Selection of IgA coated microbiome from Endotracheal Aspirate.

<bold>Introduction:</bold> Ventilator-associated pneumonia (VAP) occurred as the result of the dysbiosis observed in patients receiving IMV. Secretory IgA could be involved in the regulation and selection of commensal microorganisms and the establishment of mutualistic host–microbial interactions. Our hypothesis is that patients who developed VAP have lower levels of secretory IgA-coated microbiota in respiratory secretions, which leads to a higher inflammatory environment, dysbiosis, and an increase in pathogenic bacteria. <bold>Methods:</bold> The respiratory sample was mechanically and chemically disrupted, filtered and centrifuged. Bacteria were separated by centrifugation and resuspended. Part of this suspension was reserved as a total bacterial sample unstained, and the rest was stained with a recombinant Anti-IgA PE human antibody, and it was sorted by Magnetic Activation Cell Sorting (MACS). Unstained, unsorted and negative and positive fraction of the sorted bacterials suspensions were analysed by flow cytometry. <bold>Results:</bold> The preliminary results indicates that part of the microbiome present in endotracheal aspirate samples have IgA coated bacteria. The positive fraction of the sorted bacteria has an enrichment in IgA coated bacteria compared with the unsorted bacteria and the negative fraction of the sorted bacteria. These results are shown in Fig1. <fig><object-id>erj;66/suppl_69/PA2865/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusions:</bold> MACS sorting can be used to select IgA coated bacteria from endotracheal aspirate samples.