Quantitative Suspension Test Research Articles

Variable sensitivity of clinical Candida auris strains to Biocides: implications for infection control in Healthcare Settings

PurposeCandida auris, a multidrug-resistant yeast, poses significant challenges in healthcare settings due to its ability to form biofilms and resistance to common disinfectants. Understanding its susceptibility to biocides used in hospital disinfection practices is crucial for infection control. We investigated the biocide sensitivity of eight clinical C. auris strains from different patients and one reference strain (CDC B11903) using the biocide activity tests.MethodsSpecies identification was confirmed through MALDI-TOF MS, while clade differentiation and phylogenetic classification were determined via whole-genome sequencing. Biofilm formation was assessed using the MTT assay. Antifungal susceptibilities were tested according to CLSI standards. The effectiveness of biocides, including chlorine, chlorhexidine, and benzalkonium chloride, was evaluated through broth microdilution following CLSI standards and quantitative suspension and carrier tests, following EN standards.ResultsAll clinical strains were identified as clade 1, and the reference strain as clade 4, with all exhibiting biofilm formation. Clade 1 strains showed resistance to fluconazole, with MIC values ranging from 8 to 32 µg/ml, while being susceptible to other antifungals. Broth microdilution MIC assays for biocides demonstrated that all strains exhibited resistance to benzalkonium chloride. Chlorine and chlorhexidine showed variable efficacy, dependent on concentration and environmental cleanliness. Alcohol-based hand sanitizers demonstrated effectiveness against C. auris from the first minute of application.ConclusionThe study highlights the variable susceptibility of C.auris to different biocides, underscoring the challenge in eradicating this pathogen from healthcare environments. Our findings advocate for the careful selection of disinfectants in hospital settings, emphasizing the need for high-concentration chlorine and chlorhexidine solutions to combat C. auris, even in especially clean environments.

Antiviral activity of povidone-iodine gargle and mouthwash solution against Enterovirus A71, Coxsackieviruses A16, A10 and A6.

Hand, Foot and Mouth Disease (HFMD), a highly contagious viral disease common among infants and young children, is primarily caused by Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CVA16). Nonetheless, emerging enteroviruses, such as CV-A10 and CV-A6, have also caused widespread outbreaks globally, in part due to the absence of effective antiviral therapies, and the high personto-person transmission rate. Person-to-person transmission is usually through fecal-oral or oral-oral routes, and sometimes via droplets. As the oral cavity is a primary site for early virus infection and replication, controlling oral viral shedding can mitigate the risk of transmission through this route. Povidone-iodine (PVP-I), a widely used antiseptic, has shown broad-spectrum antimicrobial properties but antiviral studies against HFMD-causing enteroviruses are limited, especially for CV-A10 and CVA6. Our study demonstrated that a 1% PVP-I solution (final concentration of 0.5%) exhibited virucidal activity against EV-A71, CV-A16, CV-A10, and CV-A6. All seven EV-A71 isolates and five CV-A16 isolates showed a significant virus titer reduction after a 1-minute incubation, while five CV-A10 isolates and two CV-A6 isolates required a 5-minute incubation to achieve this. The virucidal activity was confirmed through the EN14476:2013+A2:2019 virucidal quantitative suspension test, wherein all four viruses were completely inactivated after a 30-minute incubation with PVP-I at 37°C under both clean and dirty conditions. Western blot analysis suggested that PVP-I could affect the VP1 structural proteins of EV-A71. Our results suggest that PVP-I could serve as a potential virucidal agent to reduce the risk of person-to-person transmission of HFMD.

