Is ultraviolet light disinfection fit to be the future standard for the disinfection of flexible endoscopes without a working channel?

OBJECTIVE

To investigate colony-forming unit (CFU) reduction on contaminated flexible endoscopes (FEs) without a working channel after UV-C light disinfection, compared to the current disinfection method with the endoscope washer disinfector (EWD).

DESIGN, SETTING AND PARTICIPANTS

After pharyngolaryngoscopy, a manual pre-cleaning with tap water was performed. A culture was then collected by rolling the distal 8-10 cm of the FE over an Agar plate. The FE was disinfected using the D60 (60-s disinfection process with UV-C light) or the EWD (gold standard reprocessing process with water and chemicals). Another culture was then taken. After incubation, a CFU count was performed.

RESULTS

A total of 200 FEs without a working channel were divided equally between the two disinfection groups. After clinical use and manual pre-cleaning, 84 of the 100 (84.0%) (UV-C light group) and 79 of the 100 (79.0%) (EWD) FEs were contaminated with at least 1 CFU. FEs that showed no contamination after use were excluded from further analysis. After disinfection with UV-C light, 72 (85.7%) FEs showed no contamination (i.e., 0 CFUs) versus 66 (83.5%) FEs after reprocessing with the EWD.

CONCLUSION

There is no difference in CFUs reduction on contaminated FEs without a working channel between UV-C light disinfection and the current gold standard, the EWD.

Microbial diversity formation and maintenance due to temporal niche differentiation caused by low-dose ionizing radiation in oligotrophic environments

The planetary protection strives to minimize the contamination of microorganisms in spacecrafts. However, it is reported that microbial diversity is abnormally high in the International Space Station (ISS) after long-term exposure to low-dose ionizing radiation (LDIR). It remains a mystery why LDIR leads to the formation and maintenance of high microbial diversity in oligotrophic environments like the ISS. In this study, an artificial microbial community has been cultivated without and with LDIR, respectively. The microbial community was composed of three common microbial species, i.e., Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa in the ISS. After analyzing the differences in microbial physiological and behavioral response characteristics in the two scenarios, a reasonable hypothesis was proposed to elucidate the formation and maintenance mechanisms of high microbial diversity in oligotrophic environments with the LDIR. Then a set of kinetic models with time-lag were developed based on this hypothesis, observed phenomena, and experimental data. Finally, these kinetic models were sufficiently validated, and the hypothesis was fully confirmed through large-scale digital simulations. Briefly, as a decisive succession mechanism in oligotrophic environments with LDIR, temporal niche differentiation (TND) caused by microbial delayed responses to LDIR can give rise to asynchronously convergent fluctuations of microbial populations and significantly alleviate the intra- and interspecific competitions. Such a mechanism can drive the microbial communities in oligotrophic environments with LDIR to form and maintain high species diversity.

Inactivation methods for whole influenza vaccine production

Despite tremendous efforts toward vaccination, influenza remains an ongoing global threat. The induction of strain-specific neutralizing antibody responses is a common phenomenon during vaccination with the current inactivated influenza vaccines, so the protective effect of these vaccines is mostly strain-specific. There is an essential need for the development of next-generation vaccines, with a broad range of immunogenicity against antigenically drifted or shifted influenza viruses. Here, we evaluate the potential of whole inactivated vaccines, based on chemical and physical methods, as well as new approaches to generate cross-protective immune responses. We also consider the mechanisms by which some of these vaccines may induce CD8⁺ T-cells cross-reactivity with different strains of influenza. In this review, we have focused on conventional and novel methods for production of whole inactivated influenza vaccine. As well as chemical modification, using formaldehyde or β-propiolactone and physical manipulation by ultraviolet radiation or gamma-irradiation, novel approaches, including visible ultrashort pulsed laser, and low-energy electron irradiation are discussed. These two latter methods are considered to be attractive approaches to design more sophisticated vaccines, due to their ability to maintain most of the viral antigenic properties during inactivation and potential to produce cross-protective immunity. However, further studies are needed to validate them before they can replace traditional methods for vaccine manufacturing.