Efficacy of radiant catalytic ionization to reduce bacterial populations in air and on different surfaces

Confirmation of radiant catalytic ionization efficacy for airborne SARS-CoV-2 elimination indoors using "COVID19 traps"

Radiant catalytic ionization (RCI) is a novel technology that uses the appropriate wavelength (240-260 nm) and the phenomenon of photo-oxidation leading to permanent removal of viruses, bacteria, and fungi. Here, two analyses were performed. The first of them was a complete analysis of environmental biosecurity in a hospital environment. The second one was a longitudinal study with 40 patients with confirmed COVID19 and high viral load to assess the efficacy of RCI technology eliminating airborne SARS-CoV-2 indoors. A significant decrease in the number of bacteria and fungi colony-forming units (CFUs) was found in rooms with RCI when compared with rooms without it (p=0.03 for both of them). In the second part of the study, 16 samples out of 40 (40%) were positives when RCI technology was absent; whereas, these samples were negative when the equipment was on. Incidence rates (IR) with their Poisson 95% Confidence Intervals (CI) were calculated as the number of positive tests with the purifier or without it, showing an IR difference of 48.5% [CI(15.9-81), p=0.004]. Furthermore, the IR ratio was calculated obtaining a value of 3.3, confirming that RCI diminished more than 3-fold the presence of the SARS-CoV-2 in the air of the patients' rooms, thus laying the first stone in the fight for prevention of SARS-CoV-2 dissemination indoors.

Effect of Radiant Catalytic Ionization and Ozonation on Salmonella spp. on Eggshells

Three Salmonella enterica strains were used in the study (serovars: S. enteritidis, S. typhimurim and S. virchow). This study evaluated the efficacy of radiant catalytic ionization (RCI) and ozonation against Salmonella spp. on eggshell (expressed as log CFU/egg). The egg surface was contaminated three different bacterial suspension (10³ CFU/mL, 10⁵ CFU/mL and 10⁸ CFU/mL) with or without poultry manure. Experiments were conducted at 4 °C and 20 °C in three different time period: 30 min, 60 min and 120 min. Treatment with RCI reduced Salmonella numbers from 0.26 log CFU/egg in bacterial suspension 10⁸ CFU/mL, 4 °C and 20 °C, with manure for 30 min to level decrease in bacteria number below the detection limit (BDL) in bacterial suspension 10⁵ CFU/mL, 20 °C, with or without manure for 120 min. The populations of Salmonella spp. on eggs treated by ozonizer ranged from 0.20 log CFU/egg in bacteria suspension 10⁸ CFU/mL, 20 °C, with manure for 30 min to 2.73 log CFU/egg in bacterial suspension 10⁵ CFU/mL, 20 °C, with manure for 120 min. In all treatment conditions contamination with poultry manure decrease effectiveness the RCI and ozonation. In summary, RCI technology shows similar effectiveness to the ozonation, but it is safer for poultry plant workers and consumers.

Effect of radiant catalytic ionization on environmental conditions in rodent rooms and the haematological status of mice

High stocking densities, closed animal houses, and elevated concentrations of bacteria, fungi, and the products of their activity, including ammonia and hydrogen sulphide, have adverse health effects. Active techniques used to reduce unfavourable environmental conditions, such as ventilation, sprinkling, bedding sorbents, and nutritional treatments, are not always sufficient to improve the animals’ living environment. The current paper aims to evaluate the effect of radiant catalytic ionization (RCI) on airborne microorganisms, cage microbiological status, gaseous ammonia concentrations, and the haematological status of mice in animal houses. After one week of operation of an RCI system, the number of airborne bacteria and fungi in the experimental room decreased in comparison to the first day of the experiment (p < 0.05 and p < 0.05 respectively), as did the concentrations of ammonia (p < 0.01) and dust. At the same time, the basic health parameters of the mice, determined in the blood, were very similar between the control and experimental room. RCI seems to be an ideal solution to ensure high hygiene standards in animal rooms and houses with limited use of disinfectants or antibiotic treatment of sick animals. An additional, environmental benefit is the limited amount of nitrogen released.