Intravitreal chlorhexidine for sterilizing the vitreous cavity in an animal model of bacterial endophthalmitis

Purpose To evaluate the efficacy and safety of intravitreal chlorhexidine (CHX) for sterilising the vitreous cavity in bacterial endophthalmitis. Methods For in-vitro experiments, full-thickness retina explants were harvested from freshly enucleated pig eyes. Six-millimeter circular sensory retina patches were then incubated in varying concentrations of CHX (0.625-800 µg/mL) for 24 hours. Retinal cell viability was determined at the end of the incubation period with a live-dead assay. The bactericidal effects of the tested CHX concentrations were determined using a quantitative suspension test on Staphylococcus epidermidis. The safety of CHX was also tested by injecting varying doses of CHX (50-400 µg/mL) into the vitreous cavity of albino rabbits followed by flash electroretinography (ERG) and light microscopy. The bactericidal effect of the non-toxic CHX doses was determined using the rabbit model of endophthalmitis created by injecting 3000 CFU/0.1 mL of Staphylococcus epidermidis. Results In vitro concentrations of CHX greater than 6.25 µgr/mL exerted a bactericidal effect, while concentrations of CHX less than 200 µg/mL did not impair retinal cell viability. Intravitreal concentrations of CHX between 20-100 µg/mL were adequate to sterilise the infected rabbit vitreous cavity in the animal model. No significant functional or anatomical deleterious effect was observed with ERG or light microscopy. Conclusion CHX can sterilise the vitreous cavity in an animal model of bacterial endophthalmitis without impairing retinal cell viability. Our results encourage further research for clinical use of chlorhexidine in treatment of bacterial endophthalmitis.

Antiviral activity of Nigella sativa oil against two SARS-CoV-2surrogates in vitro as a dietary product

Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is primarily transmitted via aerosol and droplets, but environmental surfaces or potentially contaminated foods may contribute to further viral transmission. Nigella sativa seed (black cumin seed) oil possesses various biological activities against bacteria, fungi, parasites, orviruses. Objectives: This study aimed to explore black cumin seed oil (BSO) with anti-SARS-CoV-2 activities using bovine coronavirus (BCoV) and human coronavirus (HCoV) OC43 as surrogates. Methods and Results: BSO was tested at 1-100 mL/L concentrations for cytotoxicity towards human rectal tumor (HRT-18G) cells and 0.1-10 mL/L for efficacy against BCoV and HCoV OC43 in suspension. Two coronaviruses were separately mixed with BSO suspension and incubated for various times (0, 15, 30, 45, and 60 min) at 4, 23, and 37°C. The virus titerreduction was determined by median tissue culture infectious dose (TCID50) assay with HRT-18G cells as the host. BSO concentrations of 1-20 mL/L exhibited low cytotoxicity (<10%) towards HRT-18G cells. The inactivation of coronaviruses by BSO was concentration-, temperature-, and exposure time-dependent. At 37°C, BSO reduced 2.0 logs of BCoV and3.0 logs of HCoV OC43 in 60 min, respectively. Specifically, half maximal effective concentration (EC50) of BSO at 4, 23, and 37°C after the 1-h exposure was 4.28, 3.06, and 0.87 mL/L against BCoV, respectively, and 0.61, 0.61 and 0.48 mL/L against HCoV OC43, respectively. Moreover, BSO didn’t affect the attachment of BCoV and HCoV OC43 into host cells. Conclusion: Our findings on the inhibition activity of BSO against SARS-CoV-2 surrogates suggested the potential use of this natural product in mitigating SARS-CoV-2 infection. Our results also suggest that HCoV OC43 may be a more appropriate surrogate for SARS-CoV-2 to screen antiviral dietary products. Keywords: Nigella sativa, SARS-CoV-2 surrogates, antiviral activity, quantitative suspension test, dietary supplement

The scar-reducing effect of a novel chitosan gel: an in vivo study.

