Mucous membranes are barriers against colonization and growth of microorganisms.

1.   Mucous membranes are barriers against colonization and growth of microorganisms. However, mucous membrane, for example in the throat and gut, are colonized with a variety of different microorganism, some of which are potential pathogens. Explain how these potential pathogens are controlled under normal circumstances. Then describe at least one set of circumstances that might encourage pathogenicity.
2.   What psychological symptoms might the reduction of normal flora in the GI tract produce in the host? Infection by opportunistic pathogens often follows long-term antimicrobial therapy. Many of these post-therapeutic infections are caused by the same microorganisms that produce opportunistic infections in individuals with AIDS. What pathogens might be involved? Why are individuals who have undergone antibiotic therapy particularly susceptible to these pathogens?