Filtration performance, fit test and side effects of respiratory personal protective equipment following decontamination: Observations for user safety and comfort.

OBJECTIVE: While facing personal protective equipment (PPE) shortages during the COVID-19 pandemic, several institutions looked to PPE decontamination and reuse options. This study documents the effect of two hydrogen peroxide treatments on filtration efficiency and fit tests as well as the side effects for volunteers after the decontamination of N95 filtering facepiece respirators (FFRs). We also propose an efficient and large-scale treatment protocol that allows for the traceability of this protective equipment in hospitals during PPE shortages. METHODS: The effects of low-temperature hydrogen peroxide sterilization and hydrogen peroxide vapor (HPV) on two FFR models (filtration, decontamination level, residual emanation) were evaluated. Ten volunteers reported comfort issues and side effects after wearing 1h FFRs worn and decontaminated up to five times. RESULTS: The decontamination process does not negatively affect FFR efficiency, but repeated use and handling tend to lead to damage, limiting the number of times FFRs can be reused. Moreover, the recommended 24-h post-treatment aeration does not sufficiently eliminate residual hydrogen peroxide. Prolonged aeration time increased user comfort when using decontaminated FFRs. CONCLUSIONS: HPV and low-temperature hydrogen peroxide sterilization seem to be appropriate treatments for FFR decontamination when the PPE is reused by the same user. PPE decontamination and reuse methods should be carefully considered as they are critical for the comfort and safety of healthcare workers.

Impact of diet on human nutrition, immune response, gut microbiome, and cognition in an isolated and confined mission environment.

Long-duration spaceflight impacts human physiology, including well documented immune system dysregulation. The space food system has the potential to serve as a countermeasure to maladaptive physiological changes during spaceflight. However, the relationship between dietary requirements, the food system, and spaceflight adaptation requires further investigation to adequately define countermeasures and prioritize resources on future spaceflight missions. We evaluated the impact of an enhanced spaceflight diet, with increased quantity and variety of fruits, vegetables, fish, and other foods rich in flavonoids and omega-3 fatty acids, compared to a standard spaceflight diet on multiple health and performance outcomes in 16 subjects over four 45-day closed chamber missions in the NASA Human Exploration Research Analog (HERA). Subjects consuming the enhanced spaceflight diet had lower cholesterol levels, lower stress (i.e. cortisol levels), better cognitive speed, accuracy, and attention, and a more stable microbiome and metatranscriptome than subjects consuming the standard diet. Although no substantial changes were observed in the immune response, there were also no immune challenges, such as illness or infection, so the full benefits of the diet may not have been apparent in these analog missions. These results indicate that a spaceflight diet rich in fruits, vegetables, and omega-3 fatty acids produces significant health and performance benefits even over short durations. Further investigation is required to fully develop dietary countermeasures to physiological decrements observed during spaceflight. These results will have implications for food resource prioritization on spaceflight missions.

A case of primary COVID-19 pneumonia: plausible airborne transmission of SARS-CoV-2.

BACKGROUND: The different clinical manifestations, from none to severe, and the variability in efficacy of SARS-CoV-2 diagnosis by upper respiratory tract testing, make diagnosis of COVID-19 and prevention of transmission especially challenging. In addition, the ways by which the virus can most efficiently transmit still remain unclear. CASE PRESENTATION: We report the case a 48-year-old man who presents primary COVID-19 pneumonia. He was initially admitted for cholecystitis but, upon review of his abdominal CT scan, a segmental zone of ground glass opacity was identified in the right lower lobe. A bronchoalveolar lavage proved positive to SARS-CoV-2 by RT-qPCR, even if he tested negative by oro-nasopharyngeal swab at admission and the day after he underwent bronchoscopy. The near absence of the virus in his saliva 2 days after, combined with a very sharp increase in salivary viral load on the third day, also rule out the possibility of prior viral replication in the upper airway and clearance. In addition, rapidly increasing bilateral alveolar lung infiltrates appeared as the upper respiratory tests begin to detect the virus. CONCLUSIONS: For this patient to have developed primary COVID-19 pneumonia, a contagious aerosol must have traveled to the lower respiratory system. This case gives indirect but compelling evidence that aerosol may spread the virus. It also highlights the limitations of oral and nasal testing methods and the importance of anatomical considerations when studying infections by SARS-CoV-2.

Non-small cell lung cancer microbiota characterization: Prevalence of enteric and potentially pathogenic bacteria in cancer tissues.

Following recent findings linking the human gut microbiota to gastrointestinal cancer and its treatment, the plausible relationship between lung microbiota and pulmonary cancer is explored. This study aims at characterizing the intratumoral and adjacent healthy tissue microbiota by applying a 16S rRNA gene amplicon sequencing protocol to tissue samples of 29 non-small cancer patients. Emphasis was put on contaminant management and a comprehensive comparison of bacterial composition between cancerous and healthy adjacent tissues of lung adenocarcinoma and squamous cell carcinoma is provided. A variable degree of similarity between the two tissues of a same patient was observed. Each patient seems to possess its own bacterial signature. The two types of cancer tissue do not have a distinct bacterial profile that is shared by every patient. In addition, enteric, potentially pathogenic and pro-inflammatory bacteria were more frequently found in cancer than healthy tissue. This work brings insights into the dynamic of bacterial communities in lung cancer and provides prospective data for more targeted studies.

Development of a robust protocol for the characterization of the pulmonary microbiota.

