were added to cultured cell monolayers of appropriate host cells. Postincubation, the infectious feline calicivirus was scored microscopically by observing virus-specific cytopathic effects produced by replicating infectious virus. The performance criterion was a minimum of 4-log(10) reduction in cytopathic effects of feline calicivirus.

RESULTS

After a 10-minute contact time, formulation R-82 diluted 1:256 showed a 6.6- and 6.4-log(10) reductions in cytopathic effects of feline calicivirus during initial and confirmatory testing, respectively, demonstrating complete inactivation of the virus. A hypochlorite solution of 1,000 ppm exhibited similar log(10) reductions to the quaternary ammonium disinfectant, demonstrating the reproducibility of the protocol.

CONCLUSION

Formulation R-82, a quaternary ammonium compound, is a 1-step disinfectant cleaner, which exhibited virucidal activity against feline calicivirus suspensions dried on hard surface carriers. Surfaces are vectors for virus transmission during outbreaks by transferring the virus to people or other environmental surfaces. Therefore, treatment of contaminated surfaces with formulation R-82 will optimize disinfection of noncritical and critical surfaces in health care institutions, reducing the possibility of virus transmission during outbreaks.

Efficacy of three ethanol-based hand rubs against feline calicivirus, a surrogate virus for norovirus

We investigated the efficacy of three ethanol-based hand rubs (Sterillium Virugard, 95% ethanol; Sterillium Rub, 80% ethanol; Desderman N, 75.1% ethanol) against feline calicivirus (FCV), the surrogate virus for norovirus, on artificially contaminated hands of healthy volunteers. The ASTM E 1838-02 standard was used. Experiments were controlled with 70% ethanol and 70% propan-1-ol which were previously found to have maximal efficacy against FCV. In the first step, three different organic loads (5% fetal bovine serum, 5% faecal suspension and the tripartite ASTM load) were compared. A significant influence of the type of organic load was found (P<0.001, ANOVA). In the second step, the hand rubs were investigated with a 5% faecal suspension as a challenging organic load. The hand rub based on 95% ethanol was more effective than those based on 70% ethanol (mean log10 reduction factor: 2.17 vs. 1.56; P=0.17) and 70% propan-1-ol (mean RF: 1.63 vs. 0.95; P=0.0003). The hand rub based on 80% ethanol was also more effective than those based on 70% ethanol (mean RF: 1.25 vs. 1.03: P=0.20) and 70% propan-1-ol (mean RF: 1.43 vs. 1.09; P=0.03). The hand rub based on 75.1% ethanol was less effective than those based on 70% ethanol (mean RF: 1.07 vs. 1.27; P=0.47) and 70% propan-1-ol (mean RF: 0.78 vs. 0.97; P=0.35). Based on our data, ethanol has superior efficacy against FCV than propan-1-ol. In addition, a higher ethanol concentration in three commercially available hand rubs was associated with better efficacy against FCV.

Feline infectious disease control in shelters

No single factor determines whether a population remains healthy or disease rages out of control. All host and environmental factors taken together provide a number of tools to protect the vulnerable feline shelter population,however. A well-conceived infectious disease control program contributes to improved public perception, increased adoptions, and a healthier feline population within the shelter and in the community in general.

Emerging waterborne pathogens: can we kill them all?

The rapid emergence of Cryptosporidium parvum and Escherichia coli 0157:H7 have created a threat to the drinking water industry and there is a growing need to develop a strategy for recognizing potential emerging waterborne pathogens. Globalization of trade, changing population demographics and changes in treatment technology have been driving factors in the emergence of these new pathogens. An understanding of disinfectant action and microbial resistance to treatment processes is needed to better identify those pathogens likely to be of greatest concern. Recent research on microbial resistance to treatment and disinfection demonstrates that the microbial surface structure and composition and the nature of the genome are key to determining the potential for waterborne transmission of emerging pathogens.

An outbreak of virulent systemic feline calicivirus disease

OBJECTIVE

To describe clinical and epidemiologic features of an outbreak of feline calicivirus (FCV) infection caused by a unique strain of FCV and associated with a high mortality rate and systemic signs of disease, including edema of the face or limbs.

DESIGN

Observational study. Animals-54 cats naturally infected with a highly virulent strain of FCV.

PROCEDURE

Information was collected on outbreak history, clinical signs, and characteristics of infected and exposed cats.

