Final answer:
The most common agent of bacterial pneumonia is Streptococcus pneumoniae, and the initial treatment typically involves β-lactam antibiotics like penicillin. Due to rising antibiotic resistance, alternative medications may be used, along with recommended pneumococcal vaccines for certain age groups.
Step-by-step explanation:
The most common pneumonia bug responsible for community-acquired bacterial pneumonia is Streptococcus pneumoniae. This gram-positive bacteria is part of the normal flora of the human respiratory tract and typically presents as a pair of lancet-shaped cells. It can cause infection in the bronchioles and alveoli, leading to symptoms like a productive cough with bloody sputum. The pneumococci have virulence factors such as pneumolysin O, which is detrimental to the host cells and stimulates an inflammatory response.
The best first step in treatment is the administration of β-lactam antibiotics like penicillin. However, due to increasing resistance to β-lactams, alternative treatments such as macrolides and fluoroquinolones may be prescribed. Preventative measures include two types of pneumococcal vaccines: PCV13 and PPSV23, particularly recommended for children under 2 years and adults over 65 years.