Scar tissue formation, as a normal part of wound healing, initiates in the proliferation phase, continues after the remodelling phase, and may cause an unpleasant appearance or disruption in normal functioning. This study investigated the effects of a topical gel on acute wound healing and reducing scars in a rat model. ChitoScar (ChitoTech Company, Iran), a commercial scar-reducing gel based on chitosan, was analysed for antibacterial and antiviral activity through a quantitative suspension test. Its cytotoxic effect was investigated, and then irritation and delayed-type hypersensitivity tests were carried out on rabbits through direct application of the gel. Furthermore, the effect of the chitosan-based gel on wound healing and scar tissue formation was studied in rats with an acute wound in two groups: the treatment group (topical application of the chitosan-based gel); and the control group (without treatment). Histopathological examination was carried out based on the inflammatory cells, collagen fibre, keratinocytes and fibroblasts. Analysis revealed that the chitosan-based gel had no cytotoxicity and caused no erythema, oedema, local or other systemic adverse response. Wound healing occurred earlier in the treatment group, which was a result of a significant increase in re-epithelialisation, angiogenesis, fibroblast population and collagen fibre thickness (p<0.05). In the treatment group, wounds healed completely after 21 days and scars totally disappeared after 28 days, while in the control group, wound healing remained incomplete with distinct scar tissue. The results demonstrated the positive effect of the chitosan-based gel on the duration and quality of the wound healing process, as well as minimising the scar tissue formation in this in vivo study.

Virucidal activity of a plant-oil-based oral rinse against respiratory viruses

Respiratory viruses have been reported to infect the salivary glands and the throat, which are potential reservoirs for virus replication and transmission. Therefore, strategies to reduce the amount of infective virus particles in the oral mucous membranes could lower the risk of transmission. In this study, the viral inactivation capacity of a plant oil-based oral rinse (Salviathymol) was evaluated in comparison to chlorhexidine (Chlorhexamed FORTE) using a quantitative suspension test according to EN 14476. Salviathymol efficiently inactivated severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), respiratory syncytial virus (RSV) and two influenza strains to undetectable levels, highlighting its potential as preventive measure to lower transmission of respiratory viruses.

Evaluation of a microscale quantitative suspension test to determine the bactericidal and yeasticidal activity of glutaral - one step to improve sustainability in disinfectant testing.

To evaluate a newly developed microscale quantitative suspension test compared to the existing standard suspension test using determination of the bactericidal and yeasticidal activity of glutaral as one step to improve the sustainability of disinfectant testing. The testing principles of the quantitative suspension test according to VAH method 9 (comparable to EN 13727) was used as a standard suspension test using 8.0 mL product test solution, 1.0 mL organic load and 1.0 mL test suspension. In addition, a micro-scale suspension test was performed in 96-well plates with 160 µL product test solution, 20 µL organic load and 20 µL test suspension. S. aureus ATCC 6538, P. aeruginosa ATCC 15442 and C. albicans ATCC 10231 were test organisms. Glutaral was tested at concentrations of 0.05%, 0.1%, 0.2% and 0.3% with exposure times of 1, 5 and 15 min. Polysorbate 80 (30 g/L), lecithin (9 g/L), L-histidine (1 g/L) and glycine (10 g/L) were used as validated neutralizers. After serial dilution of the disinfectant-neutralizer-mixture, plates were incubated for 48 h at 36°C (bacteria) or 72 hours at 30°C (C. albicans) and colony forming units (cfu) counted. The lg reduction was calculated as the difference between the results of the water control and the disinfectant at the end of the exposure time. All experiments were done in triplicate under clean conditions. Means of lg reduction were compared with the unpaired t-test, p<0.05 was considered to be significant. Sufficient bactericidal activity according the VAH test requirements of at least 5 lg was found with both methods in 16 data sets of 24 data sets in total, and insufficient bactericidal activity of less than 5 lg was found with both methods in 7 data sets. In one data set, the mean lg reduction was above 5 lg with the microscale method and <5 lg with the VAH method, with no significant difference between the data sets (p=0.3096; 0.2% glutaral, 1 min, P. aeruginosa). A sufficient yeasticidal activity of at least 4 lg was found with both methods in one data set, an insufficient yeasticidal activity of less than 4 lg was found with both methods in 8 data sets. With one exception, no significant differences were detected between the two methods below the efficacy threshold. The microscale quantitative suspension test proved to provide results similar to those of VAH method 9 when the bactericidal and yeasticidal activity of glutaralwas evaluated, with 32 out of 33 evaluations yielding consistent results in terms of efficacy. Its suitability should be confirmed with additional bacterial species, additional biocidal active substances and in other laboratories.