RESULTS

A novel strain of FCV (FCV-Kaos) was identified. Transmission occurred readily via fomites. Signs included edema and sores of the face and feet. Mortality rate was 40%, and adults were more likely than kittens to have severe disease (odds ratio, 9.56). Eleven (20%) cats had only mild or no clinical signs. Many affected cats had been vaccinated against FCV. Viral shedding was documented at least 16 weeks after clinical recovery.

CONCLUSIONS AND CLINICAL RELEVANCE

Outbreaks of highly virulent FCV disease are increasingly common. Strains causing such outbreaks have been genetically distinct from one another but caused similar disease signs and were resistant to vaccination. All cats with suspicious signs (including upper respiratory tract infection) should be handled with strict hygienic precautions. Sodium hypochlorite solution should be used for disinfection following suspected contamination. All exposed cats should be isolated until negative viral status is confirmed. Chronic viral shedding is possible but may not be clinically important. This and similar outbreaks have been described as being caused by hemorrhagic fever-like caliciviruses, but hemorrhage is uncommonly reported. Virulent systemic FCV infection is suggested as an alternative description.

Update on feline calicivirus: new trends

In addition to being important upper respiratory tract pathogens of cats, FCVs are increasingly reported as a cause of a highly contagious febrile hemorrhagic syndrome. Strains causing this syndrome are genetically different from the vaccine strain and other nonhemorrhagic FCV isolates. They apparently differ from one outbreak to another. The syndrome is characterized variably by fever; cutaneous edema and ulcerative dermatitis; upper respiratory tract signs; anorexia; occasionally icterus, vomiting, and diarrhea; and a mortality that approaches 50%. Adult cats tend to be more severely affected than kittens, and vaccination does not appear to have a significant protective effect. Rapid recognition of the disease through identification of clinical signs and appropriate testing, followed by strict institution of disinfection, isolation, and quarantine measures, are essential to prevent widespread mortality resulting from the infection.

The virucidal spectrum of a high concentration alcohol mixture

The virucidal spectrum of a high concentration alcohol mixture (80% ethanol and 5% isopropanol) was determined for a broad series of lipid-enveloped (LE) and non-lipid-enveloped (NLE) viruses covering all relevant blood-borne viruses. LE viruses were represented by human immunodeficiency virus (HIV), bovine viral diarrhoea virus (BVDV), a specific model virus for hepatitis C virus (HCV), pseudorabies virus (PRV), and vaccinia virus. For the NLE viruses hepatitis A virus, canine parvovirus (a model for human parvovirus B19), and reovirus type 3 (Reo-3) were used. PRV, vaccinia, and Reo-3 served as general model viruses. The alcohol mixture was spiked with 5% (v/v) virus, mixed and tested for residual virus after 5 min treatment. Complete clearance (reduction by a factor of >10(6)) was observed for LE viruses, whereas incomplete to insignificant clearance (ranging from no reduction up to a maximum factor of 10(4)) was found for NLE viruses. In a second series of spiking experiments using the LE viruses BVDV, HIV, and PRV, complete clearance (reduction by a factor of >10(6)) was found after 20 s treatment. These data strongly suggest that treatment with a high concentration alcohol mixture has a high virucidal potential in particular for the blood-borne LE-viruses HIV, hepatitis B virus, and HCV. Such mixtures are well suited for rapid and frequent disinfection in dental practice being non-hazardous and non-toxic.

Virucidal efficacy of four new disinfectants

Virucidal efficacy was evaluated for four recently available disinfectants: chlorine dioxide, potassium peroxymonosulfate, a quaternary ammonium compound, and citricidal (grapefruit extract). Sodium hypochlorite (3%) and tap water were used as positive and negative controls respectively. Feline herpesvirus, feline calicivirus, and feline parvovirus were exposed to the manufacturers' recommended dilutions of the evaluated disinfectants. Both chlorine dioxide and potassium peroxymonosulfate completely inactivated the three viruses used in this study. These disinfectants can aid in controlling nosocomial transmission of viruses with less of the deleterious effects of sodium hypochlorite. The quaternary ammonium compound evaluated in this study and citricidal were not effective against feline calicivirus and feline parvovirus.

