Pathogen patterns in viral ARDS on V-V ECMO: a single-center experience

BACKGROUND: Viral acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure requiring veno-venous extracorporeal membrane oxygenation (V-V ECMO). Pulmonary bacterial superinfections, pulmonary aspergillosis, and viral infections or reactivations frequently occur, but data on their incidence, timing, and microbiological spectrum remain limited. We analyzed infectious complications in a large cohort of V-V ECMO-treated patients with viral ARDS. METHODS: We retrospectively evaluated all patients treated at University Hospital Regensburg (UKR) requiring V-V ECMO for COVID-19 (March 2020-May 2022) or influenza (May 2012-December 2022). RESULTS: We included 147 COVID-19 patients (median age 55.3 years; 77% male; SOFA score 9; V-V ECMO duration 23 days) and 72 influenza patients (median age 55.3 years; 53% male; SOFA score 13; V-V ECMO duration 16 days). COVID-19 patients showed higher cumulative incidences of pulmonary bacterial superinfection (61% vs 35%), aspergillosis (33% vs. 22%), CMV reactivation (18%vs. 4%) and HSV reactivation (49% vs. 26%), however incidence-density rates were comparable between groups with incidence rate ratios (IRR) of 1.10, 0.93, 1.36 and 1.12, respectively. First bacterial pulmonary infection occurred a median of 2 days after V-V ECMO initiation in COVID-19 and 1 day before initiation in influenza patients. Predominant bacterial pathogens were Klebsiella spp. (28%), Staphylococcus aureus (27%) and Escherichia coli (11%) in COVID-19, and Staphylococcus aureus (25%) and Streptococcus pneumoniae (25%) in influenza. CONCLUSION: Patients with COVID-19 requiring V-V ECMO showed a distinct trajectory of infectious complications compared to Influenza, particularly bacterial, HSV, CMV, and fungal infections, highlighting their infectious burden.