Virucidal activity of chlorine dioxide in combination with acetic acid or citric acid and a surfactant, in presence of interfering substances, against polio-, adeno- and murine norovirus in suspension-, carrier- and four-field tests.

The aim of the study was to investigate whether the virucidal effectiveness of chlorine dioxid against adenovirus and murine norovirus can be improved by combining it with carboxylic acids and surfactants. The virucidal efficacy against polio-, adeno- and murine norovirus has been tested in presence of interfering substances in the quantitative suspension test according to EN 14476, the carrier test without mechanical action according to EN 16777, and in the four-field test according to EN 16615.Three chlorine-dioxide-based surface disinfectants were tested: a two-component cleaning disinfectant concentrate for large surfaces, a ready-to-use (RTU) foam, and an RTU gel. Cleaning and disinfecting preparations based on chlorine dioxide, applied at various concentrations, in combination with acetic acid or citric acid and surfactants, are virucidally active against polio-, adeno-, and norovirus after an exposure time of 5 minutes in presence of interfering substances.

Evaluating the antimicrobial efficacy of long-lasting hand sanitizers on skin

The microbicidal efficacy of hand sanitizer formulations is usually measured through standardized quantitative suspension tests and fingerpad tests; these cannot evaluate long-lasting formulations or are impractical due to biological risks, high cost, or time required for testing. With increased numbers of long-lasting microbicidal activity claims of commercially available hand sanitizers, alternative testing strategies are required. To explore the use of a standardized ex-vivo pig skin model to reproducibly measure long-lasting efficacy of an alcohol-free hand sanitizer formulation. The microbicidal efficacy of an alcohol-free hand sanitizer was tested against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, and the enveloped virus SARS-CoV-2 with quantitative suspension tests (EN13727 and EN14476) with a contact time of 5min. The product was then tested over a 6h period using an ex-vivo pig skin model with a modified version of PAS 2424 to simulate the impact of skin abrasion. Quantitative suspension tests yielded a >5 log10 reduction for all organisms tested within a 5min contact time. Pig skin tests showed reduced but consistent efficacy at all time points and indicated no significant impact of abrasion on efficacy. The use of the ex-vivo pig skin model provides a potentially viable and convenient model system to test long-lasting hand sanitizer formulations, providing a path for sustainable hand sanitizer formulation claims of activity on skin.

Virucidal activity of oral, hand, and surface disinfectants against respiratory syncytial virus

Respiratory syncytial virus (RSV) is known as a major cause of respiratory tract infection in adults and children. Human to human transmission occurs via droplets as well as direct and indirect contact (e.g. contaminated surfaces or hands of medical staff). Therefore, applicable hygiene measures and knowledge about viral inactivation are of utmost importance. Here, we evaluated the virucidal efficacy of oral rinses specifically designed for children, WHO-recommended hand rub formulations and ethanol as well as 2-propanol against RSV in a quantitative suspension test (EN14476). Furthermore, we assessed the stability of RSV on stainless steel discs and investigated its inactivation by different surface disinfectants (EN16777). We observed that all tested oral rinses except one reduced infectious viral titres to the lower limit of quantification. The two WHO-recommended hand rub formulations as well as 30% ethanol and 2-propanol completely abolished the detection of infectious virus. Infectious RSV could still be recovered after several days on stainless steel discs. However, RSV could efficiently be inactivated by all tested surface disinfectants based on alcohol, aldehyde, or hydrogen peroxide. In conclusion, oral rinses, all tested hand rub formulations as well as surface inactivation reagents were sufficient for RSV inactivation in vitro.

