MUC5AC and bacterial infectious disease: In a diseased state, such as bacterial infection, owing to inflammation, excess mucin is secreted by the goblet cells as a protective measure with infiltrating white blood cells [12], accumulation of DNA fragments from dead cells and other solids along with sodium, chloride and bicarbonate imbalance [13] that results in loss of water with the secretion becoming thick and purulent (bacterial infection), which eventuates in the reduction or absence of ciliary clearance [14].