Beech, Augusta; orcid: 0000-0002-2690-5364; email: augusta.beech@manchester.ac.ukLea, Simon; orcid: 0000-0003-3700-1886; email: Simon.lea@manchester.ac.ukLi, Jian; email: Jian.Li@manchester.ac.ukJackson, Natalie; email: njackson@meu.org.ukMulvanny, Alex; email: amulvanny@meu.org.ukSingh, Dave; email: dsingh@meu.org.uk2021-09-292021-09-292021-09-27Biomedicines, volume 9, issue 10, page e1337http://hdl.handle.net/10034/625980From MDPI via Jisc Publications RouterHistory: accepted 2021-09-22, pub-electronic 2021-09-27Publication status: PublishedFunder: AstraZeneca; Grant(s): ESR-16-11869Background: Chronic obstructive pulmonary disease (COPD) inflammatory endotypes are associated with different airway microbiomes. We used quantitative polymerase chain reaction (qPCR) analysis of sputum samples to establish the bacterial load upper limit in healthy controls; these values determined the bacterial colonisation prevalence in a longitudinal COPD cohort. Bacteriology combined with sputum inflammatory cells counts were used to investigate COPD endotypes. Methods: Sixty COPD patients and 15 healthy non-smoking controls were recruited. Sputum was analysed by qPCR (for Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Psuedomonas aeruginosa) and sputum differential cell counts at baseline and 6 months. Results: At baseline and 6 months, 23.1% and 25.6% of COPD patients were colonised with H. influenzae, while colonisation with other bacterial species was less common, e.g., S. pneumoniae—1.9% and 5.1%, respectively. H. influenzae + ve patients had higher neutrophil counts at baseline (90.1% vs. 67.3%, p 0.01), with similar results at 6 months. COPD patients with sputum eosinophil counts ≥3% at ≥1 visit rarely showed bacterial colonisation. Conclusions: The prevalence of H. influenzae colonisation was approximately 25%, with low colonisation for other bacterial species. H. influenzae colonisation was associated with sputum neutrophilia, while eosinophilic inflammation and H. influenzae colonisation rarely coexisted.Licence for this article: https://creativecommons.org/licenses/by/4.0/chronic obstructive pulmonary diseaseinflammatory endotypesHaemophilus influenzaeeosinophileosinophilic inflammationneutrophilneutrophilic inflammationsputumairway colonisationarticle2021-09-29