Efficacy of antimicrobial and anti-viral coated air filters to prevent the spread of airborne pathogens.

The COVID-19 pandemic has demonstrated the real need for mechanisms to control the spread of airborne respiratory pathogens. Thus, preventing the spread of disease from pathogens has come to the forefront of the public consciousness. This has brought an increasing demand for novel technologies to prioritise clean air. In this study we report on the efficacy of novel biocide treated filters and their antimicrobial activity against bacteria, fungi and viruses. The antimicrobial filters reported here are shown to kill pathogens, such as Candida albicans, Escherichia coli and MRSA in under 15 min and to destroy SARS-CoV-2 viral particles in under 30 s following contact with the filter. Through air flow rate testing, light microscopy and SEM, the filters are shown to maintain their structure and filtration function. Further to this, the filters are shown to be extremely durable and to maintain antimicrobial activity throughout the operational lifetime of the product. Lastly, the filters have been tested in field trials onboard the UK rail network, showing excellent efficacy in reducing the burden of microbial species colonising the air conditioning system.

The effectiveness of various gargle formulations and salt water against SARS-CoV-2.

The COVID-19 is difficult to contain due to its high transmissibility rate and a long incubation period of 5 to 14 days. Moreover, more than half of the infected patients were young and asymptomatic. Virus transmission through asymptomatic patients is a major challenge to disease containment. Due to limited treatment options, preventive measures play major role in controlling the disease spread. Gargling with antiseptic formulation may have potential role in eliminating the virus in the throat. Four commercially available mouthwash/gargle formulations were tested for virucidal activity against SARS-CoV-2 in both clean (0.3 g/l BSA) and dirty (0.3 g/l BSA + 3 mL/L human erythrocytes) conditions at time points 30 and 60 s. The virus was isolated and propagated in Vero E6 cells. The cytotoxicity of the products to the Vero E6 was evaluated by kill time assay based on the European Standard EN14476:2013/FprA1:2015 protocol. Virus titres were calculated as 50% tissue culture infectious dose (TCID50/mL) using the Spearman-Karber method. A reduction in virus titer of 4 log10 corresponds to an inactivation of ≥ 99.99%. Formulations with cetylperidinium chloride, chlorhexidine and hexitidine achieved > 4 log10 reduction in viral titres when exposed within 30 s under both clean and dirty conditions. Thymol formulations achieved only 0.5 log10 reduction in viral titres. In addition, salt water was not proven effective. Gargle formulations with cetylperidinium chloride, chlorhexidine and hexetidine have great potential in reducing SAR-CoV-2 at the source of entry into the body, thus minimizing risk of transmission of COVID-19.

Implementing daily chlorhexidine gluconate (CHG) bathing in VA settings: The human factors engineering to prevent resistant organisms (HERO) project.

BACKGROUND: Daily use of chlorhexidine gluconate (CHG) has been shown to reduce risk of healthcare-associated infections. We aimed to assess moving CHG bathing into routine practice using a human factors approach. We evaluated implementation in non-intensive care unit (ICU) settings in the Veterans Health Administration. METHODS: Our multiple case study approach included non-ICU units from 4 Veterans Health Administration settings. Guided by the Systems Engineering Initiative for Patient Safety, we conducted focus groups and interviews to capture barriers and facilitators to daily CHG bathing. We measured compliance using observations and skin CHG concentrations. RESULTS: Barriers to daily CHG include time, concern of increasing antibiotic resistance, workflow and product concerns. Facilitators include engagement of champions and unit shared responsibility. We found shortfalls in patient education, hand hygiene and CHG use on tubes and drains. CHG skin concentration levels were highest among patients from spinal cord injury units. These units applied antiseptic using 2% CHG impregnated wipes vs 4% CHG solution/soap. DISCUSSION: Non-ICUs implementing CHG bathing must consider human factors and work system barriers to ensure uptake and sustained practice change. CONCLUSIONS: Well-planned rollouts and a unit culture promoting shared responsibility are key to compliance with daily CHG bathing. Successful implementation requires attention to staff education and measurement of compliance.

Chlorhexidine gluconate does not result in epidermal microbiota dysbiosis in healthy adults.

BACKGROUND: Chlorhexidine gluconate (CHG) and other skin antiseptics are ubiquitous in healthcare settings and are routinely used to bathe patients' skin. The commensal epidermal microbiota is believed to provide colonization resistance and other benefits to the host; yet little is known regarding the long-term stability of the epidermal microbiota, and the impact of CHG bathing. We aimed to assess the influence of CHG exposure to the epidermal microbiota and evaluate the long-term stability of the epidermal microbiota. METHODS: The epidermal microbiota of 5 individuals was sampled using thorough swabbing of the calf, and characterized via 16S rRNA amplicon sequencing, prior to CHG bathing, and then at 30 minutes, 3 hours, 1 day, 3 days, and 7 days postbathing. Roughly 4 months later, samples were collected from the same 5 individuals, using an identical timeline but with no CHG exposure. RESULTS: The epidermal microbiota showed no greater change 30 minutes postexposure to CHG, than was observed in the same individuals during the recovery period, likely representing the normal sample-to-sample variability. Despite that variability, the epidermal microbiota evinced a remarkable degree of intrasubject stability, even over extended periods of time. CONCLUSION: We conclude that single applications of CHG cause minimal, if any, disruption of the epidermal microbiota, and that long-term effects of single applications of CHG on the epidermal microbiota are unlikely.

