Gram Negative Cocci
Several Neisseria species are a part of the normal flora (commensals) of the human upper respiratory tract. Which of the following statements accurately describes the significance of these bacteria?
|A||As a part of the normal flora, Neisseriae provide a natural immunity in local host defense|
|B||As a part of the respiratory flora, they are the most common cause of acute bronchitis and pneumonia|
|C||Commensal bacteria stimulate a cell-mediated immunity (CMI)|
|D||Commensal Neisseriae in the upper respiratory tract impede phagocytosis by means of lipoteichoic aciD|
The normal or usual flora seldom cause disease in humans, except the several species that may be opportunistic in the right circumstances.
a. One mechanism that has been suggested as to how the normal flora help to protect humans from pathogenic strains of bacteria is to stimulate the immune system to produce antibodies (or CMI) that would recognize related pathogens and inhibit their growth.
b. An unexplained component of this mechanism is how the normal flora continue to exist as part of the body flora in spite of these immune mechanisms.