ABSTRACT
Disinfection plays an essential role in waterborne pathogen control and disease prevention, especially during the COVID-19 pandemic. Catalyst-free solar light/periodate (PI) system has recently presented great potential in water disinfection, whereas the in-depth chemical and microbiological mechanisms for efficient bacterial inactivation remain unclear. Our work delineated firstly the critical role of singlet oxygen, instead of reported hydroxyl radicals and superoxide radicals, in dominating bacterial inactivation by the PI/simulated sunlight (SSL) system. Multi-evidence demonstrated the prominent disinfection performance of this system for Staphylococcus aureus in terms of culturability (> 6 logs CFU), cellular integrity, and metabolic activity. Particularly, the excellent intracellular DNA removal (> 95%) indicated that PI/SSL system may function as a selective disinfection strategy to diminish bacterial culturability without damaging the cell membrane. The PI/SSL system could also effectively inhibit bacterial regrowth for > 5 days and horizontal gene transfer between E. coli genera. Nontargeted metabolomic analysis suggested that PI/SSL system inactivated bacteria by triggering the accumulation of intracellular reactive oxygen species and the depletion of reduced glutathione. Additionally, the PI/SSL system could accomplish simultaneous micropollutant removal and bacterial inactivation, suggesting its versatility in water decontamination. Overall, this study deciphers more comprehensive antibacterial mechanisms of this environmentally friendly disinfection system, facilitating the technical development and application of the selective disinfection strategy in environmental pathogen control. [Display omitted] • PI/SSL system selectively inactivates cells by targeting intracellular DNA first. • PI/SSL treatment inhibits bacterial regrowth and horizontal gene transfer potential. • The bactericidal effect of 1O 2 in PI/SSL system was proposed for the first time. • Metabolomics showed that ROS accumulation is one of the antibacterial mechanisms. • PI/SSL system holds great promise in decontamination of the actual water system. [ FROM AUTHOR]
ABSTRACT
Disinfection plays an essential role in waterborne pathogen control and disease prevention, especially during the COVID-19 pandemic. Catalyst-free solar light/periodate (PI) system has recently presented great potential in water disinfection, whereas the in-depth chemical and microbiological mechanisms for efficient bacterial inactivation remain unclear. Our work delineated firstly the critical role of singlet oxygen, instead of reported hydroxyl radicals and superoxide radicals, in dominating bacterial inactivation by the PI/simulated sunlight (SSL) system. Multi-evidence demonstrated the prominent disinfection performance of this system for Staphylococcus aureus in terms of culturability (> 6 logs CFU), cellular integrity, and metabolic activity. Particularly, the excellent intracellular DNA removal (> 95%) indicated that PI/SSL system may function as a selective disinfection strategy to diminish bacterial culturability without damaging the cell membrane. The PI/SSL system could also effectively inhibit bacterial regrowth for > 5 days and horizontal gene transfer between E. coli genera. Nontargeted metabolomic analysis suggested that PI/SSL system inactivated bacteria by triggering the accumulation of intracellular reactive oxygen species and the depletion of reduced glutathione. Additionally, the PI/SSL system could accomplish simultaneous micropollutant removal and bacterial inactivation, suggesting its versatility in water decontamination. Overall, this study deciphers more comprehensive antibacterial mechanisms of this environmentally friendly disinfection system, facilitating the technical development and application of the selective disinfection strategy in environmental pathogen control.
ABSTRACT
The coronavirus disease 2019 (COVID-19) triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) erupted in Hubei Province of China in December 2019 and has become a pandemic. Severe COVID-19 patients who suffer from acute respiratory distress syndrome (ARDS) and multi-organ dysfunction have high mortality. Several studies have shown that this is closely related to the cytokine release syndrome (CRS), often loosely referred to as cytokine storm. IL-6 is one of the key factors and its level is positively correlated with the severity of the disease. The molecular mechanisms for CRS in COVID-19 are related to the effects of the S-protein and N-protein of the virus and its ability to trigger NF-κB activation by disabling the inhibitory component IκB. This leads to activation of immune cells and the secretion of proinflammatory cytokines such as IL-6 and TNF-α. Other mechanisms related to IL-6 include its interaction with GM-CSF and interferon responses. The pivotal role of IL-6 makes it a target for therapeutic agents and studies on tocilizumab are already ongoing. Other possible targets of treating CRS in COVID-19 include IL-1ß and TNF-α. Recently, reports of a CRS like illness called multisystem inflammatory syndrome in children (MIS-C) in children have surfaced, with a variable presentation which in some cases resembles Kawasaki disease. It is likely that the immunological derangement and cytokine release occurring in COVID-19 cases is variable, or on a spectrum, that can potentially be governed by genetic factors. Currently, there are no approved biological modulators for the treatment of COVID-19, but the urgency of the pandemic has led to numerous clinical trials worldwide. Ultimately, there is great promise that an anti-inflammatory modulator targeting a cytokine storm effect may prove to be very beneficial in reducing morbidity and mortality in COVID-19 patients.
Subject(s)
COVID-19 , Cytokine Release Syndrome , COVID-19/complications , Humans , Morbidity , SARS-CoV-2 , Systemic Inflammatory Response SyndromeABSTRACT
At present, it has been noticed that some patients recovered from COVID-19 present a recurrent positive RNA test of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) after being discharged from hospitals. The purpose of the current study was to characterize the clinical features of re-hospitalized patients with recurrent SARS-CoV-2 positive results. From January 12 to April 1 of 2020, our retrospective study was conducted in China. The exposure history, baseline data, laboratory findings, therapeutic schedule, and clinical endpoints of the patients were collected. All the patients were followed until April 10, 2020. Among all COVID-19 patients included in the current study, there were 14 re-hospitalized patients due to recurrent positive tests of SARS-CoV-2 RNA. Fever (11 [78.6%]), cough (10 [71.4%]), and fatigue (7 [50.0%]) were the most common symptoms on the patient's first admission, and less symptoms were found on their second admission. The average duration from the onset of symptoms to admission to hospital was found to be 8.4 days for the first admission and 2.6 days for the second admission (P = 0.002). The average time from the detection of RNA (+) to hospitalization was 1.9 days for the first admission and 2.6 days for the second admission (P = 0.479), and the average time from RNA (+) to RNA (-) was 11.1 days for the first admission and 6.3 days for the second admission (P = 0.030). Moreover, the total time in hospital was 18.6 days for the first admission and 8.0 days for the second admission (P = 0.000). It may be necessary to increase the isolation observation time and RT-PCR tests should be timely performed on multiple samples as soon as possible.