Comparison of the Efficiency of Selected Disinfectants against Planktonic and Biofilm Populations of Escherichia coli and Staphylococcus aureus.

The aim of this study is to compare the efficacy of selected food disinfectants on planktonic populations of Staphylococcus aureus and Escherichia coli and on the same microorganisms (MOs) incorporated in a biofilm. Two disinfectants were used for treatment: peracetic acid-based disinfectant (P) and benzalkonium chloride-based disinfectant (D). Testing of their efficacy on the selected MO populations was performed using a quantitative suspension test. The standard colony counting procedure was used to determine their efficacy on bacterial suspensions in tryptone soy agar (TSA). The germicidal effect (GE) of the disinfectants was determined based on the decimal reduction ratio. For both MOs, 100% GE was achieved at the lowest concentration (0.1%) and after the shortest exposure time (5 min). Biofilm production was confirmed with a crystal violet test on microtitre plates. Both E. coli and S. aureus showed strong biofilm production at 25 °C with E. coli showing significantly higher adherence capacity. Both disinfectants show a significantly weaker GE on 48 h biofilms compared to the GE observed after application of the same concentrations on planktonic cells of the same MOs. Complete destruction of the viable cells of the biofilms was observed after 5 min of exposure to the highest concentration tested (2%) for both disinfectants and MOs tested. The anti-quorum sensing activity (anti-QS) of disinfectants P and D was determined via a qualitative disc diffusion method applied to the biosensor bacterial strain Chromobacterium violaceum CV026. The results obtained indicate that the disinfectants studied have no anti-QS effect. The inhibition zones around the disc therefore only represent their antimicrobial effect.

Inactivation kinetics of benzalkonium chloride and ethanol-based hand sanitizers against a betacoronavirus and an alphacoronavirus

Hand hygiene is critical to lower the potential for the spread of SARS-CoV-2 and other infectious agents by direct contact. When running water and soap are not available for hand hygiene, ethanol-based hand sanitizers are currently the recommended standard of care [1-3]. Though recently published data showed comparable invitro effectiveness of benzalkonium chloride (BAK)-based and ethanol-based hand sanitizers against SARS-CoV-2 virus, a paucity of peer-reviewed data on the effectiveness of these formulations against other types of infective coronaviruses remains. This work assessed human coronavirus HCoV-229E (genus Alphacoronavirus) concurrently with SARS-CoV-2, Isolate USA-WA1/2020 (genus Betacoronavirus) to fill this gap. The test was conducted according to EN14476:2013-A2:2019 [EN14476] Quantitative Suspension Test for the Evaluation of Virucidal Activity in the Medical Area [4]. Two BAK-based hand sanitizers, five ethanol-based hand sanitizers, and an 80% ethanol reference formulation were tested for antiviral activity against SARS-CoV-2 and HCoV-229E at 15- and 30- second contact times. Both SARS-CoV-2 and HCoV-229E were reduced by greater than 4.00-log10 within 15 seconds of contact. Virus decay constants (k) following first-order kinetics were similar for BAK and ethanol-based formulations against both test viruses. The SARS-CoV-2 results reported herein mirrored previous data reported by Herdt etal. (2021). BAK and ethanol hand sanitizer formulations inactivate SARS-CoV-2 and HCoV-229E at similar rates. This data supports previously published effectiveness data for both chemistries and indicates that additional coronavirus strains and variants would demonstrate similar inactivation trends.

Comparative Virucidal Activities of Essential Oils and Alcohol-Based Solutions against Enveloped Virus Surrogates: In Vitro and In Silico Analyses.

