Airborne antibiotic resistome and human health risk in railway stations during COVID-19 pandemic.

Antimicrobial resistance is recognized as one of the greatest public health concerns. It is becoming an increasingly threat during the COVID-19 pandemic due to increasing usage of antimicrobials, such as antibiotics and disinfectants, in healthcare facilities or public spaces. To explore the characteristics of airborne antibiotic resistome in public transport systems, we assessed distribution and health risks of airborne antibiotic resistome and microbiome in railway stations before and after the pandemic outbreak by culture-independent and culture-dependent metagenomic analysis. Results showed that the diversity of airborne antibiotic resistance genes (ARGs) decreased following the pandemic, while the relative abundance of core ARGs increased. A total of 159 horizontally acquired ARGs, predominantly confering resistance to macrolides and aminoglycosides, were identified in the airborne bacteria and dust samples. Meanwhile, the abundance of horizontally acquired ARGs hosted by pathogens increased during the pandemic. A bloom of clinically important antibiotic (tigecycline and meropenem) resistant bacteria was found following the pandemic outbreak. 251 high-quality metagenome-assembled genomes (MAGs) were recovered from 27 metagenomes, and 86 genera and 125 species were classified. Relative abundance of ARG-carrying MAGs, taxonomically assigned to genus of Bacillus, Pseudomonas, Acinetobacter, and Staphylococcus, was found increased during the pandemic. Bayesian source tracking estimated that human skin and anthropogenic activities were presumptive resistome sources for the public transit air. Moreover, risk assessment based on resistome and microbiome data revealed elevated airborne health risks during the pandemic.

What can cerebrospinal fluid testing and brain autopsies tell us about viral neuroinvasion of SARS-CoV-2.

To provide instructive clues for clinical practice and further research of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we analyzed the existing literature on viral neuroinvasion of SARS-CoV-2 in coronavirus disease 2019 (COVID-19) patients. To date, SARS-CoV-2 has been detected in the cerebrospinal fluid (CSF) or brain parenchyma in quite a few patients, which provide undeniable evidence for the neuroinvasive potential of this novel coronavirus. In contrast with the cerebrum and cerebellum, the detection rate of SARS-CoV-2 was higher in the olfactory system and the brainstem, both of which also showed severe microgliosis and lymphocytic infiltrations. As compared with the number of patients who underwent viral testing in the central nervous system (CNS), the number of patients showing positive results seems very small. However, it seems too early to conclude that the neuroinvasion of SARS-CoV-2 is rare in COVID-19 patients because the detection methods or sampling procedures in some studies may not be suitable or sufficient to reveal the CNS infection induced by neurotropic viruses. Moreover, the primary symptoms and/or causes of death were distinctly different among examined patients, which probably caused more conspicuous pathological changes than those due to the direct infection that usually localized to specific brain areas. Unfortunately, most autopsy studies did not provide sufficient details about neurological symptoms or suspected diagnoses of the examined patients, and the documentation of neuropathological changes was often incomplete. Given the complex pathophysiology of COVID-19 and the characteristics of neurotropic viruses, it is understandable that any study of the CNS infection may inevitably have limitations.

Evidence of central nervous system infection and neuroinvasive routes, as well as neurological involvement, in the lethality of SARS-CoV-2 infection.

The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become a significant and urgent threat to global health. This review provided strong support for central nervous system (CNS) infection with SARS-CoV-2 and shed light on the neurological mechanism underlying the lethality of SARS-CoV-2 infection. Among the published data, only 1.28% COVID-19 patients who underwent cerebrospinal fluid (CSF) tests were positive for SARS-CoV-2 in CSF. However, this does not mean the absence of CNS infection in most COVID-19 patients because postmortem studies revealed that some patients with CNS infection showed negative results in CSF tests for SARS-CoV-2. Among 20 neuropathological studies reported so far, SARS-CoV-2 was detected in the brain of 58 cases in nine studies, and three studies have provided sufficient details on the CNS infection in COVID-19 patients. Almost all in vitro and in vivo experiments support the neuroinvasive potential of SARS-CoV-2. In infected animals, SARS-CoV-2 was found within neurons in different brain areas with a wide spectrum of neuropathology, consistent with the reported clinical symptoms in COVID-19 patients. Several lines of evidence indicate that SARS-CoV-2 used the hematopoietic route to enter the CNS. But more evidence supports the trans-neuronal hypothesis. SARS-CoV-2 has been found to invade the brain via the olfactory, gustatory, and trigeminal pathways, especially at the early stage of infection. Severe COVID-19 patients with neurological deficits are at a higher risk of mortality, and only the infected animals showing neurological symptoms became dead, suggesting that neurological involvement may be one cause of death.

Neurological involvement in the respiratory manifestations of COVID-19 patients.

The peculiar features of coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), are challenging the current biological knowledge. Early in Feb, 2020, we suggested that SARS-CoV-2 may possess neuroinvasive potential similar to that of many other coronaviruses. Since then, a variety of neurological manifestations have been associated with SARS-CoV-2 infection, which was supported in some patients with neuroimaging and/or cerebrospinal fluid tests. To date, at least 27 autopsy studies on the brains of COVID-19 patients can be retrieved through PubMed/MEDLINE, among which neuropathological alterations were observed in the brainstem in 78 of 134 examined patients, and SARS-CoV-2 nucleic acid and viral proteins were detected in the brainstem in 16/49 (32.7%) and 18/71 (25.3%) cases, respectively. To shed some light on the peculiar respiratory manifestations of COVID-19 patients, this review assessed the existing evidence about the neurogenic mechanism underlying the respiratory failure induced by SARS-CoV-2 infection. Acknowledging the neurological involvement has important guiding significance for the prevention, treatment, and prognosis of SARS-CoV-2 infection.

The possible impairment of respiratory-related neural loops may be associated with the silent pneumonia induced by SARS-CoV-2.

As compared to many other viral pulmonary infections, there existed several peculiar manifestations in the COVID-19 patients, including the "silence" of pneumonia in both mild and severe cases and a long intensive care unit stay for those requiring invasive mechanical ventilation. Similar silent pneumonia has been documented in the infectioninduced by H5N1 influenza virus HK483 and was found to result from the direct attack of the virus on the bronchopulmonary C-fibers at the early stage and the final infection in the brainstem at the late stage. The long stay of critical patients in the intensive care unit is possibly due to the depression of central respiratory drive, which resulted in the failure to wean from the mechanic ventilation. Carotid and aortic bodies and bronchopulmonary C-fibers are two key peripheral components responsible for the chemosensitive responses in the respiratory system, while triggering respiratory reflexes depends predominantly on the putative chemosensitive neurons located in the pontomedullary nuclei. In view of the findings for the H5N1 influenza virus, the silence of pneumonia induced by SARS-CoV-2 may be due to the possible impairment of peripheral chemosensitive reflexes as well as the damage to the respiratory-related central neurons.