Pulsed xenon ultraviolet and non-thermal atmospheric plasma treatments are effective for the disinfection of air in hospital blood sampling rooms

Nonthermal plasma air disinfection for the inactivation of airborne microorganisms in an experimental chamber and indoor air

AIMS

Airborne transmission of diseases presents a serious threat to human health, so effective air disinfection technology to eliminate microorganisms in indoor air is very important. This study evaluated the effectiveness of a non-thermal plasma (NTP) air disinfector in both laboratory experiments and real environments.

METHODS AND RESULTS

An experimental chamber was artificially polluted with a bioaerosol containing bacteria or viruses. Additionally, classroom environments with and without people present were used in field tests. Airborne microbial and particle concentrations were quantified. A 3.0 log10 reduction in the initial load was achieved when a virus-containing aerosol was disinfected for 60 min and a bacteria-containing aerosol was disinfected for 90 min. In the field test, when no people were present in the room, NTP disinfection decreased the airborne microbial and particle concentrations (P < 0.05). When people were present in the room, their constant activity continuously contaminated the indoor air, but all airborne indicators decreased (P < 0.05) except for planktonic bacteria (P = 0.094).

CONCLUSIONS

NTP effectively inactivated microorganisms and particles in indoor air.

Application Effect of the 6S Care Model in Sterilization in the Department of Stomatology and Its Impact on the Incidence of Nosocomial Infection

Objective

The study aimed to explore the effectiveness of the 6S care model in sterilization in department of stomatology and its impact on the incidence of nosocomial infections.

Methods

The infection surveillance indicators of the department of stomatology implementing the routine sterilization care model in 2019 were selected as the general group (including 140 patients and 140 cases of oral instrument kits for unpacking), and the infection surveillance indicators of the department of stomatology implementing the 6S care model in 2020 were selected as the 6S group (including 140 patients and 140 cases of oral instrument kits for unpacking). Analysis of the air culture qualification rate of the consultation room + operating room, medical equipment sterilization qualification rate, medical equipment damage rate, incidence of nosocomial infections, satisfaction of medical and nursing staff with instrument sterilization, and patient satisfaction with medical and nursing staff care services under different care models was carried out.

Result

The air culture pass rate of the consultation room + operating room in the 6S group was 96.43% (135/140), which was higher than 90.00% (126/140) in the general group, and the difference between the two groups was statistically significant (P > 0.05). The sterilization pass rate of medical devices in the 6S group was 100% (140/140), which was higher than 95.71% (134/140) in the general group, and the difference between the two groups was statistically significant (P > 0.05). The medical device damage rate in the 6S group was 0.71% (1/140), which was lower than 7.14% (10/140) in the general group, and the difference between the two groups was statistically significant (P > 0.05). The incidence of nosocomial infection in the 6S group was 0.71% (1/140), lower than 5.71% (8/140) in the general group, and the difference between the two groups was statistically significant (P > 0.05). In the 6S care model, the satisfaction score of 38 healthcare workers with the disinfection of instruments was (96.55 ± 2.40), which was higher than that of the general group (87.79 ± 3.14), and the difference between the two groups was statistically significant (P > 0.05). The total nursing satisfaction of the 6S group was 97.86% (137/140), which was higher than 91.43% (128/140) of the general group, and the difference between the two groups was statistically significant (P > 0.05).

Conclusion

The application of the 6S care model in the sterilization of the department of stomatology can significantly improve the passing rate of infection monitoring indicators in the department of stomatology, reduce the occurrence of medical device damage and nosocomial infection, and have high satisfaction among doctors and patients, which has the value of promotion.