The large-scale use of alcohol (OH)-based disinfectants to control pathogenic viruses is of great concern because of their side effects on humans and harmful impact on the environment. There is an urgent need to develop safe and environmentally friendly disinfectants. Essential oils (EOs) are generally recognized as safe (GRAS) by the FDA, and many exhibit strong antiviral efficacy against pathogenic human enveloped viruses. The present study investigated the virucidal disinfectant activity of solutions containing EO and OH against DENV-2 and CHIKV, which were used as surrogate viruses for human pathogenic enveloped viruses. The quantitative suspension test was used. A solution containing 12% EO + 10% OH reduced > 4.0 log10 TCID50 (100% reduction) of both viruses within 1 min of exposure. In addition, solutions containing 12% EO and 3% EO without OH reduced > 4.0 log10 TCID50 of both viruses after 10 min and 30 min of exposure, respectively. The binding affinities of 42 EO compounds and viral envelope proteins were investigated through docking analyses. Sesquiterpene showed the highest binding affinities (from -6.7 to -8.0 kcal/mol) with DENV-2 E and CHIKV E1-E2-E3 proteins. The data provide a first step toward defining the potential of EOs as disinfectants.

The Investigation of the Efficacy of Some Antiseptics and Disinfectants to Vancomycin-Resistant Enterococci

Disinfection of contaminated material, surface and body parts with appropriate substances is one of the most effective practices in preventing the infection-colonization of Vancomycin-Resistant Enterococci (VRE). In this study, 1/10 and 1/100 dilutions of 5% sodium hypochlorite, 4% concentration of chlorhexidine gluconate and 0.1% and 0.5% concentrations of Akacid plus’s efficacy against VRE strains at 1, 5, 15 and 30 minutes was tested. Sixty-nine vancomycin-resistant E. faecium strains isolated from different body samples between 2012 and 2014 were included in the study. The BD Phoenix 100® fully automated system was used for the identification of strains and detection of vancomycin resistance. Quantitative Suspension Test method EN 1276 (March 2010) was used to evaluate the bactericidal activities of chemical disinfectants and antiseptics used in European Union countries in the investigation of disinfectant susceptibility of VRE strains. Five log10 decrease (105) in the number of bacteria in the initial test suspension between the number of bacteria after using the disinfectant indicates that the disinfectant is effective. In this study, it has been determined that a 1/10 dilution of 5% sodium hypochlorite (bleach) is the most effective disinfectant on VREs in all minutes and conditions. Effectiveness of 1/100 dilution of bleach has a significant decrease in dirty conditions. Akacid plus was not effective on all strains in any contact times we tested. It has been observed that Akacid plus is the disinfectant least affected by the changes in environmental conditions in all minutes. Chlorhexidine gluconate (4%) was ineffective in clean and dirty conditions in just 1 minute, while from the 5th minute, its effectiveness was found to be statistically at the same level as the 1/10 dilution of bleach. There was no decrease in the activities of chlorhexidine due to the changing environmental conditions. In conclusion, it has been determined that a 1/10 dilution of 5% sodium hypochlorite (bleach) is the most effective disinfectant on VREs in all minutes and conditions, but dirty environmental conditions cause a significant decrease in the effectiveness of sodium hypochlorite. In addition, it was observed that the effectiveness of all disinfectants and antiseptics on VREs increased as the contact time with the substances increased.

Use of the pour plate technique in tuberculocidal efficacy testing according to EN 14348 – a comparative study

Effective disinfection strategies are essential to prevent the spread of Mycobacterium tuberculosis. Tuberculocidal efficacy of disinfectants can be demonstrated by testing disinfectants in in-vitro tests, such as the well-established quantitative suspension test EN 14348 using Mycobacterium terrae as a surrogate organism in European disinfectant testing. In other European standard tests, such as EN 13727 and EN 13624, use of the pour plate technique is well established; however, in EN 14348, the spread plate technique alone is considered. Comparative experiments according to EN 14348 with M.terrae were conducted using a peracetic-acid-based disinfectant. Either the pour plate technique or the spread plate technique was used for cultivation. Differences in colony size and morphology were observed when comparing the growth of M.terrae on pour plates compared with spread plates. However, no significant differences in biocidal efficacy data were obtained when applying either spread plates or pour plates in the quantitative suspension test described in EN 14348 under both clean and dirty conditions.

