In the presence of 5% mucin, the infection doses were 3.0 × 106, 3.7 × 106, 3.3 × 106, 3.3 × 106, and 1.9 × 106 CFU/mouse for E. coli K12 (DA5438), QH0002, QH0004, QH0005 and QH0007, respectively. Here, MUC5AC is linked to infection.