Geographical differences in the airway microbiota of COPD patients across the UK

<bold>Introduction:</bold> The lung microbiota differs between populations across continents however, there is little known about how much the microbiota varies within a country. The aim of this study was to investigate variation in the microbiota within a country. <bold>Methods:</bold> Sputum samples were collected from moderate to severe COPD patients from 9 centres in the UK. Patients were clinically stable with no antibiotic or corticosteroid treatment for 4 weeks. DNA extraction and LoopSeq long read 16S rRNA gene sequencing was performed. The COPD microbiota was compared between the centres as well as centres grouped into 5 geographical regions. Alpha and beta-diversity were measured to assess differences in the microbiota at species and genus level. <bold>Results:</bold> Sputum samples were collected from 162 patients. At species level the prevalence of <italic>Haemophilus influenzae</italic>, <italic>Rothia mucilaginosa</italic> and <italic>Streptococcus salivarius</italic> was 49% (80/162), 96% (156/162) and 95% (154/162) of the patients respectively. There were significant differences in Bray-Curtis beta-diversity between the nine centres at both species (p=0.04) and genus level (p=0.021). There was no significant difference in alpha-diversity between the nine centres at both species and genus level. Random forest analysis identified <italic>Parvimonas</italic> and <italic>Prevotella</italic> as the most discriminating taxa between centres. We observed no difference in beta-diversity when comparing different regions. There was a significant difference in Chao1 alpha-diversity between the 5 regions at species (p=0.030) and genus level (p=0.008). Shannon and Simpson alpha-diversity metrics were not significant. <bold>Conclusion:</bold> We demonstrate heterogeneity in the COPD lung microbiota across 9 centres in the UK.