Bloodstream infections in COVID-19 patients undergoing extracorporeal membrane oxygenation in ICU: An observational cohort study

Background: COVID-19 patients undergoing ECMO are at highly increased risk of nosocomial infections. Objectives: To study incidence, clinical outcomes and microbiological features of bloodstream infections (BSI) occurring during ECMO in COVID-19 patients. Methods: Observational prospective cohort study enrolling consecutive COVID-19 patients undergoing veno-venous-ECMO in an Italian ICU from March 2020 to March 2022. Results: In the study population of 68 patients (age 53 [49-60] years, 82% males), 30 (44%) developed blood-stream infections (BSI group) while 38 did not (N-BSI group) with an incidence of 32 events/1000 days of ECMO. In BSI group pre-ECMO respiratory support was shorter (6 [4-9] vs 9 [5-12] days, p = 0.02) and ECMO treatment was longer (18 [10-29] vs 11 [7-18] days, p = 0.03) than in N-BSI group. The overall ECMO and ICU mortality were 50% and 59%, respectively, without any inter-group difference (p = 1.00). A longer ECMO treatment was independently correlated with higher rate of BSI (p = 0.04, OR [95% CI] 1.06 [1.02-1.11]). Sixteen primary and 14 secondary infectious events were documented. Gram-positive pathogens were more common in primary than secondary BSI (88% vs 43%, p = 0.02) and Enterococcus faecalis (56%) was the most frequent one. Conversely, Gram-negative microorganisms were more often isolated in secondary rather than primary BSI (57% vs 13%, p = 0.02), with Acinetobacter baumannii (21%) and Pseudomonas aeruginosa (21%) as most represented species. The administration of Sars-CoV-2 antiviral drug showed independent correlation with a reduced rate of ICU mortality (p = 0.01, OR [95% CI] 0.22 [0.07-0.73]). Conclusions: Bloodstream infections represented a frequent complication without worsening clinical outcomes in our COVID-19 patients undergoing ECMO. Primary and secondary BSI events showed peculiar microbiological profiles.