Patients with severe Coronavirus Disease 2019 (Covid-19) pneumonia depending on mechanical ventilation are at risk of superinfections, especially infections of respiratory tract. This multicententer prospective observational study is focused on early diagnosis of respiratory tract superinfections and identification of risk factors (immunosuppressive therapy,...). Investigators will use bronchoalveolar lavage fluid (BALF) for Polymerase Chain Reaction (PCR) detection of pathogens and antigenic detection of mycoses.

This project can support the routine use of BALF and PCR diagnostics for early detection of pathogens. Data will be compared with historical cohort of patients without routine BAL.

Prospective, observational multicenter study

The inclusion criteria are as follows:

Age > 18 years Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) PCR positivity in the last 21 days Mechanical ventilation for Covid-19 pneumonia Presence of lung infiltrations on the chest X-ray or ground glass opacity, crazy paving or lung infiltrations on the chest CT Oxygenation disorder according to Acute Respiratory Distress Syndrome (ARDS) definition: Partial Pressure of Oxygen in Arterial Blood (PaO2) / fraction of inspired oxygen (FiO2) <300 mmHg with positive end expiratory pressure (PEEP) at least 5 cmH2O

The exclusion criteria are as follows:

Disagreement with the inclusion in the trial

Outcomes Primary outcome: incidence and characteristics of superinfections in patients with Covid-19.

Secondary outcome:

Markers of infection/inflammation diagnostic values for the diagnosis of a specific type of superinfection.

Comparison of the incidence of bacterial and opportunistic superinfections with a historical cohort, where the extension of diagnostics with bronchoalveolar lavage was performed only in patients who did not respond to antibacterial therapy

Size of the group of patients The number of patients enrolled in the study depends on the epidemiological situation and the number of admitted patients with severe Covid-19 disease. Investigators expect that the University Hospital at St. Anne's enrolls 75 patients and the University Hospital Brno also enrolls 75 patients. The size of the group is not relevant due to character of the study.

Monitored parameters Bronchoalveolar lavage (BAL) is the only procedure that differs from standard care. It is usually performed in patients with a suspected lung infection that does not respond to antibiotic therapy. In the study, BAL will be performed early after admission and then in 7-day intervals ( ± 1 day). This interval can be shortened to a minimum of 3 days if there are signs of a new lung infection.

Inclusion Criteria:

• Age > 18 years
• SARS-CoV-2 PCR positivity in the last 21 days
• Mechanical ventilation for Covid-19 pneumonia
• Presence of lung infiltrations on the chest X-ray or ground glass opacity, crazy paving or lung infiltrations on the chest CT
• Oxygenation disorder according to ARDS definition: PaO2 / FiO2 <300 mmHg with PEEP at least 5 cmH2O

Exclusion Criteria:

• Disagreement with the inclusion in the trial

Adults with COVID-19 ARDS on mechanical ventilation.