MUC5B and cystic fibrosis: The near ubiquitous presence of mucin-fermenting anaerobes in sputum [5, 27, 28, this study], coupled with numerous studies demonstrating that the respiratory mucins MUC5B and MUC5AC are degraded in CF patients compared to healthy controls [18,39] supports the idea that bacterial mucin degradation is commonplace within the CF airways.