(This information is not intended to be a substitute for the advice of a doctor or a recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the advice of a doctor for your specific condition.)

When the air we breathe contains germs, our immune system protects the lungs from infection. In fact, the bacteria and viruses that can cause pneumonia are commonly found in the air we breathe, but our body normally keeps them from entering our lungs and causing a problem. Sometimes germs can get past the defenses of the respiratory system causing pneumonia.

Pneumonia is an inflammation of the lung. Inflammation is the immune system's normal response to injury or contaminants. Germs, bacteria, and viruses are contaminants and can cause inflammation. When a person has pneumonia, lung tissue can fill with pus and other fluids. This makes it hard for oxygen to reach the bloodstream. With pneumonia, a person develops a cough and fever and it might be hard to breathe.

There are more than 50 kinds of pneumonia. Bacteria cause bacterial pneumonias. Viruses cause viral pneumonias. Fungi and other organisms can cause other types of infectious pneumonia. Pneumonia can affect one or both lungs. When it affects both lungs, it is sometimes called double pneumonia.
• Community-acquired pneumonia refers to pneumonia you get, or acquire, from your community, such as at school, work or the gym.
• Hospital-acquired or nosocomial pneumonia is a serious pneumonia acquired at a hospital or a healthcare facility.
• Aspiration pneumonia happens when anything other than air gets into the lungs. An example of this is when a person cannot stop vomit from going into the lungs. Patients with brain injury or other conditions that affect their ability to swallow are more likely to have vomit or food go down the trachea and into the lungs. When vomit, food or liquid, other than clean fresh water, enter the lungs, it causes a chemical reaction that leads to inflammation of the lungs. Often this inflammation causes bacteria to multiply and make the pneumonia worse.
• Walking pneumonia refers to a pneumonia that is mild enough so you may not even know you have it. You may be able to walk around with this type of pneumonia.

Signs and symptoms of pneumonia can be very different, depending on any other conditions you may have and what caused the infection. There are many symptoms of pneumonia, and some of them, like a cough or a sore throat, are associated with other common infections. Often, people get pneumonia after they've had the flu or an upper respiratory tract infection like a cold. Most people experience a few, but not all, of the following symptoms of pneumonia: Fever, Chills, Cough, Unusually fast breathing, Wheezing, Difficulty breathing. Less common symptoms of pneumonia include: Chest or abdominal pain, Loss of appetite, Exhaustion and Vomiting

When bacteria cause pneumonia, the person gets sick right away, along with a high fever and difficulty breathing. When a virus causes pneumonia, symptoms usually appear more gradually and may be less severe.

If you think you may have pneumonia, don't hesitate to get medical care. Severe pneumonia can be life threatening. See your doctor right away if you have any of these symptoms and they don’t go away: Cough, Shortness of breath, Chest pain that changes as you breathe, a fever — especially a fever of 39° C or higher for 2 or more days, along with chills and sweats, and if you suddenly feel worse after a cold or the flu

Once the organism causing the pneumonia is identified, a treatment plan is developed that will target the specific organism. People who have bacterial or atypical pneumonia will probably be given antibiotics to take at home. If you have this type of pneumonia, you will also need to get lots of rest and drink plenty of fluids. Drinking fluids, especially water, keeps you from becoming dehydrated and also helps loosen mucus in your lungs. There are also antiviral medications that can reduce the severity of certain viral infections if taken in the first 1 to 2 days after symptoms begin. Take all of your prescribed medications. Stopping prescribed medication too soon could cause your pneumonia to come back and could cause you to develop antibiotic-resistant bacteria. Follow the instructions that came with your medicine and take all the prescribed doses on time.

With treatment, most types of pneumonia are cured in 1-2 weeks. For severe pneumonia, it may take longer to completely recover. Even if you feel better, your lungs may still be infected. It's important to have your doctor monitor your progress.

The germs that cause many of the different types of pneumonia can be contagious and are spread through coughing and sneezing. Preventing pneumonia is always better than treating it. You can prevent pneumonia by following good hygiene habits: cough or sneeze into a tissue, use separate drinking glasses and eating utensils, wash your hands often with warm soapy water, and use alcohol based gel for handwashing when soap and water are not available.

Do not visit sick patients with pneumonia. If you have pneumonia, do not visit older people, babies or sick people. Some types of pneumonia develop when the immune system is weak. To prevent this type of pneumonia, follow these well-known measures to stay healthy and keep the immune system ready: Eat healthy, Sleep well, Avoid smoking, Exercise, Reduce stress, Do not drink alcohol in excess, and Get routine child vaccines and flu shots. Flu vaccinations are recommended since pneumonia often occurs as a complication of the flu. Pneumonia vaccinations are recommended for adults 65 and older and for those who have long-term illnesses. Flu shots are recommended annually.

(Source:  U. S. National Library of Medicine - National Institute of Health)