Analysis of the nasal microbiome in long-term survivors after lung transplantation with a good allograft function

Introduction: Long-term survival after lung transplantation (LT) is limited to the appearance of different complications, for example infections, which directly increase the mortality but also stimulate the development of chronic lung allograft dysfunction (CLAD). However, there is a small number of LT patients which are long-term survivors with good allograft function (LTS). The objective of this project is to analyze the nasal bacterial microbiome in CLAD and LTS patients to establish if upper respiratory tract microbiomes differ between both groups. Patients and Methods: Fifty one double lung transplant recipients were included in this multicenter cross-sectional study: 25 patients with CLAD and 26 patients with a stable allograft function 10 years after lung transplantation (LTS). A nasal swab was obtained from all of them and the bacterial DNA was extracted to prepare an amplicon library of the V4 16S rRNA gene through PCR to ultimately be sequenced. The bioinformatics and statistical analyses were performed using the pipeline QIIME 1.9.1 and the R 3.4.3 program. Results: Both groups of patients had significant differences in both bacterial composition and abundance. CLAD patients had a statistically significant increase of the Firmicutes phylum (FDR = 0.014) while LTS presented a statistically significant increase of the Actinobacteria phylum (FDR = 0.014) Conclusion: The nasal microbiome in LTS patients is different from the CLAD patients microbiome, being the LTS enriched with Actinobacteria and the CLAD with Firmicutes.