Evaluation of the Residual Disinfection Effects of Commonly Used Skin Disinfectants against Viruses: An Innovative Contact Transmission Control Method

Factors determining the resection ability of snares in cold snare polypectomy: Construction of an ex vivo model for accurately evaluating resection ability

OBJECTIVES

Cold snare polypectomy (CSP)-dedicated snares (DSs) may have a higher resection ability than conventional snares. However, a model that can accurately and objectively evaluate and compare the resection ability of each snare has yet to be determined, and characteristics of snare parts that increase resection ability remain unknown. Therefore, we elucidated DSs' resection ability and all characteristics of the parts required for acquiring high resection ability.

METHODS

An ex vivo model for evaluating resection ability was generated using human colons obtained from forensic autopsy specimens. The force required to resect a 15 mm wide human colonic mucosa (FRR) was measured using this model; if the FRR is small, the resection ability is high. Next, after measuring the stiffness of each snare part, the correlation between the stiffness and resection ability was analyzed.

RESULTS

The force required to resect using SnareMaster Plus, Micro-Tech Cold Snare, Captivator Cold, Exacto Cold Snare, or Captivator II was 13.6 ± 1.0, 12.5 ± 1.2, 7.4 ± 1.2, 6.5 ± 1.0, and 28.7 ± 3.7 N, respectively. All DSs had significantly lower FRR than the conventional snare (Captivator II) and had higher resection ability (P < 0.001). A negative correlation was found between FRR and sheath or wire spindle stiffness, with correlation coefficients of 0.72 (P = 0.042) or 0.94 (P < 0.001), respectively. Moreover, 1 × 7 type wire rings had significantly higher friction coefficients than 1 × 3 type wire rings (P < 0.002).

CONCLUSION

Sheath and wire spindle stiffness should be increased to increase resection ability; 1 × 7 type wire rings may be suitable for CSP-snare parts.

Evaluation of Environmental Stability and Disinfectant Effectiveness for Human Coronavirus OC43 on Human Skin Surface

The environmental stability of human coronavirus OC43 (HCoV-OC43) on the surface of human skin and the effectiveness of disinfectant against HCoV-OC43, which are important to prevent contact transmission, have not been clarified in previous studies. Using previously generated models, we evaluated HCoV-OC43 stability and disinfection effectiveness. Then we compared the results with those for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The median survival time of HCoV-OC43 on the surface of human skin was 24.6 h (95% confidence interval, 19.7 to 29.6 h), which was higher than that of SARS-CoV-2 (10.8 h). Although the in vitro disinfectant effectiveness evaluation showed that HCoV-OC43 has a higher ethanol resistance than SARS-CoV-2, HCoV-OC43 on the skin surface was completely inactivated by a minimum of 50% ethanol within 5 s (the log reduction values were >4.0). Moreover, 1.0% chlorhexidine gluconate and 0.2% benzalkonium chloride showed relatively high disinfectant effectiveness, and the log reduction values when these disinfectants were applied for 15 s were >3.0. HCoV-OC43 is highly stable on the skin surface, which may increase the risk of contact transmission. Although HCoV-OC43 has relatively high ethanol resistance, appropriate hand hygiene practices with current alcohol-based disinfectants sufficiently reduce the risk of contact transmission. IMPORTANCE This study revealed the environmental stability of HCoV-OC43 and disinfectant effectiveness against HCoV-OC43, which had not been demonstrated in previous studies. HCoV-OC43 is highly stable on the surface of human skin, with a survival time of approximately 25 h. High stability of HCoV-OC43 may increase the risk of contact transmission. Furthermore, the in vitro disinfectant effectiveness evaluation showed that HCoV-OC43, which is classified as an envelope virus, has a relatively high ethanol resistance. This finding suggests that disinfectant effectiveness may vary greatly depending on the virus and that each virus targeted for infection control should be evaluated individually. HCoV-OC43 on the skin surface was rapidly inactivated by 50% ethanol, which suggests that appropriate hand hygiene practices with current alcohol-based disinfectants can sufficiently reduce the risk of HCoV-OC43 contact transmission.