Assessment of the bacteriological quality and efficacy of two hand sanitizers sold within Ilishan-Remo Community of Ogun State, Nigeria

Background. Hand sanitizers have been recognized as an effective means of reducing bacterial load and transmission. It is needful to periodically assess the bacteriological status of individual products due to batch variation. Aim. This study was designed to assess the bacteriological quality and efficacy of two hand sanitizers sold within the Ilishan-Remo community of Ogun State, Nigeria, amidst the COVID-19 pandemic. Methodology. Samples of two brands of hand sanitizers were procured and assessed using standard bacteriological methods, including Sterility test, Surface viable count, Gram-stain, Motility test, Biochemical tests, Quantitative suspension test, and Agar diffusion test. Data were analyzed with paired-samples T-Test using Statistical Package for the Social Sciences -Version 20.0 (SPSS-20.0) to assess for significant variation between the effectiveness of the two hand sanitizers. P-values &lt;0.05 was considered significant. Results. The study's outcome showed the satisfactory bacteriological quality of both hand sanitizers tested. However, the mean bacterial load was not significantly reduced after sterilization using both hand sanitizers. The hand sanitizers' bactericidal activity was also considered unsatisfactory since the Log reduction was less than 5. Brand B hand sanitizer proved to be more potent than Brand A at the contact time. Each of the products displayed varying inhibitory activities against the bacterial isolates. Conclusion. The study highlighted the need to periodically assess the bacteriological quality and efficacy of hand sanitizers to guarantee the general safety of the end users and ensure proper infection control.

Evaluation and comparison of three virucidal agents on inactivation of Nipah virus

Modern human activity is profoundly changing our relationship with microorganisms with the startling rise in the rate of emerging infectious diseases. Nipah virus together with Ebola virus and SARS-CoV-2 are prominent examples. Since COVID-19 and the West African Ebola virus disease outbreak, different chemical disinfectants have been developed for preventing the direct spread of viruses and their efficacy has also been evaluated. However, there are currently no published efficacy studies for the chemical disinfection of Nipah virus. In this study, the virucidal efficacy of three disinfectants (Micro-Chem Plus detergent disinfectant cleaner, FWD and Medical EtOH) against Nipah virus was evaluated in quantitative suspension tests including. Our results showed that the > 4 log reduction achieved for all products in inactivating Nipah virus in 15 s. Even, 19% ethanol was able to inactivate Nipah virus when applied for at least 8 min contact time. Comparative analysis displayed virucidal efficacy of each of the evaluated disinfectants against SARS-CoV-2, Ebola virus and Nipah virus, with only minor differences in working concentrations and contact times required for complete inactivation. We expect that our study can assist in decontamination in healthcare settings and high level biosafety laboratories and can be beneficial to control for emerging enveloped viruses.

Efficacy of disinfectants for inactivation of Ebola virus in suspension by integrated cell culture coupled with real-time RT–PCR

Ebola virus can be transmitted by contact with environmental surfaces (fomites) contaminated with secretions and excretions from infected individuals. Due to their potential to cause a public health emergency and the absence of efficacious drugs and vaccines, a crucial intervention may involve the use of an effective virucidal agent for disinfecting contaminated surfaces. To evaluate the virucidal efficacy of three disinfectants against Ebola virus: Micro-Chem Plus detergent disinfectant cleaner (MCP), FWD, and ethanol; in suspension tests according to the Technical Standard for Disinfection of China. All products at different concentrations were tested with application times ranging from 15s to 8min by using a quantitative suspension test, and a comparative inactivation analysis was performed. A reduction in the virus titre of ≥4 log10 was regarded as evidence of virucidal activity. MCP and FWD, which contain dual quaternary ammonium compounds, are highly effective at inactivating the Ebola virus within 15s of contact time, despite a slight difference between them at lower concentrations. In agreement with the literature, our results confirmed the excellent virucidal activity of medical ethanol for Ebola virus, which can reduce viral titres to background levels within 15s at a concentration of 38% (v/v). These three disinfectants display sufficient inactivation efficacy for the Ebola virus at reasonably short contact times, which may be practically achieved in the field. The use of these disinfectants for decontamination in healthcare settings and laboratories could mitigate the risk of Ebola virus transmission.

