Final answer:
Bacterial pneumonia, where bacteria can be seen in the alveoli, is most commonly caused by Streptococcus pneumoniae, H. influenzae, and Mycoplasma pneumoniae. Streptococcus pneumoniae is the leading cause, while in hospital settings or among patients with specific conditions like cystic fibrosis, other bacteria like Klebsiella pneumoniae and Pseudomonas aeruginosa become more prevalent.
Step-by-step explanation:
Pneumonia that shows the presence of bacteria in the alveoli is known as bacterial pneumonia. This type of pneumonia can be caused by various bacteria with the most prevalent being Streptococcus pneumoniae, H. influenzae, and Mycoplasma pneumoniae. Among these, Streptococcus pneumoniae, or pneumococcal pneumonia, is the leading cause of community-acquired bacterial pneumonia and is characterized by symptoms such as a productive cough with bloody sputum. This occurs as the bacteria cause the alveoli to fill with an exudate rich in neutrophils and red blood cells, interfering with normal gas exchange.
Other common opportunistic bacteria causing healthcare-associated pneumonia include Klebsiella pneumoniae and Staphylococcus aureus. In different contexts, such as in individuals with cystic fibrosis or hospitalized patients, Pseudomonas aeruginosa can cause serious pneumonia as well. In the case of cystic fibrosis, the bacteria thrive in excess dried mucus within the lungs due to a defect in the cystic fibrosis transmembrane receptor (CFTR).