After infection, bacteria are exposed to several postulated stressors including mucin hypersecretion and increased osmotic pressure (Henderson et al., 2014), oxidative and nitrosative stresses (Antus, 2016) due to host responses, sublethal concentrations of antibiotics (Wozniak and Keyser, 2004), and the competition with other microorganisms (Pompilio et al., 2015). This evidence concerns the gene MUC5AC and infection.