Use of a mixture of surrogates for infectious bioagents in a standard approach to assessing disinfection of environmental surfaces

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.

Disinfectant testing for veterinary and agricultural applications: A review

Disinfectants for veterinary and livestock use, plus skin antiseptics, are critical elements for the control of infectious agents, including zoonotic and antimicrobial-resistant micro-organisms, in managed animal species. Such agents impact animal welfare, economic performance and human health. Testing of disinfectants is needed for safety, efficacy and quality control. The present review examines the principal types of test (carrier, suspension, surface and field) that have been developed or attempted, plus the features inherent in the respective tests, particularly with respect to variability. Elements of testing that have to be controlled, or which can be manipulated, are discussed in the context of real-world scenarios and anticipated applications. Current national and international testing regimes are considered, with an emphasis on the UK, continental Europe and North America, and with further detail provided in the Supporting Information. Challenges to disinfectant efficacy include: the nature of the biological targets (bacteria, fungi, yeasts, spores, viruses and prions), the need for economical and safe working concentrations, the physical and chemical nature of contaminated surfaces, constraints on contact times and temperatures, the presence of organic soil and other barrier or neutralising substances (including biofilms), and thoroughness of pre-cleaning and disinfectant application. The principal challenges with veterinary disinfectant testing are the control of test variability, and relating test results to likely performance in variable field conditions. Despite some ambitions to develop standardised field tests for disinfectants, aside from skin antiseptic trials the myriad problems such tests pose with respect to cost, reproducibility and generalisability remain intractable.

A systematic review of chlorine-based surface disinfection efficacy to inform recommendations for low-resource outbreak settings

Background

Infectious diseases can be transmitted via fomites (contaminated surfaces/objects); disinfection can interrupt this transmission route. However, disinfection guidelines for low-resource outbreak settings are inconsistent and not evidence-based.

Methods

A systematic review of surface disinfection efficacy studies was conducted to inform low-resource outbreak guideline development. Due to variation in experimental procedures, outcomes were synthesized in a narrative summary focusing on chlorine-based disinfection against 7 pathogens with potential to produce outbreaks in low-resource settings (Mycobacterium tuberculosis, Vibrio cholerae, Salmonella spp., hepatitis A virus, rotavirus, norovirus, and Ebola virus).

Results

Data were extracted from 89 laboratory studies and made available, including 20 studies on relevant pathogens used in combination with surrogate data to determine minimum target concentration × time (“CT”) factors. Stainless steel (68%) and chlorine-based disinfectants (56%) were most commonly tested. No consistent trend was seen in the influence of chlorine concentration and exposure time on disinfection efficacy. Disinfectant application mode; soil load; and surface type were frequently identified as influential factors in included studies.

Conclusions

This review highlights that surface disinfection efficacy estimates are strongly influenced by each study's experimental conditions. We therefore recommend laboratory testing to be followed by field-based testing/monitoring to ensure effectiveness is achieved in situ.

Comparison of a rapid detection fluorescence-based assay targeting tuberculocidal efficacy with EN 14348 and EN 14563

BACKGROUND

A rapid test system using fluorescent Mycobacterium terrae to evaluate the tuberculocidal efficacy of disinfectants has recently been published. Results were obtained in a significantly shorter time than was previously possible.

AIM

To compare the European Standard test system with the fluorescence assay and to validate the rapid test system, including particularly the quantitative suspension test.

METHODS

Quantitative suspension tests and quantitative carrier tests were carried out according to EN 14348 and EN 14563, respectively. Quantitative carrier tests and subsequent green fluorescent protein (GFP)-based determination of germicidal efficacy were carried out as described previously. A peracetic acid-based formulation was used as a test germicide.

FINDINGS

Testing of the germicide in the quantitative suspension test EN 14348 and in the quantitative carrier test EN 14563 revealed tuberculocidal efficacy at a concentration of 1% after 15 min contact time. Accordingly, data obtained from the fluorescence assay demonstrated that a germicide concentration of 1% was effective after 15 min, indicating no live mycobacteria following this treatment. Thus, identical in-use parameters for tuberculocidal efficacy were obtained either by applying the quantitative suspension and quantitative carrier tests EN 14348 and EN 14563 or by using the GFP-based rapid test system.

