Pneumonia is an inflammation (swelling) of the air sacs (called alveoli) in the lungs, most commonly due to an infection which may be caused by bacteria, viruses, or fungi (infrequently). There are also a few non-infectious types of pneumonia that are caused by inhaling foreign matter or toxic substances into the lungs. It affects one or both lungs.
At the end of the breathing tubes in your lungs are clusters of tiny air sacs. If you have pneumonia, these tiny sacs called alveoli, become inflamed and fill up with fluid or pus, making it difficult to breathe.
You may cough, run a fever, and have hard time breathing. For most people, pneumonia can be treated at home. It often clears up in 2 to 3 weeks. But older adults, babies, and people with other diseases can become very ill. They may need to be in the hospital.
You can get pneumonia in your daily life, such as at school or work. You can also get it when you are in a hospital or nursing home, and this case, it may be more severe because you already are ill.
Most people with pneumonia can be completely cured. But it can be life-threatening, and you should take it seriously even if you’re young and fit.
What Causes Pneumonia?
Many germs can cause pneumonia. The most common are bacteria and viruses in the air we breathe. Bacterial pneumonia is the most common type in adults. Your body usually prevents these germs from infecting your lungs. But sometimes these germs can overpower your immune system, even if your health is generally good.
Pneumonia is classified according to the types of germs that cause it and where you got the infection.
Community-acquired pneumonia is the most common type of pneumonia. It occurs outside of hospitals or other health care facilities. It may be caused by:
Bacteria. The most common cause of bacterial pneumonia in the U.S. is Streptococcus pneumoniae. This type of pneumonia can occur on its own or after you've had a cold or the flu. It may affect one part (lobe) of the lung, a condition called lobar pneumonia.
Bacteria-like organisms. Mycoplasma pneumoniae also can cause pneumonia. It typically produces milder symptoms than do other types of pneumonia. Walking pneumonia is an informal name given to this type of pneumonia, which typically isn't severe enough to require bed rest.
Fungi. This type of pneumonia is most common in people with chronic health problems or weakened immune systems, and in people who have inhaled large doses of the organisms. The fungi that cause it can be found in soil or bird droppings and vary depending upon geographic location.
Viruses. Some of the viruses that cause colds and the flu can cause pneumonia. Viruses are the most common cause of pneumonia in children younger than 5 years. Viral pneumonia is usually mild. But in some cases it can become very serious.
Some people catch pneumonia during a hospital stay for another illness. Hospital-acquired pneumonia can be serious because the bacteria causing it may be more resistant to antibiotics and because the people who get it are already sick. People who are on breathing machines (ventilators), often used in intensive care units, are at higher risk of this type of pneumonia.
Health care-acquired pneumonia
Health care-acquired pneumonia is a bacterial infection that occurs in people who live in long-term care facilities or who receive care in outpatient clinics, including kidney dialysis centres. Like hospital-acquired pneumonia, health care-acquired pneumonia can be caused by bacteria that are more resistant to antibiotics.
Aspiration pneumonia occurs when you inhale food, drink, vomit or saliva into your lungs. Aspiration is more likely if something disturbs your normal gag reflex, such as a brain injury or swallowing problem, or excessive use of alcohol or drugs.
What are the Symptoms?
Symptoms of pneumonia may include:
Cough. You will likely cough up mucus (sputum) from your lungs. Mucus may be rusty or green or tinged with blood.
Fast breathing and feeling short of breath.
Shaking and "teeth-chattering" chills.
Chest pain that often feels worse when you cough or breathe in.
Feeling very tired or very weak.
Nausea and vomiting.
When you have mild symptoms, your doctor may call this "walking pneumonia."
Older adults may have different, fewer, or milder symptoms. They may not have a fever. Or they may have a cough but not bring up mucus. The main sign of pneumonia in older adults may be a change in how well they think. Confusion or delirium is common. Or, if they already have a lung disease, that disease may get worse.
Infants and newborns may not show specific symptoms of pneumonia. Instead, the baby or child may appear restless or lethargic. A baby or child with pneumonia may also have a fever or cough or vomit.
Symptoms caused by bacteria usually come on quickly, while, symptoms caused by viruses may come on slowly and often are not as obvious or as bad.
How is Pneumonia Diagnosed?
Your doctor will start by asking about your medical history and doing a physical exam, including listening to your lungs with a stethoscope to check for abnormal bubbling or crackling sounds that suggest pneumonia.
If pneumonia is suspected, your doctor may recommend the following tests:
Blood tests. Blood tests are used to confirm an infection and to try to identify the type of organism causing the infection. However, precise identification isn't always possible.
Chest X-ray. This helps your doctor diagnose pneumonia and determine the extent and location of the infection. However, it can't tell your doctor what kind of germ is causing the pneumonia.
Pulse oximetry. This measures the oxygen level in your blood. Pneumonia can prevent your lungs from moving enough oxygen into your bloodstream.
Sputum test. A sample of fluid from your lungs (sputum) is taken after a deep cough and analyzed to help pinpoint the cause of the infection.
