Microbial community composition and patient reported symptoms in Cystic Fibrosis (CF).

Objective To determine the relationship between microbial community composition and patient reported symptoms in CF. Methods Data from patients enrolled in a study to determine the potential role of anaerobes in CF pulmonary infection were analysed (10/NIR01/41). On enrolment, patients completed a CFQ-R questionnaire1 and provided an expectorated sputum sample whilst clinically stable. Scores for the respiratory symptoms domain were summarised. Community profiles were determined by sequencing of the 16S rRNA gene on the Illumina MiSeq. Ecological parameters (richness, Shannon diversity, evenness, dominance) were determined for each sample. Total bacterial and P. aeruginosa (PA) abundance was determined by qPCR. Relationships were assessed using Pearson correlation coefficient. Quantitative counts of PA (copies/ml, log transformed) were summarised and defined in tertiles (0-2.62; 2.63-5.24; 5.25-7.8). Differences between tertiles were assessed using one way ANOVA. p< 0.05=statistical significance. Results Data from 96 patients was analysed (mean [SD] age 29.4 [13.6]; female:male 39:57; mean [SD] FEV1%pred 67.4 [21.4]). There was no relationship between respiratory symptoms and diversity, dominance or richness (r=-0.11 to 0.14; p>0.05). Respiratory symptoms correlated only weakly with evenness (r=-0.22; p=0.03). Across PA tertiles, there was a significant difference between diversity (p=0.007) and richness (p=0.001), with a lower diversity and richness linked to a higher count. However, there was no difference in respiratory symptoms domain across PA tertiles (p=0.65). Conclusion In agreement with other studies2, there was a poor relationship between microbial community characteristics and patient reported respiratory symptoms. Further analysis of these relationships longitudinally during clinical stability and exacerbation are required. 1. Quittner et al. (2005) 2. Whelan et al. (2017) Funding: HSC R&D, PHA (NI), MRC & NIH through a US-Ireland Partnership Grant.