CONCLUSION

The GFP-based rapid test system compares well with the established European Standard test procedure including both phase 2, step 1 and phase 2, step 2 tests and provides a rapid and sensitive tool for testing germicides for relevant in-use concentrations and contact times.

Evaluation of disinfectant efficacy against multidrug-resistant bacteria: A comprehensive analysis of different methods

BACKGROUND

Multidrug-resistant gram-negative bacteria (MDR-GNB) constitute a threat to health care worldwide. Disinfectants are used to prevent and control the spread of MDR-GNB in a hospital setting but their efficacy might be impaired by bacterial mechanisms that may act on both antimicrobials and disinfectants. Determination of minimum inhibitory concentrations is mainly used to determine bacterial susceptibility against disinfectants, but practical tests on surfaces might be more suitable to predict in-use conditions. Our objective was to compare and evaluate 4 different methods widely used to assess surface disinfectant efficacy.

METHODS

The efficacy of benzalkonium chloride (BAC), peracetic acid (PAA), and ethanol (ETH) against multidrug-resistant Acinetobacter, Pseudomonas, and Klebsiella strains was assessed by minimum inhibitory concentration determinations, quantitative suspension tests, qualitative suspension tests, and carrier tests. Test results were compared to ascertain the most appropriate method.

RESULTS

ETH, PAA, and BAC were highly effective against MDR-GNB, but we observed marked differences in efficacious concentrations (up to 100-fold) as a function of the test method applied. Minimum inhibitory concentration determination was not reliable for evaluating susceptibility or resistance to BAC.

CONCLUSIONS

Surface tests should be used to determine bacterial susceptibility against disinfectants. Moreover, suitable guidelines are needed that allow for the standardization and comparison of bactericidal values obtained by different investigators.

Analysis of Acinetobacter baumannii survival in liquid media and on solid matrices as well as effect of disinfectants

BACKGROUND

Acinetobacter baumannii is a cause of healthcare-associated infections and has considerable potential to survive on inanimate hospital surfaces under hostile conditions (e.g. disinfection or desiccation).

AIM

To learn more about its survival strategy and capacity to persist in liquid media and on surfaces mimicking hospital environments.

METHODS

The effect of temperature, nutrient deprivation, permanence on inanimate surfaces, and exposure to disinfectants on the survival of four A. baumannii strains (ATCC 19606^T and three clinical isolates) was studied by monitoring the number of total and viable cells using fluorescent microscopy and of culturable cells by standard cultures.

FINDINGS

Bacterial survival was differentially affected by temperature (cells maintained at 20°C remained culturable at least within 30 days) and physical environment (desiccation favoured cell resistance to stress at 37°C). Moreover, persistence was associated with two adaptation patterns: one linked to entry into the viable but non-culturable state, whereas the other apparently followed a bust-and-boom model. During a study on the effect of disinfectant (commercial bleach and quaternary ammonium compounds), it was found that treatment with these antibacterial compounds did not eliminate A. baumannii populations and provoked the reduction of culturable populations, although a fraction of cells remained culturable.

CONCLUSION

The ability to persist for long periods on different surfaces, mimicking those usually found in hospitals, along with A. baumannii's capacity to survive after a disinfection process may account for the recurrent outbreaks in intensive care units.

Do we know how best to disinfect child care sites in the United States? A review of available disinfectant efficacy data and health risks of the major disinfectant classes

BACKGROUND

Children in child care settings have a high infectious burden. They are frequently exposed to sanitizing and disinfecting agents, whose toxicities have not been studied in these settings. Current guidance on the preferred disinfection agents for child care is vague.

METHODS

This article combines 2 different sources of information: the Environmental Protection Agency registration data on the efficacy of hospital-grade disinfectants and a review of the research on the toxicities of the most common of these disinfectants to summarize information that could be used for more evidence-based early care and education disinfection regulations and guidelines.

