Pulmonary superinfection diagnosed with bronchoalveolar lavage at intubation in COVID patients: A Swedish single-centre study.

Background: Patients with severe coronavirus disease 2019 (COVID) pneumonia and acute respiratory distress syndrome (C-ARDS) on invasive mechanical ventilation (IMV) have been found to be prone to having other microbial findings than severe acute respiratory syndrome coronavirus 2 (SARS-2)-CoV-19 in the bronchoalveolar lavage (BAL) fluid at intubation causing a superinfection. These BAL results could guide empirical antibiotic treatment in complex clinical situations. However, there are limited data on the relationship between microbial findings in the initial BAL at intubation and later ventilator-associated pneumonia (VAP) diagnoses.

Objective: To analyse the incidence of, and microorganisms responsible for, superinfections in C-ARDS patients at the time of first intubation through microbial findings in BAL fluid. To correlate these findings to markers of inflammation in plasma and later VAP development.

Design: Retrospective single-centre study.

Setting: One COVID-19 intensive care unit (ICU) at a County Hospital in Sweden during the first year of the pandemic.

Patients: All patients with C-ARDS who were intubated in the ICU.

Results: We analysed BAL fluid specimens from 112 patients at intubation, of whom 31 (28%) had superinfections. Blood levels of the C-reactive protein, procalcitonin, neutrophil granulocytes, and lymphocytes were indistinguishable between patients with and without a pulmonary superinfection. Ninety-eight (88%) of the patients were treated with IMV for more than 48 h and of these patients, 37% were diagnosed with VAP. The microorganisms identified in BAL at the time of intubation are normally found at the oral, pharyngeal, and airway sites. Only one patient had an indistinguishable bacterial strain responsible for both superinfection at intubation and in VAP.

Conclusions: One fourth of the patients with C-ARDS had a pulmonary superinfection in the lungs that was caused by another microorganism identified at intubation. Routine serum inflammatory markers could not be used to identify this complication. Microorganisms located in BAL at intubation were rarely associated with later VAP development.