Development and characterisation of a multi-species COPD biofilm

Bacteria can persist in the lungs of chronic obstructive pulmonary disease (COPD) patients for a number of months. It is hypothesised that this is possibly due to the formation of biofilms, which may also be responsible for recurrent acute exacerbations. Using conventional biofilm assays, microscopy, confocal laser scanning microscopy and molecular quantification techniques, we sought to develop and characterise a multi-species biofilm representative of the COPD lung. Using this model, we aimed to study how antibiotics influence microbial composition and modulate the host immune response. Scanning electron microscopy revealed that inter-kingdom biofilms possess a more complex structure compared to single species biofilms. Whilst experiencing shifts in overall composition, this added biofilm complexity provided increased tolerance to antimicrobials such as erythromycin and amoxicillin. Stimulation of alveolar epithelial cells with multi-species biofilm supernatants revealed increased production of the pro-inflammatory cytokines IL-1β and TNF-α. Labelling biofilms with microbe-specific fluorescent probes allowed for easy identification of microbes within a complex multi-species biofilm. This study highlights the need to utilise multi-species biofilms to study the pathogenesis of disease and emphasises the importance of selecting appropriate antimicrobial therapies.