Saliva as a tool for detecting SARS-CoV-2 , the link between SARS-CoV-2 viral load and elevated IL-6 in critically ill patients, and the link between thrombocytopenia and COVID-19 in-hospital mortality
By Denise Baez
NEW YORK -- April 20, 2020 -- In today’s DG Alert, we cover detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in saliva samples, the link between SARS-CoV-2 viral load and elevated interleukin 6 (IL-6) in critically ill patients, and the link between thrombocytopenia and coronavirus disease 2019 (COVID-19) in-hospital mortality.
According to a study published in the Journal of Infection, saliva is a reliable tool to detect SARS-CoV-2.
Lorenzo Azzi, MD, University of Insubria, Varese, Italy, and colleagues analysed salivary samples of 25 patients with COVID-19 and compared the results with their clinical and laboratory data.
SARS-CoV-2 was detected in all 25 patients’ first salivary swab. Eight patients underwent a second salivary swab after 4 days, and the results were consistent with the first analysis, without relevant differences in variable threshold cycles (Ct).
“A striking feature was highlighted in 2 patients who showed positive salivary results on the same days when their pharyngeal or bronchoalveolar swabs proved to be negative,” the authors wrote. “These results reinforce the hypothesis that saliva is a reliable tool to be used in qualitative COVID-19 diagnosis through the reverse transcriptase-polymerase chain reaction (RT-PCR) procedure.”
Another study, published in Clinical Infectious Diseases, showed that detectable serum SARS-Cov-2 RNA(RNAaemia) in patients with COVID-19 was associated with elevated IL-6 concentration and poor prognosis.
According to Xiaohua Chen, General Hospital of Central Theater Command, Wuhan, China, and colleagues collected serum samples and throat-swabs from 48 patients with COVID-19 and extracted RNA from all patients. RT-PCR was used to determine the viral load by using a SARS-CoV-2 nucleic acid detection kit.
After analysing the clinical characteristics of all patients, RNAaemia was diagnosed only in critically ill patients with COVID-19, and seemed to reflect the severity of the disease. Furthermore, the level of inflammatory cytokine IL-6 in critically ill patients increased significantly, almost 10 times that in other patients. More importantly, the extremely high IL-6 level was closely correlated with the detection of RNAaemia (R = 0.902).
“Sharply increased IL-6 level was observed in critically ill patients, which was almost 10 times that of severe patients, and all deaths exhibited extremely high IL-6 value, suggesting that IL-6 might be an important biomarker to judge the poor prognosis of patients with COVID-19,” the authors wrote. “The extremely high level of IL-6 is a hallmark and important driving force of cytokine storm, which may cause multiple organ dysfunction in critically ill patients.”
“Because the elevated IL-6 may be part of a larger cytokine storm which could worsen outcome, IL-6 could be a potential therapeutic target for critically ill patients with an excessive inflammatory response.”
Lastly, a study published in Journal of Thrombosis and Haemostasis showed that thrombocytopenia is common in patients with COVID‐19, and is associated with increased risk of in‐hospital mortality.
Xiaobo Yang, MD, Tongji Medical College, Wuhan, and colleagues retrospectively analysed data from 1,476 patients with COVID-19 treated at Jinyintan Hospital in Wuhan. Of the patients, 238 (16.1%) died. Compared with survivors, non‐survivors were older, were more likely to have thrombocytopenia, and had lower nadir platelet counts.
Among the patients, 306 (20.7%) had thrombocytopenia. The in‐hospital mortality was 92.1% for patients with nadir platelet count 0 to 50, 61.2% for patients with counts 50 to 100, 17.5% for patients with platelet count 100 to 150, and 4.7% for patients with platelet counts ≥150.
“Thrombocytopenia is common in patients with COVID‐19, and it is associated with increased risk of in‐hospital mortality,” the authors concluded. “The lower the platelet count is, the higher the mortality becomes.”
Popular with Other Subscribers