Due to limited data on the link between gut barrier defects (leaky gut) and neutrophil extracellular traps (NETs) in coronavirus disease 2019 (COVID-19), blood samples of COVID-19 cases—mild (upper respiratory tract symptoms without pneumonia; n = 27), moderate (pneumonia without hypoxia; n = 28), and severe (pneumonia with hypoxia; n = 20)—versus healthy control (n = 15) were evaluated, together with in vitro experiments. Accordingly, neutrophil counts, serum cytokines (IL-6 and IL-8), lipopolysaccharide (LPS), bacteria-free DNA, and NETs parameters (fluorescent-stained nuclear morphology, dsDNA, neutrophil elastase, histone–DNA complex, and myeloperoxidase–DNA complex) were found to differentiate COVID-19 severity, whereas serum (1→3)-β-D-glucan (BG) was different between the control and COVID-19 cases. Despite non-detectable bacteria-free DNA in the blood of healthy volunteers, using blood bacteriome analysis, proteobacterial DNA was similarly predominant in both control and COVID-19 cases (all severities). In parallel, only COVID-19 samples from moderate and severe cases, but not mild cases, were activated in vitro NETs, as determined by supernatant dsDNA, Peptidyl Arginine Deiminase 4, and nuclear morphology. With neutrophil experiments, LPS plus BG (LPS + BG) more prominently induced NETs, cytokines, NFκB, and reactive oxygen species, when compared with the activation by each molecule alone. In conclusion, pathogen molecules (LPS and BG) from gut translocation along with neutrophilia and cytokinemia in COVID-19-activated, NETs-induced hyperinflammation.

Human pythiosis is associated with poor prognosis with significant mortality caused by Pythium insidiosum. Antimicrobials’ in vitro and in vivo results against P. insidiosum are inconsistent. Although antimicrobials are clinically useful, they are not likely to achieve therapeutic success alone without surgery and immunotherapy. New therapeutic options are therefore needed. This non-exhaustive review discusses the rationale antimicrobial therapy, minimum inhibitory concentrations, and efficacy of antibacterial and antifungal agents against P. insidiosum. This review further provides insight into the immunomodulating effects of antimicrobials that can enhance the immune response to infections. Current data support using antimicrobial combination therapy for the pharmacotherapeutic management of human pythiosis. Also, the success or failure of antimicrobial treatment in human pythiosis might depend on the immunomodulatory effects of drugs. The repurposing of existing drugs is a safe strategy for anti-P. insidiosum drug discovery. To improve patient outcomes in pythiosis, we suggest further research and a deeper understanding of P. insidiosum virulence factors, host immune response, and host immune system modification by antimicrobials.

The pathogenic oomycete Pythium insidiosum causes a fatal infectious illness known as pythiosis, impacting humans and certain animals in numerous countries in the tropics and subtropics. Delayed diagnosis is a primary factor contributing to the heightened morbidity and mortality associated with the disease. Several new serodiagnostic methods have been developed to improve the identification of pythiosis. However, these assays provide only indirect evidence of pythiosis and are not readily available in the commercial market. Here, we have developed an affordable point-of-care test (POCT) kit based on an immunochromatographic assay to detect P. insidiosum antigens directly. Our recent findings reveal that the lateral flow sandwich immunological testing cassette can accurately identify vascular pythiosis antigens using a small volume of patient’s plasma, accomplishing diagnostic efficiency, with a limit of detection (LOD) of 8 ng/mL. This prototype cartridge represents a significant stride toward advancing enriched POCT for pythiosis serodiagnosis.

The pathogenic oomycete Pythium insidiosum causes a fatal infectious illness known as pythiosis, impacting humans and certain animals in numerous countries in the tropics and subtropics. Delayed diagnosis is a primary factor contributing to the heightened morbidity and mortality associated with the disease. Several new serodiagnostic methods have been developed to improve the identification of pythiosis. However, these assays provide only indirect evidence of pythiosis and are not readily available in the commercial market. Here, we have developed an affordable point-of-care test (POCT) kit based on an immunochromatographic assay for the direct detection of P. insidiosum antigens. Our recent findings reveal that the lateral flow sandwich immunological testing cassette can accurately identify vascular pythiosis antigens using a small volume of patient’s plasma, accomplishing 100% accuracy and a limit of detection (LOD) of 8 ng/mL. This prototype cartridge represents a significant stride toward the advancement of enriched POCT for pythiosis serodiagnosis.