Antimicrobial effect of radiant catalytic ionization

The main purpose of micro-organisms elimination from the air and surfaces is to ensure microbiological safety in health care facilities or food production plants. Currently, many disinfection methods are used, both physical, chemical and, increasingly, biological. Scientists seek new solutions with high antimicrobial effectiveness (especially against the drug-resistant strains of bacteria), low production and operating costs, and, above all, the safety of patients and food consumers. The limitation of the methods used so far is primarily the micro-organisms acquire the resistance, mainly to antimicrobial agents. One of the new and alternative methods of disinfection is radiant catalytic ionization (RCI). RCI is an active method of air and surface purification. The technology proved high efficiency against viruses, Gram-positive and -negative bacteria, and fungi, both in the air and on surfaces (planktonic forms and biofilm). RCI has many advantages as well as some minor limitations. This overview summarizes the current knowledge about RCI technology.

Emerging Technologies for Aerial Decontamination of Food Storage Environments to Eliminate Microbial Cross-Contamination

Air is recognized as an important source of microbial contamination in food production facilities and has the potential to contaminate the food product causing food safety and spoilage issues for the food industry. Potential for aerial microbial contamination of food can be a particular issue during storage in cold rooms when the food is not packaged and is exposed to contaminated air over a prolonged period. Thus, there are potential benefits for the food industry for an aerial decontamination in cold storage facilities. In this paper, aerial decontamination approaches are reviewed and challenges encountered for their applications are discussed. It is considered that current systems may not be completely effective and environmentally friendly, therefore, it is of great significance to consider the development of nonresidual and verified decontamination technologies for the food industry and, in particular, for the cold storage rooms.

The Antimicrobial Effect of Radiant Catalytic Ionization on the Bacterial Attachment and Biofilm Formation by Selected Foodborne Pathogens under Refrigeration Conditions

The decontamination of food contact surfaces is a major problem for the food industry. The radiant catalytic ionization (RCI) method, based on the ionization process, may be an alternative for conventional decontamination procedures. The advantage of this technique is the possibility of its application to household refrigerating appliances and industrial cold rooms. This study aimed to assess the effect of RCI on the reduction of Campylobacter jejuni, Listeria monocytogenes, and Salmonella Enteritidis from the biofilms formed on a glass surface under refrigeration conditions. Bacterial biofilms were exposed to RCI for 24 h and after 12 (variant I) and 72 h (variant II) of the glass surface contamination. In the last variant (III), the contaminated meat was placed on the glass surface in the refrigerator and subjected to RCI treatment for 72 h. The significantly highest values of absolute reduction efficiency coefficient E were found for the bacterial attachment stage of biofilm formation (variant I). The research proves the efficiency of the RCI method in the reduction of bacteria number from a glass surface.

Effect of Selected Environmental Factors on the Microbicidal Effectiveness of Radiant Catalytic Ionization

