1. How does an organism with a capsule such as K. pneumoniae, provide the organism with pathogenic abilities to avoid destruction by the host cell?
2. Why are infections of the upper respiratory tract milder as compared to the infections of the lower respiratory tract?
The key point to consider when discussing the pathogenic abilities imparted by the capsule is the prevention of phagocytosis. Phagocytes (the cells that engulf foreign particles) are impeded or inhibited by polysaccharides on the surface of the capsule. This means that K. pneumoniae are able to survive and spread while other bacteria would be engulfed by the immune cells.
The following paper includes a nice overview of the importance of the capsule:
I've highlighted some points below:
- The capsule is ...
This solution, containing over 300 words and references to two peer-reviewed articles, outlines the importance of capsules for pathogenic microbes. Additionally, comparison between upper and lower respiratory tract infections are made with respect to medical importance.