Extensive microbiological respiratory tract specimen characterization in critically ill COVID-19 patients.

Microbial co-infections may contribute to the pulmonary deterioration in COVID-19 patients needing intensive care treatment. The present study portrays the extent of co-infections in COVID-19 ICU patients. Conventional culture, molecular detections for atypical aetiologies, QiaStat-Dx® respiratory panel V2 detecting 21 respiratory pathogens and ribosomal DNA genes 16S/18S amplicon-based microbiome analyses were performed on respiratory samples from 34 COVID-19 patients admitted to the ICU. Potential pathogens were detected in seven patients (21%) by culturing, in four patients (12%) by microbiome analysis and in one patient (3%) by respiratory panel. Among 20 patients receiving antibiotics prior to ICU admission, fungi (3 Candida albicans, 1 C. tropicalis, 1 C. dubliniensis) were cultured in 5 (15%) endotracheal aspirates. Among 14 patients who were antibiotic-naive at ICU admission, two patients (6%) had bacterial respiratory pathogens (Staphylococcus aureus, Streptococcus pseudopneumoniae) cultured in their endotracheal aspirates. Microbiome analysis recognized four potential respiratory pathogens (3 Haemophilus influenza, 1 Fusobacterium necrophorum) isolated in samples from four other patients (12%). QiaStat-Dx® respiratory panel V2 detected adenovirus in one patient (3%). The prevalence of pulmonary microbial co-infections is modest among COVID-19 patients upon admission to ICU. Microbiome analysis complements conventional microbial diagnostics in characterization of respiratory co-infections.