Your doctor might order additional tests if you're older than age 65, are in the hospital, or have serious symptoms or health conditions. These may include:
CT scan. If your pneumonia isn't clearing as quickly as expected, your doctor may recommend a chest CT scan to obtain a more detailed image of your lungs.
Pleural fluid culture. A fluid sample is taken by putting a needle between your ribs from the pleural area and analyzed to help determine the type of infection.
How is it Treated?
Mild pneumonia can usually be treated at home. If pneumonia is caused by bacteria, your doctor will give you antibiotics. These almost always cure pneumonia caused by bacteria. Be sure to take the antibiotics exactly as instructed. Unless a healthcare professional tells you otherwise, you should always finish taking a prescribed course of antibiotics, even if you feel better.
If you stop taking an antibiotic part way through a course, the bacteria can become resistant to the antibiotic.
Pneumonia can make you feel very sick. But after you take antibiotics, you should start to feel much better, although your cough may last for some time. Call your doctor if you do not start to feel better after 2 to 3 days of antibiotics. Call your doctor right away if you feel worse.
There are things you can do to feel better during your treatment.
Get plenty of rest and sleep.
Drink lots of liquids.
Do not smoke.
If your cough keeps you awake at night, talk to your doctor about using cough medicine.
You may need to go to the hospital if you have bad symptoms, a weak immune system, or another serious illness.
Pneumonia caused by a virus usually is not treated with antibiotics. Sometimes, antibiotics may be used to prevent complications. But home treatment, such as rest and taking care of your cough, usually is all that is done.
What are Complications of Pneumonia?
There are a number of potential complications of pneumonia. The infection that causes pneumonia can spread to the bloodstream, causing sepsis. Sepsis is a serious condition that can result in lowering of blood pressure and failure of oxygen to reach the tissues of the body, resulting in the need for intensive care management. Another complication is the accumulation of fluid in the space between the lung tissue and the chest wall lining, known as a pleural effusion. The organisms responsible for the pneumonia may infect the fluid in a pleural effusion, known as an empyema. Pneumonia can also result in the formation of an abscess (collection of pus) within the lungs or airways.
Can Pneumonia be Prevented?
In many cases, pneumonia can be prevented. Experts recommend immunization for children and adults. Children get the pneumococcal vaccine as part of their routine shots. Two different types of pneumococcal vaccines are recommended for people ages 65 and older. If you smoke, or you have a long-term health problem, it's a good idea to get a pneumococcal vaccine. It may not keep you from getting pneumonia. But if you do get pneumonia, you probably won't be as sick. You can also get an influenza vaccine to prevent the flu, because sometimes people get pneumonia after having the flu.
Other prevention tips
In addition to vaccination, there are other things you can to avoid pneumonia:
If you smoke, try to quit. Smoking makes you more susceptible to respiratory infections, especially pneumonia.
Wash your hands regularly with soap and water.
Cover your coughs and sneezes, and dispose of used tissues promptly.
Maintain a healthy lifestyle to strengthen your immune system. Get enough rest, eat a healthy diet, and get regular exercise.
You can also lower your chances of getting pneumonia by staying away from people who have a cold, measles, or chickenpox. You may get pneumonia after you have one of these illnesses.
People with a weakened immune system should avoid close contact with a person with pneumonia until they start to get better.
Excessive and prolonged alcohol misuse also weakens your lungs' natural defences against infections, making you more vulnerable to pneumonia.
Is Pneumonia Contagious?
Most kinds of pneumonia are contagious. Both viral and bacterial pneumonia can spread to others through inhalation of airborne droplets from a sneeze or cough. Mycoplasma pneumoniae and tuberculosis are two types of bacterial pneumonia that are highly contagious.
But while you can become infected with fungal pneumonia from the environment, it doesn’t spread from person to person.
Who's at Risk of Pneumonia?
Some groups of people are at higher risk from pneumonia. If you’re in one of these groups, you should take extra care to reduce your chances of catching pneumonia.
People in these at risk groups include:
babies and young children from 2 years and below
people over age 65
people with long-term heart, lung and kidney diseases, or diabetes
people with cancer, especially those having chemotherapy
people who smoke or drink alcohol to excess
people on drugs that suppress the immune system, and those with HIV
People in hospital for other problems sometimes develop pneumonia while they’re there. This can be for several reasons including the use of mechanical ventilators, recent antibiotic use or because their resistance to infection has been weakened by other medical problems.
What is the Prognosis of Pneumonia?
Most people with pneumonia improve after three to five days of antibiotic treatment, but a mild cough and fatigue can last longer, up to a month. Patients who required treatment in a hospital may take longer to see improvement.
Pneumonia can also be fatal. The mortality (death) rate is up to 30% for patients with severe pneumonia who require treatment in an intensive-care unit. Overall, around 5%-10% of patients who are treated in a hospital setting die from the disease. Pneumonia is more likely to be fatal in the elderly or those with chronic medical conditions or a weakened immune system.