Surface Disinfection Method Research Articles

Nonthermal plasma‐generated ozone inhibits human coronavirus 229E infectivity on glass surface

AbstractOzone has been used for surface disinfection to contain bacterial, fungal, mold, and certain viral infections; however, the use of ozone generated from nonthermal plasma devices have not been thoroughly investigated for surface disinfection. Here, we aimed to determine the impact of nonthermal plasma‐generated ozone (PGO) on the coronavirus. Human coronavirus 229E was exposed to PGO and its infectivity was evaluated. PGO exposure of approximately 7 ppm reduced the viral titer after 4 h. Our results indicate that PGO exposure not only reduces the expression of the viral nucleocapsid gene and spike glycoprotein levels but may also stimulate the expression of the antiviral response gene in host cells. These findings can thus be useful to support existing surface disinfection methods.

Synergistic inactivation of Listeria and E. coli using a combination of erythorbyl laurate and mild heating and its application in decontamination of peas as a model fresh produce

We investigated the synergistic antimicrobial activity of erythorbyl laurate (EL) and mild heating co-treatment on the Gram-positive Listeria innocua and Gram-negative Escherichia coli O157:H7 bacteria. EL (2 mM) and mild heating (55 °C for 3 min) resulted in 3.1 and 0.5 log colony forming units (CFU)/mL reductions in the number of L. innocua, respectively, compared to a 6.4 log CFU/mL reduction induced by the combined treatment of EL and mild heating in saline. EL (10 mM) and mild heating (55 °C for 3 min) resulted in 1.3 and 0.7 log CFU/mL reductions in the number of E. coli O157:H7, respectively, compared to a 6.2 log CFU/mL reduction with the combined treatment in saline. EL, a membrane-active compound, showed a strong synergistic effect with mild heating, possibly due to enhanced disruption of the bacterial cell membrane. The synergistic antibacterial effect was evaluated using inoculated English peas (Pisum sativum) and this combined treatment (2 mM EL and mild heating against L. innocua and 10 mM EL and mild heating against E. coli O157:H7) resulted in more than 7 log reductions in the numbers of L. innocua and E. coli O157:H7, inoculated on the surface of fresh peas. The treatments did not show significant difference in the color or texture of treated peas compared to the non-treated controls. This is the first report illustrating synergistic activity of EL and mild heating for both the gram positive (L. innocua) and the gram negative (E. coli O157:H7) bacteria on food. Overall, this research will illustrate the development of more effective and rapid antibacterial surface disinfection method for application in the processing of minimally processed foods.

Treatment with dry hydrogen peroxide accelerates the decay of severe acute syndrome coronavirus-2 on non-porous hard surfaces

BackgroundDisinfection of contaminated or potentially contaminated surfaces has become an integral part of the mitigation strategies for controlling coronavirus disease 2019. Whilst a broad range of disinfectants are effective in inactivating severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), application of disinfectants has a low throughput in areas that receive treatments. Disinfection of large surface areas often involves the use of reactive microbiocidal materials, including ultraviolet germicidal irradiation, chlorine dioxide, and hydrogen peroxide vapor. Albeit these methods are highly effective in inactivating SARS-CoV-2, the deployment of these approaches creates unacceptable health hazards and precludes the treatment of occupied indoor spaces using existing disinfection technologies. In this study, the feasibility of using dry hydrogen peroxide (DHP) in inactivating SARS-CoV-2 on contaminated surfaces in large indoor spaces was evaluated.MethodsGlass slides were inoculated with SARS-CoV-2 and treated with DHP between 5 and 25 ppb for up to 24 hours. Residual infectious virus samples were eluted from three replicates at each time point and titrated in African green monkey VeroE6 cells.ResultsIn comparison with the observed relatively high stability of SARS-CoV-2 on contaminated glass slides (control group), residual infectious titers of glass slides inoculated with SARS-CoV-2 were significantly reduced after receiving 120 minutes of DHP treatment.ConclusionsThe accelerated decay of SARS-CoV-2 on contaminated glass slides suggests that treatment with DHP can be an effective surface disinfection method for occupied indoor spaces

A Systematic Review of Surface Contamination, Stability, and Disinfection Data on SARS-CoV-2 (Through July 10, 2020).