Disinfectant effectiveness against SARS-CoV-2 and influenza viruses present on human skin: model-based evaluation.

OBJECTIVES: Disinfection effectiveness against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on human skin remains unclear because of the hazards of viral exposure. An evaluation model, which has been previously generated using human skin obtained from forensic autopsy samples, accurately mimics in vivo skin conditions for evaluating the effectiveness of disinfection against the virus. Using this model, we evaluated disinfection effectiveness against viruses on human skin. METHODS: Ethanol (EA), isopropanol (IPA), chlorhexidine gluconate (CHG) and benzalkonium chloride (BAC) were used as target disinfectants. First, disinfectant effectiveness against SARS-CoV-2 and influenza A virus (IAV) was evaluated in vitro. Disinfectant effectiveness against SARS-CoV-2 and IAV on human skin was then evaluated by titrating viruses present on the skin after applying each disinfectant on the skin for 5-60 seconds. RESULTS: Both, SARS-CoV-2 and IAV on human skin were completely inactivated within 5 seconds by 40%-80% EA and 70% IPA (log reduction values (LRVs) were >4). However, SARS-CoV-2 and IAV were barely inactivated by 20% EA (LRVs were <1). In vitro evaluation showed that, compared with EA and IPA, CHG and BAC were significantly inferior in terms of disinfection effectiveness. Conversely, the disinfection effectiveness of CHG and BAC against SARS-CoV-2 was higher on human skin than in vitro, and increased with increases in their concentration and reaction time (LRVs of 0.2% CHG/0.05% BAC were >2, and LRVs of 1.0% CHG/0.2% BAC were >2.5). CONCLUSIONS: Proper hand hygiene practices using alcohol-based disinfectants such as EA/IPA effectively inactivate SARS-CoV-2 and IAV on human skin.

Use of chlorhexidine to eradicate oropharyngeal SARS-CoV-2 in COVID-19 patients.

As public distribution of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is underway, prevention of coronavirus disease 2019 (COVID-19) relies on minimizing spread. In this study, chlorhexidine gluconate was investigated as a topical antimicrobial agent against SARS-CoV-2. This was a randomized, prospective cohort study using chlorhexidine as an oral rinse and posterior oropharyngeal spray in hospitalized COVID-19 patients. The primary outcome was presence or absence of laboratory-confirmed SARS-CoV-2 in the oral and oropharyngeal cavities after 4 days of chlorhexidine use and standard of care (study group) or standard of care only (control group). SARS-CoV-2 was eliminated from the oropharynx in 62.1% of patients who used chlorhexidine as an oral rinse, versus 5.5% of the control group patients. Among patients who used a combination of oral rinse and oropharyngeal spray, 86.0% eliminated oropharyngeal SARS-CoV-2, versus 6.3% of control patients. Chlorhexidine is a simple and safe addition to current COVID-19 prevention guidelines and may play a significant role in reducing disease spread.

Efficacy of commercial mouth-rinses on SARS-CoV-2 viral load in saliva: randomized control trial in Singapore.

PURPOSE: One of the key approaches to minimize the risk of COVID-19 transmission would be to reduce the titres of SARS-CoV-2 in the saliva of infected COVID-19 patients. This is particularly important in high-risk procedures like dental treatment. The present randomized control trial evaluated the efficacy of three commercial mouth-rinse viz. povidone-iodine (PI), chlorhexidine gluconate (CHX) and cetylpyridinium chloride (CPC), in reducing the salivary SARS-CoV-2 viral load in COVID-19 patients compared with water. METHODS: A total of 36 SARS-CoV-2-positive patients were recruited, of which 16 patients were randomly assigned to four groups-PI group (n = 4), CHX group (n = 6), CPC group (n = 4) and water as control group (n = 2). Saliva samples were collected from all patients at baseline and at 5 min, 3 h and 6 h post-application of mouth-rinses/water. The samples were subjected to SARS-CoV-2 RT-PCR analysis. RESULTS: Comparison of salivary Ct values of patients within each group of PI, CHX, CPC and water at 5 min, 3 h and 6 h time points did not show any significant differences. However, when the Ct value fold change of each of the mouth-rinse group patients were compared with the fold change of water group patients at the respective time points, a significant increase was observed in the CPC group patients at 5 min and 6 h and in the PI group patients at 6 h. CONCLUSION: The effect of decreasing salivary load with CPC and PI mouth-rinsing was observed to be sustained at 6 h time point. Within the limitation of the current study, as number of the samples analyzed, the use of CPC and PI formulated that commercial mouth-rinses may be useful as a pre-procedural rinse to help reduce the transmission of COVID-19. ISRCTN (ISRCTN95933274), 09/09/20, retrospectively registered.