An excessive inflammatory response to SARS-CoV-2 is thought to be a major cause of disease severity and mortality in patients with COVID-19. Longitudinal analysis of cytokine release can expand our understanding of the initial stages of disease development and help to identify early markers serving as predictors of disease severity. In this study, we performed a comprehensive analysis of 46 cytokines (including chemokines and growth factors) in the peripheral blood of a large cohort of COVID-19 patients (n=444). The patients were classified into five severity groups. Longitudinal analysis of all patients revealed two groups of cytokines, characterizing the “early” and “late” stages of the disease course and the switch between type 1 and type 2 immunity. We found significantly increased levels of cytokines associated with different severities of COVID-19, and levels of some cytokines were significantly higher during the first three days from symptom onset (DfSO) in patients who eventually required intensive care unit (ICU) therapy. Additionally, we identified nine cytokines, TNF-α, IL-10, MIG, IL-6, IP-10, M-CSF, G-CSF, GM-CSF, and IFN-α2, that can be used as good predictors of ICU requirement at 4-6 DfSO.

The ongoing worldwide COVID-19 pandemic caused by SARS-CoV-2 has had serious impacts on not only the health care system but also all sectors of the economy. Thanks to the adoption of various epidemiological measures, a significant reduction in new cases of infection has been achieved. However, there are still "hotspots", such as healthcare settings focused on treating patients with COVID-19, which are characterized by the risk of nosocomial transmission among health care workers, patients, and visitors. The proper monitoring and timely detection of pathogens in a hospital environment will help prevent further spread of coronavirus infection. In this study, we collected samples from the air and surface swabs at the First Moscow Infectious Diseases Hospital to study the spread of the SARS-CoV-2 in various hospital locations. More than 130 aerosol and surface samples were collected and analysed by RT-PCR. We detected viral contamination of the air in the intensive care unit (ICU) but not in the respiratory infection department where less severe patients are treated. The concentration of SARS-CoV-2 RNA was low, consisting of less than one copy per litre of air. The contact surfaces in both departments were contaminated with SARS-CoV-2. Considering the possible transmission of SARS-CoV-2 through fomites, these results indicate the need to strictly follow personal hygiene rules as well as wear personal protective equipment to prevent disease spread.

Brucellosis is an infectious quarantine zoonotic disease caused by bacteria of the genus Brucella, among which B. melitensis, B. abortus, and B. suis have pathogenic potential, causing a severe and often chronic course of the disease. Laboratory diagnostics is crucial for the detection of human cases, since the clinical symptoms of human brucellosis are variable and nonspecific. Laboratory diagnosis of brucellosis is based on three different approaches: direct bacteriological method, indirect method using serological and allergic tests and direct express method in different formats of molecular PCR. Despite the accumulated experience of using serological tests and the highly sensitive PCR method, the isolation of brucella culture is considered the "gold standard" in the laboratory diagnosis of brucellosis due to its clinical and epidemiological relevance. The currently available automated systems of the bacteriological method have increased its sensitivity and shortened the detection time of brucella species. The main limitations of serological tests are the lack of general interpretation criteria, low specificity due to cross-reactions with other bacteria and low sensitivity at an early stage of the disease. At the same time, in Russia, serological tests account for more than 99% of all laboratory tests and remain the main diagnostic tool. This is due to their inexpensive and convenient use at the place of medical care in endemic areas and high negative prognostic value. PCR in various formats of rapid tests diagnoses the DNA of the pathogen in a few hours with high sensitivity and specificity. Nevertheless, a positive PCR result requires careful interpretation and does not necessarily indicate an active infection. For the convenience of using diagnostic approaches to brucellosis in practical medicine and determining the activity of the infectious process, it is necessary to improve diagnostics and develop express methods. The review shows both the most routine and modern laboratory methods currently available for laboratory diagnosis of brucellosis.

Introduction. The study of the mechanisms of transmission of the SARS-CoV-2 virus is the basis for building a strategy for anti-epidemic measures in the context of the COVID-19 pandemic. Understanding in what time frame a patient can spread SARS-CoV-2 is just as important as knowing the transmission mechanisms themselves. This information is necessary to develop effective measures to prevent infection by breaking the chains of transmission of the virus. The aim of the work is to identify the infectious SARS-CoV-2 virus in patient samples in the course of the disease and to determine the duration of virus shedding in patients with varying severity of COVID-19. Materials and methods. In patients included in the study, biomaterial (nasopharyngeal swabs) was subjected to analysis by quantitative RT-PCR and virological determination of infectivity of the virus. Results. We have determined the timeframe of maintaining the infectivity of the virus in patients hospitalized with severe and moderate COVID-19. Based on the results of the study, we made an analysis of the relationship between the amount of detected SARS-CoV-2 RNA and the infectivity of the virus in vitro in patients with COVID-19. The median time of the infectious virus shedding was 8 days. In addition, a comparative analysis of different protocols for the detection of the viral RNA in relation to the identification of the infectious virus was carried out. Conclusion. The obtained data make it possible to assess the dynamics of SARS-CoV-2 detection and viral load in patients with COVID-19 and indicate the significance of these parameters for the subsequent spread of the virus and the organization of preventive measures.

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