Bacteria are the most common cause of pneumonia in adults.
Bacterial pneumonia can follow a viral infection, such as a cold or the flu (influenza). This type of pneumonia usually affects an area of the lung and is called lobar pneumonia.
The types of bacteria that cause pneumonia include:
- Streptococcus pneumoniae
- Legionella pneumophila, the cause of legionnaire’s disease, or legionellosis
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
- Haemophilus influenzae type B (Hib)
Streptococcus pneumoniae, also known as pneumococcus, is the most common cause of bacterial pneumonia in adults, called pneumococcal pneumonia. (2)
It can be prevented with a vaccine. The Centers for Disease Control and Prevention (CDC) recommends two pneumonia vaccines for adults 65 years of age and older: the pneumococcal conjugate vaccine, or Prevnar 13 (PCV13), and the polysaccharide pneumococcal vaccine, or Pneumovax 23 (PPSV23). (3)
According to the CDC:
- You should first receive a dose of pneumococcal conjugate vaccine (PCV13), followed at least one year later by a dose of pneumococcal polysaccharide vaccine (PPSV23).
- If you have previously received doses of PPSV23, the dose of PCV13 should be administered at least one year after the most recent dose of PPSV23.
- If you have already received a dose of PCV13 at a younger age, another dose is not recommended.
Mycoplasma pneumoniae Usually infects young adults who work in crowded areas, such as schools, homeless shelters or prisons. (4)
Chlamydophila pneumoniae causes mild pneumonia which usually affects people over the age of 60. (5)
Haemophilus influenzae Type B (Hib) infection can be prevented with a vaccine called a Hib vaccine. It is recommended for all children under 5 years old and is generally given to infants from 2 months of age. (6)
Most of the bacteria that cause pneumonia are pyogenic bacteria, which means they form pus, a combination of serum debris, dead bacteria, and white blood cells. A cough that produces discolored mucus in the presence of fever and shortness of breath can be a classic sign of bacterial pneumonia.
Other symptoms of bacterial pneumonia include:
- High fever
- Rapid breathing
- Pain when coughing or breathing deeply
- Shortness of breath
- Loss of appetite
Bacterial pneumonia tends to be more severe with more noticeable symptoms than other types of pneumonia.