The aim of this study was the assessment of the effect of time exposure, temperature, distance, and organic contaminants on radiant catalytic ionization (RCI) microbicidal effectiveness. The number of all examined bacteria decreased together with time exposure of RCI. The lowest recovery was obtained, both from the rubber surface (6.36 log CFU × cm-2) and steel (6.04 log CFU × cm-2) in the case of Escherichia coli O157:H7. On the other hand, Staphylococcus aureus was isolated in the largest number (rubber: 7.88 log CFU × cm-2, steel: 7.79 log CFU × cm-2). Among the tested environmental conditions, the greatest bacterial population was re-isolated at 4°C (distance: 0.5 m, time: 24 h), whereas the lowest population was found at a distance of 0.5 m (temperature: 20°C, time: 24 h) and on surfaces without contamination. In the samples treated with RCI, the bacterial population was the lowest on non-contaminated surfaces, ranging from 3.76 log CFU × cm-2 (E. coli O157:H7) to 5.58 log CFU × cm-2 (S. aureus) for the rubber, and from 3.26 log CFU × cm-2 (E. coli O157:H7) to 5.20 log CFU × cm-2 (S. aureus) for the stainless steel. The highest bacteria number was isolated from surfaces contaminated with meat and fish pulp. The lowest bacterial reduction caused by RCI was found in the case of rubber contaminated with meat-fish pulp (24 h, 0.5 m, 20°C). The reduction rate was equal to 0.89 log CFU × cm-2 for S. aureus, 1.17 log CFU × cm-2 for Listeria monocytogenes, 1.43 log CFU × cm-2 for Salmonella Enteritidis and 1.61 log CFU × cm-2 for E. coli O157:H7. In turn, the greatest bacterial reduction was found in the case of non-contaminated steel (24 h, 0.5 m, 37°C). The reduction rate was equal to 4.52 log CFU × cm-2 for L. monocytogenes, 3.61 log CFU × cm-2 for S. Enteritidis, 2.98 log CFU × cm-2 for E. coli O157:H7 and 2.77 log CFU × cm-2 for S. aureus. RCI allows the inactivation of pathogens from stainless steel and rubber surfaces. Its efficacy is species-dependent and affected by environmental factors.

Analysis of the results of empirical research and surveys of perceived indoor temperature depending on gender and seasons

The indoor thermal condition tests were conducted as real and declared by the respondents. The tests were carried out in the laboratory room in Bialystok. The object is a detached, two-storey building with a cellar. The tests were carried out from February to May 2015. In 1 week, on average, ten measurement series were carried out. During one experiment series, there were between 10 and 15 students present in the room. The aim of the publication is to analyze the results of declared perceived temperature tests in the room depending on the gender, the season and indoor and outdoor temperature conditions. On the basis of statistical analysis of the test results, it was found that in the analyzed age group, the perceived temperature declared in the room is not affected by the respondent's gender. The conclusion is that the temperature sensations of young (and probably healthy) people who do not do physical work are similar, regardless of gender. Differences between the average perceived temperature in the room, declared by all respondents in winter and declared in spring are statistically significant. The indoor perceived temperature declared in the winter is almost constant and does not depend on the temperature of the perceived temperature of outdoor air.

The effectiveness of radiant catalytic ionization in inactivation of Listeria monocytogenes planktonic and biofilm cells from food and food contact surfaces as a method of food preservation

AIMS

The aim of the study was to evaluate the microbicidal effectiveness of radiant catalytic ionization (RCI) against Listeria monocytogenes strains in the form of planktonic cells and biofilm on food products and food contact surfaces as a method of food preservation.

METHODS AND RESULTS

The study material comprised six strains of L. monocytogenes, isolated from food. Samples of different types of food available by retail (raw carrot, frozen salmon filets, soft cheese) and the fragments of surfaces (stainless steel AISI 304, rubber, milled rock tiles, polypropylene) were used in the experiment. The obtained results showed the effectiveness of RCI in the inactivation of both forms of the tested L. monocytogenes strains on all the surfaces. The effectiveness of RCI for biofilm forms was lower as compared with planktonic forms. The PRR value ranged from 18·19 to 99·97% for planktonic form and from 3·92 to 70·10% for biofilm.

CONCLUSIONS

The RCI phenomenon induces the inactivation of L. monocytogenes on surfaces of food and materials used in the processing industry to a varying degree, depending on the manner of surface contamination, the properties of the contaminated materials as well as on the origin of the strain and the properties of surrounding dispersive environment in which the micro-organisms were suspended.

SIGNIFICANCE AND IMPACT OF THE STUDY

Searching of new actions aimed at the reduction of the microbial contamination of food and food contact surfaces are extremely important. RCI method has been already described as an effective technique of microbial and abiotic pollution removal from air. However, our studies provide new, additional data related to evaluation the RCI efficacy against microbes on different surfaces, both in planktonic and biofilm form.