A Practical Assessment of the Disinfectant Efficacy of UV Light with and without Ozone Using a Novel Transfer Hatch in a Research Animal Facility

Most in vivo animal research and breeding using mice and rats in China takes place in facilities under barrier conditions. Items being moved across the barrier are typically disinfected using UV radiation in a transfer hatch. However, the time periods necessary for this disinfection technique are inefficient, and disinfection is frequently incomplete, especially if concealed surfaces are present. The current study used a newly developed transfer hatch incorporating both UV and ozone disinfection to examine disinfection efficacy against 4 bacteria species (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii). Disinfection trials used UV and ozone, applied separately and in combination, for up to 30 min. Separate and combined treatments were also tested with a UV barrier. We found that if UV radiation has direct contact with surfaces, it is an efficient disinfection method. However, where surfaces are concealed by a UV barrier, UV radiation performs relatively poorly. The results of this study indicate that a combination of UV and ozone produces the most effective disinfection and is markedly quicker than current disinfection times for UV applied on its own. This novel transfer hatch design therefore allows more complete and efficient disinfection, improves workflow, and reduces barrier breaches by pathogens that may affect animal health and welfare and compromise research outcomes.

Air filtration as a tool for the reduction of viral aerosols

For testing the effectiveness of air purification devices in regard to the reduction of virus-containing aerosols, a test method involving test viruses has been lacking until now. The use of bacteriophages (phiX174 phages) is a method to test the efficiency of air purification devices under experimental conditions. Using air purifiers with a HEPA filter H14, a 4.6-6.1 Log reduction of test viruses can be achieved if bacteriophages are directly aerosolised into the air purifier, which corresponds to a reduction of 99.9974-99.9999%. Due to the complexity and individuality of air flow, an experimental approach was used in which all outside influences were minimised. The experimental setup was practical and chosen to project a scenario of direct transmission by an emitting source to a recipient. The experiments were performed with and without the air purifier at a distance of 0.75 m and 1.5 m each. Using the air purifier at a setting of 1000 m³/h, the concentration of the phiX174 phages in the air could be reduced by 2.86 Log (mean value). Nevertheless, the experiments without the air purifier showed a similar reduction rate of 2.61 Log (mean value) after 35 min. The concentration of phiX174 phages in the air could be additionally reduced up to 1 log step (maximum value) by the use of the air purifier in comparison to the experiments without. Distance was shown to be an important factor for risk reduction.

Portable pulsed xenon ultraviolet light disinfection in a teaching hospital animal laboratory in China

An animal laboratory in a teaching hospital is a possible cause of cross infection. We aimed to assess the infection control in our animal laboratory and evaluate the disinfectant effects of a portable pulsed xenon ultraviolet (PX-UV) machine. Samples were taken from the surface of research tables, other high touch places, such as doorknobs, weighing scales, and handles of trolleys, and from air in the barrier system pre- and post-manual cleaning and post-PX-UV disinfection. The bacteria types were identified. We found that routine manual cleaning significantly reduced bacterial colony form unit (CFU)/cm² (P = .02), and the median of CFU/cm² reduced from 0.5 pre-cleaning to zero post-cleaning. PX-UV disinfection also significantly reduced residual bacterial counts (P = .002), with the highest counts 10 pre-PX-UV disinfection and 1 afterwards. Without manual cleaning, PX-UV disinfected surfaces significantly (P < .001), median count 6 pre-PX-UV disinfection and zero afterwards. PX-UV significantly reduced bacterial colony counts in the air with the median count falling from 6 to zero (P < .001). Some of the 21 species of pathogens we identified in the current study are pathogenic, resistant to antibiotics, and able to cause nosocomial infections and zoonosis. PX-UV reduced counts of most of the pathogens. PX-UV is an effective agent against these pathogens.

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An animal laboratory in a teaching hospital is a possible cause of cross infection.

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The disinfectant effect of manual cleaning and portable pulsed xenon ultraviolet (PX-UV) was compared in our laboratory.

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Manual cleaning significantly reduced bacterial counts on surfaces and PX-UV significantly reduced residual bacterial counts.

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PX-UV, without manual cleaning, significantly reduced bacterial counts on surfaces.

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PX-UV significantly reduced bacterial counts in the room air.