Causes of Pneumonia

Encourage friends and loved ones with certain health conditions, like diabetes and asthma, to get vaccinated against the flu and bacterial pneumonia.
When bacteria, viruses or, rarely, fungi living in your nose, mouth, sinuses, or the environment spread to your lungs, you can develop pneumonia or other infections. You can catch the bacteria or viruses from people who are infected with them, whether they are sick or not.

Types of Pneumonia

You may have heard of community-acquired pneumonia (CAP). When someone develops pneumonia in the community (not in a hospital), it's called CAP.
Pneumonia developed during or following a stay in a healthcare facility (like hospitals, long-term care facilities, and dialysis centers) is called healthcare-associated pneumonia (HCAP), which includes hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP).
In the United States, the most common bacterial cause of pneumonia is Streptococcus pneumoniae (pneumococcus) and the most common viral causes are influenza, parainfluenza, and respiratory syncytial viruses. In children younger than 1 year of age, respiratory syncytial virus (RSV) is the most common cause of pneumonia. Other common bacterial and viral causes of pneumonia in the United States include Staphylococcus aureus and adenovirus. Pneumocystis jirovecii, a fungus formerly known as Pneumocystis carinii, is a common cause of pneumonia in patients with AIDS.

Reduce Your Risk

Pneumonia can be prevented with vaccines. Following good hygiene practices can also help prevent respiratory infections. This includes washing your hands regularly, cleaning hard surfaces that are touched often (like doorknobs and countertops), and coughing or sneezing into a tissue or into your elbow or sleeve. You can also reduce your risk of getting pneumonia by limiting exposure to cigarette smoke and treating and preventing conditions like diabetes and HIV/AIDS.
In the United States, there are several vaccines that prevent infection by bacteria or viruses that may cause pneumonia. These vaccines include:

• Pneumococcal,
• Haemophilus influenzae type b (Hib),
• Pertussis (whooping cough),
• Varicella (chickenpox),
• Measles, and
• Influenza (flu) vaccine.