RESULTS

Coverage of these organisms varied both between disinfectant classes (defined by active ingredient), as well as within classes. The 3 most common active ingredients in the database-quaternary ammonias, bleaches, and hydrogen peroxides-had 251, 63, and 31 products, respectively. Quaternary ammonias and bleaches are both known asthmagens, with the potential for toxic gas release when mixed. Quaternary ammonias may also cause reproductive toxicity. Disinfectant-grade peroxides have relatively low inhalational toxicity.

CONCLUSIONS

A clear rationale is needed to establish policies for determining preferable disinfection products for use in child care settings, based on efficacy against relevant pathogens, toxicity, ease of use, and cost. When other factors are equal, the use of peroxide-based disinfectant products is recommended to minimize inhalational toxicity.

Persistence of Hepatitis A Virus in Fresh Produce and Production Environments, and the Effect of Disinfection Procedures: A Review

Although information is limited, it is evident that prolonged persistence of infectious Hepatitis A virus (HAV) is a factor in the transmission of the virus via fresh produce. Consequently, data on persistence of the virus on produce, and in environments relevant to production, such as soils, water and surfaces, are required to fully understand the dynamics of transmission of HAV via foods. Furthermore, information on effective disinfection procedures is necessary to implement effective post-harvest control measures. This review summarises current information on HAV persistence in fresh produce and on relevant disinfection procedures. On vegetables, HAV can remain infectious for several days; on frozen berries, it can persist for several months. HAV can remain infectious on surfaces for months, depending on temperature and relative humidity, and can survive desiccation. It can survive for several hours on hands. Washing hands can remove the virus, but further data are required on the appropriate procedure. Chlorination is effective in water, but not when HAV is associated with foodstuffs. Bleach and other sodium hypochlorite disinfectants at high concentrations can reduce HAV on surfaces, but are not suitable for use on fresh produce. There is only limited information on the effects of heating regimes used in the food industry on HAV. HAV is resistant to mild pasteurisation. Some food components, e.g. fats and sugars, can increase the virus' resistance to higher temperatures. HAV is completely eliminated by boiling. Quantitative prevalence data are needed to allow the setting of appropriate disinfection log reduction targets for fresh produce.

Effect of Surface Sampling and Recovery of Viruses and Non-Spore-Forming Bacteria on a Quantitative Microbial Risk Assessment Model for Fomites

Quantitative microbial risk assessment (QMRA) is a powerful decision analytics tool, yet it faces challenges when modeling health risks for the indoor environment. One limitation is uncertainty in fomite recovery for evaluating the efficiency of decontamination. Addressing this data gap has become more important as a result of response and recovery from a potential malicious pathogen release. To develop more accurate QMRA models, recovery efficiency from non-porous fomites (aluminum, ceramic, glass, plastic, steel, and wood laminate) was investigated. Fomite material, surface area (10, 100, and 900 cm(2)), recovery tool (swabs and wipes), initial concentration on the fomites and eluent (polysorbate 80, trypticase soy broth, and beef extract) were evaluated in this research. Recovery was shown to be optimized using polysorbate 80, sampling with wipes, and sampling a surface area of 10-100 cm(2). The QMRA model demonstrated, through a relative risk comparison, the need for recovery efficiency to be used in these models to prevent underestimated risks.

Inactivation Kinetics and Mechanism of a Human Norovirus Surrogate on Stainless Steel Coupons via Chlorine Dioxide Gas

