NAPLEX Examination.
Practice Question # 80.
Naplex
Capsule is an adherent, usually polysaccharide surface coat (glycocalyx); however, the capsule of Bacillus anthracis is polypeptide. Not all bacteria are able to make a capsule, and those that do often do not continue to make the capsule upon culture in the lab. Antigenic differences among capsules can be used to identify strains within a single species of bacteria (e.g., Streptococcus pneumoniae, Haemophilus influenzae type b). The capsule is a major virulence factor owing to the following features:
- Acts as a barrier to toxic hydrophobic molecules
- Prevents phagocytosis of the organism by macrophages and neutrophils
- Aids in adherence of the organism to host cells and nonbiological surfaces