We conducted a systematic review of hygiene intervention effectiveness against SARS-CoV-2, including developing inclusion criteria, conducting the search, selecting articles for inclusion, and summarizing included articles. Overall, 96 268 articles were screened and 78 articles met inclusion criteria with outcomes in surface contamination, stability, and disinfection. Surface contamination was assessed on 3343 surfaces using presence/absence methods. Laboratories had the highest percent positive surfaces (21%, n = 83), followed by patient-room healthcare facility surfaces (17%, n = 1170), non-COVID-patient-room healthcare facility surfaces (12%, n = 1429), and household surfaces (3%, n = 161). Surface stability was assessed using infectivity, SARS-CoV-2 survived on stainless steel, plastic, and nitrile for half-life 2.3-17.9 h. Half-life decreased with temperature and humidity increases, and was unvaried by surface type. Ten surface disinfection tests with SARS-CoV-2, and 15 tests with surrogates, indicated sunlight, ultraviolet light, ethanol, hydrogen peroxide, and hypochlorite attain 99.9% reduction. Overall there was (1) an inability to align SARS-CoV-2 contaminated surfaces with survivability data and effective surface disinfection methods for these surfaces; (2) a knowledge gap on fomite contribution to SARS-COV-2 transmission; (3) a need for testing method standardization to ensure data comparability; and (4) a need for research on hygiene interventions besides surfaces, particularly handwashing, to continue developing recommendations for interrupting SARS-CoV-2 transmission.

Environmental Disinfection Strategies to Prevent Indirect Transmission of SARS-CoV2 in Healthcare Settings

(1) Introduction: The novel respiratory syndrome coronavirus 2 (SARS-CoV-2), also called coronavirus disease 2019 (COVID-19), is rapidly spreading in many countries and represents a public health emergency of international concern. The SARS-CoV-2 transmission mainly occurs from person-to-person via respiratory droplets (direct transmission route), leading to the onset of mild or severe symptoms or even causing death. Since COVID-19 is able to survive also on inanimate surfaces for extended periods, constituting an indirect transmission route, healthcare settings contaminated surfaces should be submitted to specific disinfection protocols. Our review aimed to investigate the existing disinfection measures of healthcare settings surfaces, preventing the nosocomial transmission of SARS-CoV-2. (2) Materials and Methods: We conducted electronic research on PubMed, Scopus, Science Direct, and Cochrane Library, and 120 items were screened for eligibility. Only 11 articles were included in the review and selected for data extraction. (3) Results: All the included studies proposed the use of ethanol at different concentrations (70% or 75%) as a biocidal agent against SARS-CoV-2, which has the capacity to reduce the viral activity by 3 log10 or more after 1 min of exposure. Other disinfection protocols involved the use of chlorine-containing disinfectant, 0.1% and 0.5% sodium hypochlorite, quaternary ammonium in combination with 75% ethanol, isopropyl alcohol 70%, glutardialdehyde 2%, ultraviolet light (UV-C) technology, and many others. Two studies suggested to use the Environmental Protection Agency (EPA)-registered disinfectants, while one article chooses to follow the WST-512-2016 Guidance of Environmental and Surfaces Cleaning, Disinfection and Infection Control in Hospitals. (4) Conclusion: Different surface disinfection methods proved to reduce the viral activity of SARS-CoV-2, preventing its indirect nosocomial transmission. However, more specific cleaning measures, ad hoc for the different settings of the healthcare sector, need to be formulated.

Surface deposited one-dimensional copper-doped TiO2 nanomaterials for prevention of health care acquired infections.

Bacterial infections acquired in healthcare facilities including hospitals, the so called healthcare acquired or nosocomial infections, are still of great concern worldwide and represent a significant economical burden. One of the major causes of morbidity is infection with Methicillin Resistant Staphylococcus aureus (MRSA), which has been reported to survive on surfaces for several months. Bactericidal activity of copper-TiO2 thin films, which release copper ions and are deposited on glass surfaces and heated to high temperatures, is well known even when illuminated with very weak UVA light of about 10 μW/cm2. Lately, there is an increased intrerest for one-dimensional TiO2 nanomaterials, due to their unique properties, low cost, and high thermal and photochemical stability. Here we show that copper doped TiO2 nanotubes produce about five times more ·OH radicals as compared to undoped TiO2 nanotubes and that effective surface disinfection, determined by a modified ISO 22196:2011 test, can be achieved even at low intensity UVA light of 30 μW/cm2. The nanotubes can be deposited on a preformed surface at room temperature, resulting in a stable deposition resistant to multiple washings. Up to 103 microorganisms per cm2 can be inactivated in 24 hours, including resistant strains such as Methicillin-resistant Staphylococcus aureus (MRSA) and Extended-spectrum beta-lactamase Escherichia coli (E. coli ESBL). This disinfection method could provide a valuable alternative to the current surface disinfection methods.