Efficacy of octenidine against emerging echinocandin-, azole- and multidrug-resistant Candida albicans and Candida glabrata

Infections due to Candida species represent a serious threat to healthcare facilities. Only a few classes of antifungal agents are available, and the rapid emergence of (multi)drug resistance eliminates effective treatment options for successful patient outcome. Topically applied antiseptics may represent a suitable tool for infection control and local therapy. This study aimed to investigate the in vitro efficacy of the widely used antiseptic octenidine (OCT) against clinical isolates of emerging azole-, echinocandin- and multi-resistant Candida albicans and Candida glabrata. The antifungal activity of different concentrations of OCT ranging from 0.001% to 0.05% and of OCT-containing ready-to-use products was determined against well-characterised (multidrug) resistant C. albicans and C. glabrata isolates, including susceptible wild-type strains. Quantitative suspension tests were performed under "clean conditions" (0.3 g/L bovine serum albumin) and under "dirty conditions" (3 g/L albumin+3 mL/L defibrinated sheep blood) as well as various contact times (30 s, 1 min, 2 min) according to EN13624:2013. Even in the presence of a high organic load, pure OCT at 0.05% and a contact time of 30 s was fully effective for all Candida strains, with growth kinetics indicating a time- and concentration-dependent activity. Importantly, commercially available OCT-based products achieved the required reduction of ≥4 log10 for all Candida isolates under the most challenging dirty conditions within two minutes, which makes them suitable for routine clinical use. These results encourage consideration of the well-tolerated antiseptic molecule OCT in the eradication of emerging (multidrug) resistant C. albicans and C. glabrata.

Hepatitis E virus is highly resistant to alcohol-based disinfectants

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis worldwide and is mainly transmitted via the fecal-oral route or through consumption of contaminated food products. Due to the lack of efficient cell culture systems for the propagation of HEV, limited data regarding its sensitivity to chemical disinfectants are available. Consequently, preventive and evidence-based hygienic guidelines on HEV disinfection are lacking. We used a robust HEV genotype 3 cell culture model which enables quantification of viral infection of quasi-enveloped and naked HEV particles. For HEV genotype 1 infections, we used the primary isolate Sar55 in a fecal suspension. Standardized quantitative suspension tests using end point dilution and large-volume plating were performed for the determination of virucidal activity of alcohols (1-propanol, 2-propanol, ethanol), WHO disinfectant formulations and 5 different commercial hand disinfectants against HEV. Iodixanol gradients were conducted to elucidate the influence of ethanol on quasi-enveloped viral particles. Naked and quasi-enveloped HEV was resistant to alcohols as well as alcohol-based formulations recommended by the WHO. Of the tested commercial hand disinfectants only 1 product displayed virucidal activity against HEV. This activity could be linked to phosphoric acid as an essential ingredient. Finally, we observed that ethanol and possibly non-active alcohol-based disinfectants disrupt the quasi-envelope structure of HEV particles, while leaving the highly transmissible and infectious naked virions intact. Different alcohols and alcohol-based hand disinfectants were insufficient to eliminate HEV infectivity with the exception of 1 commercial ethanol-based product that included phosphoric acid. These findings have major implications for the development of measures to reduce viral transmission in clinical practice. Hepatitis E virus (HEV) showed a high level of resistance to alcohols and alcohol-based hand disinfectants. The addition of phosphoric acid to alcohol was essential for virucidal activity against HEV. This information should be used to guide improved hygiene measures for the prevention of HEV transmission.