Disinfection and decontamination in the context of SARS-CoV-2-specific data

Given the high transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as witnessed early in the coronavirus disease 2019 (COVID-19) pandemic, concerns arose with the existing methods for virus disinfection and decontamination. The need for SARS-CoV-2-specific data stimulated considerable research in this regard. Overall, SARS-CoV-2 is practically and equally susceptible to approaches for disinfection and decontamination that have been previously found for other human or animal coronaviruses. The latter have included techniques utilizing temperature modulation, pH extremes, irradiation, and chemical treatments. These physicochemical methods are a necessary adjunct to other prevention strategies, given the environmental and patient surface ubiquity of the virus. Classic studies of disinfection have also allowed for extrapolation to the eradication of the virus on human mucosal surfaces by some chemical means. Despite considerable laboratory study, practical field assessments are generally lacking and need to be encouraged to confirm the correlation of interventions with viral eradication and infection prevention. Transparency in the constitution and use of any method or chemical is also essential to furthering practical applications.

Differences in environmental stability among SARS-CoV-2 variants of concern: Both Omicron BA.1 and BA.2 have higher stability

Objectives

The increased infectivity and transmissibility of SARS-CoV-2 variants of concern (VOCs) could cause significant human and economic damage. Hence, understanding their characteristics is crucial to control infection. We evaluated the environmental stability of the Wuhan strain and all VOCs (Alpha, Beta, Gamma, Delta, Omicron BA.1, and Omicron BA.2 variants) on plastic and human skin surfaces and their disinfection efficacy.

Methods

To evaluate environmental stability, residual virus titres on plastic and human skin surfaces were measured over time. Their survival time and half-life were calculated using regression analysis. The effectiveness of ethanol-based disinfectants at different concentrations was determined by in vitro and ex vivo evaluations.

Results

On plastic and skin surfaces, the Alpha, Beta, Delta, and Omicron variants exhibited approximately two-fold longer survival times than the Wuhan strain; the Omicron variants had the longest survival time. The median survival times of the Wuhan strain and the Alpha, Beta, Gamma, Delta, and Omicron (BA.1 and BA.2) variants on human skin surface were 8.6, 19.6, 19.1, 11.0, 16.8, 21.1, and 22.5 h, respectively. The in vitro evaluation showed that the Wuhan strain and the Alpha, Beta, Gamma, Delta, and Omicron (BA.1 and BA.2) variants were completely inactivated within 15 s by 32.5%, 35%, 35%, 32.5%, 35%, 40%, and 40% ethanol, respectively. However, all viruses on human skin were completely inactivated by exposure to 35% ethanol for 15 s.

Conclusions

SARS-CoV-2 VOCs, especially the Omicron variants, have higher environmental stability than the Wuhan strain, increasing their transmission risk and contributing to their spread.

The Efficacy of Common Household Cleaning Agents for SARS-CoV-2 Infection Control

The COVID-19 pandemic caused by SARS-CoV-2 is having devastating effects on a global scale. Since common household disinfectants are often used to minimise the risk of infection in the home and work environment, we investigated the ability of some of these products to inactivate the virus. We tested generic brands of vinegar, bleach, and dishwashing detergent, as well as laboratory-grade acetic acid, sodium hypochlorite, and ethanol. Assays were conducted at room temperature (18–20 °C, 40% relative humidity), and two time points were used to reflect a quick wipe (30 s) and a brief soak (5 min). Vinegar, and its active ingredient, acetic acid, were completely ineffective at virus inactivation even when exposed to the virus at 90% v/v (a final concentration equivalent to 3.6% v/v acetic acid). In contrast, ethanol was capable of inactivating the virus at dilutions as low as 40% v/v. Dishwashing detergent effectively rendered SARS-CoV-2 inactive when diluted 100-fold (1% v/v). Bleach was found to be fully effective against SARS-CoV-2 at 0.21 g/L sodium hypochlorite after a 30 s exposure (1/200 dilution of commercial product). Given reports of infectious virus recovered from the surface of frozen packaging, we tested the persistence of infectiousness after multiple freeze-thaw cycles and found no change in infectious SARS-CoV-2 titre after seven freeze-thaw cycles. These results should help inform readers of how to effectively disinfect surfaces and objects that have potentially been contaminated with SARS-CoV-2 using common household chemicals.