Comparison of surface disinfection method on frequently touched objects in dental clinic

Comparison of surface disinfection method on frequently touched objects in dental clinic

Inactivation of Salmonella enteritidis on shell eggs by coating with phytochemicals

Salmonella enteritidis (SE) is a major foodborne pathogen that causes human infections largely by consumption of contaminated eggs. The external surface of eggs becomes contaminated with SE from multiple sources, highlighting the need for effective egg surface disinfection methods. This study investigated the efficacy of three GRAS-status, phytochemicals, namely carvacrol (CR), eugenol (EG), and β-resorcylic acid (BR) applied as pectin or gum arabic based coating for reducing SE on shell eggs. White-shelled eggs, spot inoculated with a 5-strain mixture of nalidixic acid (NA) resistant SE (8.0 log CFU/mL) were coated with pectin or gum arabic solution containing each phytochemical (0.0, 0.25, 0.5, or 0.75%), and stored at 4°C for 7 days. SE on eggs was enumerated on days 0, 1, 3, and 7 of storage. Approximately 4.0 log CFU/egg of SE was recovered from inoculated and pectin or gum arabic coated eggs on day 0. All coating treatments containing CR and EG, and BR at 0.75% reduced SE to undetectable levels on day 3 (P <0.05). Results suggest that the aforementioned phytochemicals could effectively be used as a coating to reduce SE on shell eggs, but detailed studies on the sensory and quality attributes of coated eggs need to be conducted before recommending their use.

Purification and characterization of endophytic fungal strains from four different high value medicinal plants of Kashmir valley

This study was designed to isolate, purify and characterize endophytic fungi from four different high value medicinal plants of Kashmir valley as a possible source of bioactive secondary metabolites. A total of 14 morphologically different endophytic strains were isolated from the plants exploited for endophytes. All isolates were identified based on colony morphology, examination of spores and light microscopes. The endophytic fungi were successfully isolated from the plants using the surface disinfection method. The optimized parameters for the optimum growth of the endophytic fungi were obtained as temperature of 28C, potato dextrose broth medium and rpm at 180-200.

Purification of four strains of endophytic fungi from Astragalus and their optimized liquid fermentations

This study was designed to isolate endophytic fungi from A. mongholicus (growing in northeast China) to determine whether they can produce bioactive metabolites. Four strains of endophytic fungi (strains 16, 17, 23 and 75) were successfully isolated from A. mongholicus using the surface disinfection method. According to ITS-rDNA sequences analysis, strains 16 and 75 were identified as Fusarium oxysporum, and strains 17 and 23 were identified as Bionectria ochroleuca. We applied the Box-Behnken design (BBD) to optimize the liquid fermentation conditions and obtain the maximum cell dry weight (CDW) yield. Optimal parameters were obtained under the following experimental conditions: temperature of 28°C, potato dextrose agar (PDA) liquid medium of 80 mL and rotation speed of 150 rpm. The four isolated endophytic fungi did not produce astragalosides I–IV, flavonoids or polysaccharides. Isolation of additional species of endophytic fungi from A. mongholicus and determination of their capacity to produce biologically active substances are subjects in need of further research.