The lack of methodological standardization diminishes the validity of results obtained and the conclusions drawn when studying the lung microbiota. We report the validation of a complete 16S rRNA gene amplicon sequencing workflow, from patient recruitment to bioinformatics, tailored to the constrains of the pulmonary environment. We minimize the impact of contaminants and establish negative controls to track and account for them at every step. Enzymatic and mechanical homogenization combined to commercially available extraction kits allow for a fast and reliable extraction of bacterial DNA. The DNA extraction kits have a significant impact on the bacterial composition of the controls. The bacterial signatures of extracted cancerous and healthy human tissues from 5 patients are highly distinguishable from methodological controls. Our work expands our understanding of low microbial burdened environments analysis. This article is to be a starting point towards methodological standardization and the implementation of proper sampling procedures in the study of lung microbiota.

Positive no-touch surfaces and undetectable SARS-CoV-2 aerosols in long-term care facilities: An attempt to understand the contributing factors and the importance of timing in air sampling campaigns.

BACKGROUND: Long-term care facilities (LTCF) are environments particularly favorable to coronavirus disease (SARS-CoV-2) pandemic outbreaks, due to the at-risk population they welcome and the close proximity of residents. Yet, the transmission dynamics of the disease in these establishments remain unclear. METHODS: Air and no-touch surfaces of 31 rooms from 7 LTCFs were sampled and SARS-CoV-2 was quantified by real-time reverse transcription polymerase chain reaction (RT-qPCR). RESULTS: Air samples were negative but viral genomes were recovered from 20 of 62 surface samples at concentrations ranging from 13 to 36,612 genomes/surface. Virus isolation (culture) from surface samples (n = 7) was negative. CONCLUSIONS: The presence of viral RNA on no-touch surfaces is evidence of viral dissemination through air, but the lack of airborne viral particles in air samples suggests that they were not aerosolized in a significant manner during air sampling sessions. The air samples were collected 8 to 30 days after the residents' symptom onset, which could indicate that viruses are aerosolized early in the infection process. Additional research is needed to evaluate viral viability conservation and the potential role of direct contact and aerosols in SARS-CoV-2 transmission in these institutions.

Low incidence of airborne SARS-CoV-2 in acute care hospital rooms with optimized ventilation.

The worldwide repercussions of COVID-19 sparked important research efforts, yet the detailed contribution of aerosols in the transmission of SARS-CoV-2 has not been elucidated. In an attempt to quantify viral aerosols in the environment of infected patients, we collected 100 air samples in acute care hospital rooms hosting 22 patients over the course of nearly two months using three different air sampling protocols. Quantification by RT-qPCR (ORF1b) led to 11 positive samples from 6 patient rooms (Ct < 40). Viral cultures were negative. No correlation was observed between particular symptoms, length of hospital stay, clinical parameters, and time since symptom onset and the detection of airborne viral RNA. Low detection rates in the hospital rooms may be attributable to the appropriate application of mitigation methods according to the risk control hierarchy, such as increased ventilation to 4.85 air changes per hour to create negative pressure rooms. Our work estimates the mean emission rate of patients and potential airborne concentration in the absence of ventilation. Additional research is needed understand aerosolization events occur, contributing factors, and how best to prevent them.

An Overview of Bioinformatics Tools for DNA Meta-Barcoding Analysis of Microbial Communities of Bioaerosols: Digest for Microbiologists.

High-throughput DNA sequencing (HTS) has changed our understanding of the microbial composition present in a wide range of environments. Applying HTS methods to air samples from different environments allows the identification and quantification (relative abundance) of the microorganisms present and gives a better understanding of human exposure to indoor and outdoor bioaerosols. To make full use of the avalanche of information made available by these sequences, repeated measurements must be taken, community composition described, error estimates made, correlations of microbiota with covariates (variables) must be examined, and increasingly sophisticated statistical tests must be conducted, all by using bioinformatics tools. Knowing which analysis to conduct and which tools to apply remains confusing for bioaerosol scientists, as a litany of tools and data resources are now available for characterizing microbial communities. The goal of this review paper is to offer a guided tour through the bioinformatics tools that are useful in studying the microbial ecology of bioaerosols. This work explains microbial ecology features like alpha and beta diversity, multivariate analyses, differential abundances, taxonomic analyses, visualization tools and statistical tests using bioinformatics tools for bioaerosol scientists new to the field. It illustrates and promotes the use of selected bioinformatic tools in the study of bioaerosols and serves as a good source for learning the "dos and don'ts" involved in conducting a precise microbial ecology study.

Ozone efficacy for the control of airborne viruses: Bacteriophage and norovirus models.

This study was designed to test the efficacy of an air treatment using ozone and relative humidity (RH) for the inactivation of airborne viruses. Four phages (φX174, PR772, MS2 and φ6) and one eukaryotic virus (murine norovirus MNV-1) were exposed to low ozone concentrations (1.23 ppm for phages and 0.23 ppm for MNV-1) and various levels of RH for 10 to 70 minutes. The inactivation of these viruses was then assessed to determine which of the tested conditions provided the greatest reduction in virus infectivity. An inactivation of at least two orders of magnitude for φX174, MS2 and MNV-1 was achieved with an ozone exposure of 40 minutes at 85% RH. For PR772 and φ6, exposure to the reference condition at 20% RH for 10 minutes yielded the same results. These findings suggest that ozone used at a low concentration is a powerful disinfectant for airborne viruses when combined with a high RH. Air treatment could therefore be implemented inside hospital rooms ventilated naturally.