The impact of bacterial superinfections on the outcome of critically ill patients with COVID-19 associated acute respiratory distress syndrome (ARDS) – a single-centre, observational cohort study

Introduction:
Bacterial superinfections are common in severely ill COVID-19 patients and could be associated with a significant increase in morbidity and mortality.

Material and methods:
We assessed 29 critically ill patients treated in a university hospital’s intensive care unit (ICU). Each patient required mechanical ventilation due to COVID-19-induced acute respiratory distress syndrome (ARDS). Fifteen patients who required venovenous extracorporeal membrane oxygenation (VV-ECMO) support (ECMO group) were compared to a control group (CON group) of 14 individuals without ECMO. This study aimed to assess the prevalence of superinfection in both studied groups. Moreover, we evaluated mortality, length of stay in the ICU, positive culture results, antibiotics used during treatment, and the impact of immunomodulatory drugs on secondary infections.

Results:
We did not find a difference in the number of superinfections between the ECMO and CON groups (11 vs. 10, P = 1.0). The mortality rate was 67% in the ECMO group and 64% in the CON group (P = 1.0). The patients in both groups had similar numbers of positive culture results and days in the ICU prior to the detection of a positive culture. Antibiotics were administered to ten patients in the ECMO and eight patients in the CON group. The mortality rate was 81% in patients with superinfection versus 25% in those without co-infection (P = 0.009). We found a negative impact of urea concentration on mortality in our cohort, with an odds ratio of 0.942 (0.891–0.996, P = 0.034).

Conclusions:
Our results suggest that bacterial superinfection in COVID-19 patients negatively impacted survival in the ICU. VV-ECMO support in COVID-19 patients does not seem to improve the outcomes of patients with severe ARDS.