Efficacy of commonly used disinfectants for the inactivation of calicivirus on strawberry, lettuce, and a food-contact surface

Norwalk and Norwalk-like viruses (NLVs) are important causes of foodborne gastroenteritis in restaurant-related outbreaks. Efficacy of common disinfection methods against these viruses on food-contact surfaces and fresh produce is not known partially because of their nonculturability. Seven commercial disinfectants for food-contact surfaces and three sanitizers for fruits and vegetables were tested against cultivable feline calicivirus (FCV). Disks of stainless steel, strawberry, and lettuce were contaminated with known amounts of FCV. The disinfectants were applied at one, two, and four times the manufacturer's recommended concentrations for contact times of 1 and 10 min. The action of disinfectant was stopped by dilution, and the number of surviving FCVs was determined by titration in cell cultures. An agent was considered effective if it reduced the virus titer by at least 3 log10 from an initial level of 10(7) 50% tissue culture infective dose. None of the disinfectants was effective when used at the manufacturer's recommended concentration for 10 min. Phenolic compounds, when used at two to four times the recommended concentration, completely inactivated FCV on contact surfaces. A combination of quaternary ammonium compound and sodium carbonate was effective on contact surfaces at twice the recommended concentration. Rinsing of produce with water alone reduced virus titer by 2 log10. On artificially contaminated strawberry and lettuce, peroxyacetic acid and hydrogen peroxide was the only effective formulation when used at four times the manufacturers' recommended concentration for 10 min. These findings suggest that FCV and perhaps NLVs are very resistant to commercial disinfectants. However, phenolic compounds at two to four times their recommended concentrations appear to be effective at decontaminating environmental surfaces and may help control foodborne outbreaks of calicivirus in restaurants.

Effects of chlorine, iodine, and quaternary ammonium compound disinfectants on several exotic disease viruses

The effects of three representative disinfectants, chlorine (sodium hypochlorite), iodine (potassium tetraglicine triiodide), and quaternary ammonium compound (didecyldimethylammonium chloride), on several exotic disease viruses were examined. The viruses used were four enveloped viruses (vesicular stomatitis virus, African swine fever virus, equine viral arteritis virus, and porcine reproductive and respiratory syndrome virus) and two non-enveloped viruses (swine vesicular disease virus (SVDV) and African horse sickness virus (AHSV)). Chlorine was effective against all viruses except SVDV at concentrations of 0.03% to 0.0075%, and a dose response was observed. Iodine was very effective against all viruses at concentrations of 0.015% to 0.0075%, but a dose response was not observed. Quaternary ammonium compound was very effective in low concentration of 0.003% against four enveloped viruses and AHSV, but it was only effective against SVDV with 0.05% NaOH. Electron microscopic observation revealed the probable mechanism of each disinfectant. Chlorine caused complete degeneration of the viral particles and also destroyed the nucleic acid of the viruses. Iodine destroyed mainly the inner components including nucleic acid of the viruses. Quaternary ammonium compound induced detachment of the envelope of the enveloped viruses and formation of micelle in non-enveloped viruses. According to these results, chlorine and iodine disinfectants were quite effective against most of the viruses used at adequately high concentration. The effective concentration of quaternary ammonium compound was the lowest among the disinfectants examined.

Inactivation of feline calicivirus, a Norwalk virus surrogate

Norwalk and Norwalk virus-like particles (NVLPs) [also known as small round structured viruses (SRSVs)] are members of the family Caliciviridae and are important causes of gastroenteritis in humans. Little is known about their survival in the environment or the disinfection procedures necessary to remove them from contaminated settings. As NVLPs cannot be grown in tissue culture, survival studies require the use of a closely related cultivable virus. This study assesses the survival of the surrogate feline calicivirus (FCV) after exposure to commercially available disinfectants and a range of environmental conditions. Disinfectants tested included glutaraldehyde, iodine, hypochlorite, a quaternary ammonium-based product, an anionic detergent and ethanol. Complete inactivation of FCV required exposure to 1000 ppm freshly reconstituted granular hypochlorite, or 5000 ppm pre-reconstituted hypochlorite solution. Glutaraldehyde and the iodine-based product effectively inactivated FCV whereas the quaternary ammonium product, detergent and ethanol failed to completely inactivate the virus. The stability of FCV in suspension and in a dried state was assessed after exposure to 4 degrees C, room temperature (20 degrees C) and 37 degrees C. With increasing temperature, the stability of FCV was found to diminish both in suspension and in the dried state. FCV in the dried state did not survive for one day at 37 degrees C. This study provides a basis for establishing guidelines for disinfection protocols to decrease the spread of NVLPs in a community setting.