Acute gastroenteritis caused by human norovirus is a significant public health issue. Fresh produce and seafood are examples of high-risk foods associated with norovirus outbreaks. Food contact surfaces also have the potential to harbor noroviruses if exposed to fecal contamination, aerosolized vomitus, or infected food handlers. Currently, there is no effective measure to decontaminate norovirus on food contact surfaces. Chlorine dioxide (ClO2) gas is a strong oxidizer and is used as a decontaminating agent in food processing plants. The objective of this study was to determine the kinetics and mechanism of ClO2 gas inactivation of a norovirus surrogate, murine norovirus 1 (MNV-1), on stainless steel (SS) coupons. MNV-1 was inoculated on SS coupons at the concentration of 10(7) PFU/coupon. The samples were treated with ClO2 gas at 1, 1.5, 2, 2.5, and 4 mg/liter for up to 5 min at 25°C and a relative humidity of 85%, and virus survival was determined by plaque assay. Treatment of the SS coupons with ClO2 gas at 2 mg/liter for 5 min and 2.5 mg/liter for 2 min resulted in at least a 3-log reduction in MNV-1, while no infectious virus was recovered at a concentration of 4 mg/liter even within 1 min of treatment. Furthermore, it was found that the mechanism of ClO2 gas inactivation included degradation of viral protein, disruption of viral structure, and degradation of viral genomic RNA. In conclusion, treatment with ClO2 gas can serve as an effective method to inactivate a human norovirus surrogate on SS contact surfaces.

Study of the virucidal potential of organic peroxyacids against norovirus on food-contact surfaces

This study was conducted to evaluate the efficacy of four different peroxyacids, namely peracetic (PAA), perpropionic (PPA), perlactic (PLA), and percitric (PCA) for inactivating viruses in suspension or attached to stainless steel or polyvinyl chloride surfaces. The test virus was a proxy for human norovirus, namely murine norovirus 1. Plaque-forming units in suspension (10(7) per mL) were treated with 50-1,000 mg L(-1) peroxyacid (equilibrium mixture of organic acid, hydrogen peroxide, peroxyacid, and water) for 1-10 min. Inactivation was measured by plaque assay. PAA and PPA were the most effective, with a 5 min treatment at 50 mg L(-1) being sufficient to reduce viral titer by at least 3.0 log10, whether the virus was in suspension or attached to stainless steel or polyvinyl chloride disks under clean or fouled conditions. Combinations of organic acid and hydrogen peroxide were found ineffective. Similar inactivation was observed in the case of virus in artificial biofilm (alginate gel). These short super-oxidizers could be used for safe inactivation of human noroviruses in water or on hard surfaces.

Pedicure-associated rapidly growing mycobacterial infection: an endemic disease

BACKGROUND

Pedicure-associated nontuberculous mycobacterial furunculosis has been reported in the setting of either outbreaks or sporadic case reports. The epidemiology of these infections is not well understood.

METHODS

Systematic surveillance for pedicure-associated nontuberculous mycobacterial furunculosis was conducted in 2 North Carolina counties from 1 January 2005 through 31 December 2008. A subset of implicated nail salons and control salons was inspected and sampled for nontuberculous mycobacteria.

RESULTS

Forty cases of suspected or confirmed pedicure-associated nontuberculous mycobacterial furunculosis were reported during the 4-year study period. Furunculosis incidence in the surveillance region was 1.00, 0.96, 0.83, and 0.89 cases per 100,000 population in 2005, 2006, 2007, and 2008, respectively. The responsible organisms primarily belonged to the Mycobacterium chelonae/abscessus group (30 [91%] of 33 isolates). Thirteen implicated salons and 11 control salons were visited and environmentally sampled. An assortment of nontuberculous mycobacteria was cultured from footbaths, but there was no association between the species distribution of the environmental isolates and implication of the salon in human infection. Evidence of suboptimal cleaning (visible debris or surface biofilms) was observed in at least 1 footbath for 11 of 13 implicated salons and 4 of 11 control salons (P = .032).

CONCLUSIONS

Pedicure-associated mycobacterial furunculosis was endemic in these 2 North Carolina counties during 2005-2008. Suboptimal footbath cleaning may have contributed to these infections, which suggests straightforward means of potential prevention. The relative rarity of this type of infection in the setting of nearly ubiquitous exposure to these pathogens suggests that as yet undefined host-specific or procedure-related factors may be involved in susceptibility to these infections.

Inactivation of coxsackievirus B4, feline calicivirus and herpes simplex virus type 1: unexpected virucidal effect of a disinfectant on a non-enveloped virus applied onto a surface

OBJECTIVE

To evaluate the effect of a disinfectant onto viruses in suspension on the one hand and applied onto a surface on the other.

