Final answer:
Streptococcus pneumoniae is the most common pathogen causing community-acquired bacterial pneumonia in smokers, leading to inflammation and a productive cough with bloody sputum.
Step-by-step explanation:
The most common pathogen that causes community acquired bacterial pneumonia in smokers is Streptococcus pneumoniae. Smokers have an increased risk of developing pneumonia due to the impairment of the lungs' immune defenses by components of tobacco smoke. Streptococcus pneumoniae, a gram-positive alpha hemolytic streptococcus which is part of the human respiratory tract's normal flora, tends to invade the bronchioles and alveoli, leading to a productive cough with bloody sputum. The pathogen's polysaccharide capsule and pneumolysin O virulence factors contribute to disease progression and inflammation.