Final answer:
Streptococcus pneumoniae is the main cause of pneumococcal pneumonia and can also cause meningitis and other diseases, while Mycoplasma pneumoniae is known for causing milder atypical pneumonia.
Step-by-step explanation:
Streptococcus pneumoniae, commonly known as pneumococcus, is a significant causative agent of respiratory diseases such as pneumonia, meningitis, septicemia, and others. Typically found as part of the normal microbiota in the human respiratory tract, its pathogenicity arises due to various virulence factors like the polysaccharide capsule and pneumolysin O. Unlike other streptococci, S. pneumoniae appears as diplococci under microscopic observation and does not form long chains.
Mycoplasma pneumoniae causes a milder form of pneumoniae known as atypical pneumonia or walking pneumonia, mostly in crowded environments like schools and military barracks. This bacterium, lacking a cell wall, notably attaches to and damages epithelial cells, leading to an impaired ciliary function of the respiratory tract.
Understanding these pathogens is crucial for the diagnosis and treatment of respiratory infections, including pneumococcal meningitis and bacterial pneumonia. While Staphylococcus aureus is another well-known bacterium capable of causing a variety of infections, it is not typically linked with atypical pneumonia as Mycoplasma pneumoniae is.