Microfungi associated with withering willow wood in ground contact near Syowa Station, East Antarctica for 40 years

Data are rather lacking on the diversity of microfungi associated with exotic plant substrates transported to continental Antarctica. We examined the diversity and species composition of microfungi associated with withering woody shoots of saplings of Salix spp. (willows) transplanted and in ground contact near Syowa Station, East Antarctica for more than 40 years. The willow saplings originated from Hokkaido, Northern Japan, and were experimentally transplanted in 1967–1968, but died within a few years. Dead willow shoots, unbranched and standing on bare ground for approximately 50 years, were used for the isolation of fungi with the surface disinfection method. A total of 43 isolates were retrieved from 32 (78 %) of the 41 shoots tested. The fungal isolates were classified into 18 molecular operational taxonomic units (MOTUs) based on the similarity of rDNA ITS sequences at the 97 % criterion. Leotiomycetes was the most common class in terms of the number of isolates and MOTUs, followed by Dothideomycetes, Sordariomycetes, and Eurotiomycetes. Molecular phylogenetic affinities suggested that the closest relatives of the MOTUs were saprobic and root-associated fungi. The result of the present study suggested that Cadophora luteo-olivacea is widespread in soils throughout Antarctica and likely indigenous.

Chemical disinfection of high-consequence transboundary animal disease viruses on nonporous surfaces

Disinfection is a critical part of the response to transboundary animal disease virus (TADV) outbreaks by inactivating viruses on fomites to help control infection. To model the inactivation of TADV on fomites, we tested selected chemicals to inactivate Foot and Mouth Disease virus (FMDV), African Swine Fever virus (ASFV), and Classical Swine Fever virus (CSFV) dried on steel and plastic surfaces. For each of these viruses, we observed a 2 to 3 log reduction of infectivity due to drying alone. We applied a modified surface disinfection method to determine the efficacy of selected disinfectants to inactivate surface-dried high-titer stocks of these three structurally different TADV. ASFV and FMDV were susceptible to sodium hypochlorite (500 and 1000 ppm, respectively) and citric acid (1%) resulting in complete disinfection. Sodium carbonate (4%), while able to reduce FMDV infectivity by greater than 4-log units, only reduced ASFV by 3 logs. Citric acid (2%) did not totally inactivate dried CSFV, suggesting it may not be completely effective for disinfection in the field. Based on these data we recommend disinfectants be formulated with a minimum of 1000 ppm sodium hypochlorite for ASFV and CSFV disinfection, and a minimum of 1% citric acid for FMDV disinfection.

Selection of a decontamination treatment for fresh Tuber aestivum and Tuber melanosporum truffles packaged in modified atmospheres

The objective of this study was to develop a surface disinfection method which, combined with modified atmosphere packaging (MAP), prolonged the shelf-life of Tuber aestivum and Tuber melanosporum truffles. T. aestivum was washed with sodium hypochlorite (500 ppm chlorine), hydrogen peroxide (5%) and ethanol (70%) alone or in combination with ultrasound (35 Hz) for 10 min at 4 °C. Dipping in ethanol 70% with ultrasound was found to be the most effective treatment, achieving 4 logarithmic reductions for pseudomonads, reductions greater than 2 logarithmic units for Enterobacteriaceae, lactic acid bacteria and molds and 1.5 logarithmic reductions for yeasts. Finally, both truffle species were decontaminated with the selected treatment, packaged with a microperforated film and stored at 4 °C for 28 days. In this situation the microbial counts and the sensory quality were maintained throughout storage and the shelf-life of both truffle species were prolonged to 28 days.

Evaluation of Treatments for Elimination of Foodborne Pathogens on the Surface of Leaves and Roots of Lettuce (Lactuca sativa L.)

Several outbreaks of Salmonella and Escherichia coli O157:H7 infections have been associated with consumption of leafy greens. Questions remain concerning the ability of these pathogens to become internalized within lettuce and spinach tissues. An effective validated surface disinfection method for lettuce is needed before factors affecting internalization of pathogens can be studied. The objective of this study was to develop a surface disinfection method for lettuce leaves and roots. Iceberg lettuce (Lactuca sativa L.) leaves cut into pieces (3 by 3 cm) and lettuce roots were inoculated by immersing in suspensions of five-strain mixtures of green fluorescent protein–labeled E. coli O157:H7, Salmonella, or Listeria monocytogenes at populations of 7 to 8 log CFU/ml for 10 min at 20 ± 1°C. Inoculated samples were placed in a laminar flow biosafety cabinet for 30 min before treating with disinfectants. Thirteen surface disinfection methods were compared for their efficacy in killing E. coli O157:H7 on lettuce leaf and root surfaces. E. coli O157:H7 initially at 5.8 or 6.8 log CFU/leaf piece or root was not detected by enumeration (<0.6 log CFU per leaf piece) on samples treated for 20 min with 10,000 μg/ml sodium hypochlorite (NaHClO) or in solutions containing ethanol and mercuric chloride (HgCl2). With all other methods, E. coli O157:H7 populations ranged from 2.8 to 4.4 CFU per leaf piece or root after treatment. Trends in leaf and root print and enrichment culture results were consistent with enumeration results. Dipping in 80% ethanol for 10 s followed by immersion in 0.1% HgCl2 for 10 min was determined to be the most effective surface disinfection method for inactivating E. coli O157:H7 on lettuce leaves and roots and was also validated for inactivating Salmonella and L. monocytogenes.