METHODS

A system combining flocked swabs to recover viruses dried onto stainless steel carriers and gel filtration to eliminate cytotoxic products has been developed to study the virucidal effect of a quaternary ammonium-based disinfectant towards herpes simplex virus type 1 (HSV-1), coxsackievirus B4 (CVB4) and feline calicivirus F9 (FCV). The recovery of FCV has been estimated by RT real-time PCR.

RESULTS

HSV-1, CVB4 and FCV had a titer over 10(4) TCID50 · ml(-1) after 2 h drying and were recovered from the carriers using flocked swabs. HSV-1 was inactivated in suspension and on stainless steel carriers by the disinfectant (a reduction factor of 4 and 2.83 log, respectively) whereas CVB4 was resistant. The reduction of infectious titer was moderate, 1.5 log in 30 min, when FCV was in suspension, whereas it was up to 4 log in 10 min when the virus was dried on a carrier. Dried FCV was efficiently recovered from carriers as demonstrated by RT real-time PCR.

CONCLUSION

A non-enveloped virus, FCV, applied on a surface, but not in suspension, was inactivated by a quaternary ammonium-based disinfectant. The resistance of viruses applied onto a surface to the effect of disinfectants should be investigated further.

The crucial role of wiping in decontamination of high-touch environmental surfaces: review of current status and directions for the future

The testing and label claims of disinfectants to wipe high-touch environmental surfaces rarely reflect their field use where contact times are in seconds with only microliters of the disinfectant deposited on a unit surface area. Therefore, such products must be properly assessed with mechanical/chemical action combined. We critically review current wipe test methods and propose future approaches.

Influence of temperature and organic load on chemical disinfection of Geobacillus steareothermophilus spores, a surrogate for Bacillus anthracis

This study evaluated the influence of temperature and organic load on the effectiveness of domestic bleach (DB), Surface Decontamination Foam (SDF), and Virkon in inactivating Geobacillus stearothermophilus spores, which are a surrogate for Bacillus anthracis spores. The spores were suspended in light or heavy organic preparations and the suspension was applied to stainless steel carrier disks. The dried spore inoculum was covered with the disinfectants and the disks were then incubated at various temperatures. At -20°C, the 3 disinfectants caused less than a 2.0 log10 reduction of spores in both organic preparations during a 24-h test period. At 4°C, the DB caused a 4.4 log10 reduction of spores in light organic preparations within 2 h, which was about 3 log10 higher than what was achieved with SDF or Virkon. In heavy organic preparations, after 24 h at 4°C the SDF had reduced the spore count by 4.5 log10, which was about 2 log10 higher than for DB or Virkon. In general, the disinfectants were most effective at 23°C but a 24-h contact time was required for SDF and Virkon to reduce spore counts in both organic preparations by at least 5.5 log10. Comparable disinfecting activity with DB only occurred with the light organic load. In summary, at temperatures as low as 4°C, DB was the most effective disinfectant, inactivating spores within 2 h on surfaces with a light organic load, whereas SDF produced the greatest reduction of spores within 24 h on surfaces with a heavy organic load.

The antimicrobial properties of cedar leaf (Thuja plicata) oil; a safe and efficient decontamination agent for buildings

Cedar leaf oil (CLO), derived from the Western red cedar, Thuja plicata, was evaluated as a safe and acceptable broad spectrum antimicrobial agent, with a view to its potential applications in buildings, including the alleviation of sick building syndrome. Various Gram-positive and Gram-negative human bacteria, and two fungal organisms, all known to be common environmental sources of potential infection, were selected and tested quantitatively, and all of them were found to be susceptible to CLO liquid and vapor. Bacterial spores and Aspergillus niger were sensitive, although less so than the vegetative bacteria. Similar tests with cultured human lung cells showed that continuous exposure to CLO vapor for at least 60 minutes was not toxic to the cells. Based on these results, CLO shows promise as a prospective safe, green, broad-spectrum anti-microbial agent for decontamination of buildings.