Survey of mycoflora and ochratoxin A in dried vine fruits from Argentina markets.

The aims of this work were to identify the mycoflora and to evaluate the natural occurrence of OA in dried vine fruits. Likewise, the capacity to produce OA by Aspergillus section Nigri was studied. Fifty samples of dried vine fruits were obtained from Mendoza and San Juan provinces. The surface disinfection method was used for mycoflora determination using the medium dichloran 18% glycerol agar (DG18) and dichloran Rose Bengal chloramphenicol agar (DRBC). Statistical analysis demonstrated that the species A. niger var. niger and Aspergillus niger var. awamori were isolated in higher frequency from black dried vine fruits from DRBC and DG18 media (P < 0.01). OA was found in 74% of the dried vine fruits samples. Sixty-two strains (28%) of Aspergillus section Nigri, were OA producers. In the species A. carbonarius the highest percentages of ochratoxigenic strains were detected (82.6%). The presence of ochratoxigenic strains of Nigri section in dried vine fruits suggests that they may be an important source of OA in this substrate. Dried vine fruits can also be an important source of OA people who consume large amounts. The dried vine fruits contamination with Aspergillus section Nigri and OA was significant.

Mycoflora and ochratoxin-producing strains of Aspergillus section Nigri in wine grapes in Argentina.

The aims of this work were to evaluate the mycoflora and to identify the species of Aspergillus with the potential to produce ochratoxin A (OA) from different wine grape varieties from Mendoza, Argentina. Likewise, the capacity to produce OA by Aspergillus section Nigri was studied. Fifty samples of wine grapes were obtained from a winery of Mendoza province, Argentina. The surface-disinfection method was used for mycoflora determination using the medium dichloran 18% glycerol agar (DG18). Alternaria, Aspergillus and Penicillium were identified at species level. OA production was tested in 63 strains belonging to section Nigri. Alternaria genus was the most frequent (80% of the samples) followed by Aspergillus (70%). Alternaria alternata was the only specie identified from the Alternaria genus, followed by A. niger var. niger, A. flavus among others. From Penicillium genus, P. crysogenum was the most frequent specie. From 63 strains of Aspergillus section Nigri, 41.3% were OA producers. The levels of produced toxin ranged from 2 to 24.5 ng ml-1 of culture medium. The presence of ochratoxigenic strains of Nigri section in this substrate suggests that they may be an important source of OA in grapes from tropical and subtropical zones. Therefore, the industry should work further to diminish the growth of these fungi and mycotoxins formation in grapes, with the aim to reduce OA content in wine products. The wine grape contamination with A. alternata and Aspergillus section Nigri was significant.

An improved surface disinfection method for shoot expiants fromIrisrhizomes infected with bacterial soft rot (Erwinia carotovorasubsp,carotovora)

SummaryThe standard method (protocol 1) for disinfecting shoot expiants used for initiation of plant tissue cultures failed when Iris rhizomes were infected with bacterial soft rot (Erwinia carotovora subsp, carotovora), Two new disinfection protocols were therefore developed, They involved keeping stock plants without irrigation for two months prior to excision of expiants; alcohol disinfection of the expiants prior to excision from the rhizome; dipping of the expiant in alcohol immediately after excision; soaking in 1 % (v/v) sodium hypochlorite (protocol 2) or saturated calcium hypochlorite (protocol 3); and soaking in mercuric chloride, With protocols 2 and 3 up to 90% and 62% respectively of expiants taken from infected Iris rhizomes showing soft-rot symptoms remained free of detectable microorganisms in vitro.