Pneumonia is an infection in one or both lungs. Bacteria and viruses typically cause pneumonia. Fungi can also cause some types of pneumonia.
Some people develop a serious case of pneumonia while in the hospital. But it’s more common to develop pneumonia outside a hospital setting. When this happens, doctors refer to it as community-acquired pneumonia (CAP).
CAP is the most common type of pneumonia people experience. Although it’s not usually as serious as hospital-acquired pneumonia (HAP), it can still have serious complications.
This article will look at CAP, how it compares with other types of pneumonia, and what you can do to protect yourself.
Types of pneumonia
- Community-acquired pneumonia (CAP): CAP refers to pneumonia you develop outside a hospital setting.
- Hospital-acquired pneumonia (HAP): Also called
nosocomial pneumonia, HAP occurs if you fall ill with pneumonia 48 hours or more after your admission to the hospital. HAP is usually more serious than CAP because it can involve bacteria that are resistant to antibiotics.
- Ventilator-associated pneumonia (VAP): A subgroup of people with HAP may develop VAP. It occurs in hospital patients who are receiving mechanical ventilation for respiratory failure.
Pneumonia has many causes.
- human rhinovirus (common cold)
- influenza virus (flu)
- Streptococcus pneumoniae
Other common causes include:
- the coronavirus SARS-CoV-2 (COVID-19)
- Haemophilus influenzae
- Legionella bacteria
- Mycoplasma pneumonia
- hard-to-detect bacteria, such as Chlamydia pneumoniae
So, how do humans come in contact with these germs?
Some of them, like Streptococcus pneumoniae, already live in your nose, sinuses, or mouth. They can eventually spread to your lungs, where they cause disease. It’s unclear why they invade the lungs.
You might also breathe in these germs if they are in the air around you. Certain activities or environments may increase your risk of coming in contact with them.
CAP and its complications are
- adults older than age 65
- people with existing health conditions
- people with a weakened immune system
- people who smoke
- people who are malnourished
Children younger than 5 years also have a
Certain conditions may increase your risk of developing CAP. According to a 2017 review of 29 studies, these include:
- chronic bronchitis or COPD
- diseases of the mouth, teeth, or gums
- conditions that cause impaired function
While the review was inconclusive on whether heart disease was a risk factor, other research from 2015 suggests it is.
Other conditions, such as
Researchers in the 2017 review also identified certain medications that may increase your risk:
- oral steroids
- proton pump inhibitors and H2 blockers (both used to treat gastric reflux)
According to the
- indoor air pollution from biomass fuels
- crowded homes
- secondhand smoke
living on or near a farm with livestock
- living near centers of industrial food animal production
According to 2015 research, people who smoke cigarettes also have a higher risk of CAP.
Zoonotic (animal) exposure
Exposure to certain animals that may carry the germs that cause CAP could put you at risk. According to research from
- birds, including poultry
- sick dogs
- cats in labor
The germs that cause CAP exist everywhere in the world. But some regions are more likely to have certain germs.
If you have symptoms of pneumonia, be sure to tell a doctor of any recent travel. It may help them make a diagnosis.
Pneumonia is a serious, sometimes fatal disease. The
- production of sputum
- difficulty breathing
- chest pain
- muscle aches
- irritability and restlessness (in infants)
- confusion (in older adults)
In some people, breathing issues and fluid buildup in the lungs may become severe. This may lead to respiratory failure and the need for oxygen therapy or mechanical ventilation.
If a doctor notices you have symptoms of CAP, they will likely perform or order the following:
- Medical history: A doctor will ask about your medical history to better understand how you may have become ill.
- Physical exam: A doctor will perform a physical exam to check for fever and lung sounds consistent with pneumonia.
- Chest X-ray: A chest X-ray can show any fluid buildup or inflammation in the lungs.
- CT scan: A doctor might use a CT scan to confirm a diagnosis or rule out other conditions. CT scans may be more effective at detecting pneumonia than chest X-rays, but they are more expensive and take longer.
- Complete blood count (CBC): A CBC can help doctors see whether your immune system is fighting the infection.
- Electrolyte panel: An electrolyte panel can check your electrolyte levels as well as your kidney and liver function.
- Blood, sputum, or urine tests: Blood and sputum cultures, as well as
urine antigen tests, may identify the exact cause of the infection, influencing treatment.
- Molecular testing: This is the standard way to test for viral pneumonia, such as cases caused by COVID-19.
Research from 2020has also shown that molecular tests, like polymerase chain reaction (PCR) tests, may also be better than cultures at detecting bacterial pneumonia.
A doctor will also consider other potential diagnoses. Some illnesses with symptoms similar to CAP include:
If you have CAP, your treatment plan will depend on your symptoms and the specific cause of your infection. A doctor will also consider how severe your symptoms are.
According to 2017 research,
It’s important to take antibiotics as prescribed. If you don’t follow the proper regimen, the bacteria could become antibiotic resistant.
If you have a more severe case of CAP, you may need to get treatment in a hospital. Healthcare professionals can provide a variety of intravenous (IV) antibiotic treatments based on your specific situation at a hospital.
But antibiotics do not work for cases of viral pneumonia. You may need to let the virus run its course. In some cases, you may be able to use antiviral medication. Examples include:
- remdesivir (Veklury) for COVID-19
- oseltamivir (Tamiflu) for influenza
- inhaled ribavirin for respiratory syncytial virus (RSV)
There are other actions you can take to manage symptoms of viral CAP:
- Take over-the-counter pain relievers, like acetaminophen or ibuprofen, to reduce fever.
- Drink plenty of fluids to stay hydrated.
- Get enough rest to allow your body to recover.
- Quit smoking if you regularly smoke.
If your symptoms are severe, you may need to go to the hospital. Additional treatments in the hospital may include:
- oxygen therapy
- intravenous (IV) fluids
- respiratory support with a ventilator
With CAP comes the risk of possible complications. These are more likely if doctors don’t make a timely diagnosis or if initial treatments don’t work.
- Pleural effusion: Pleural effusion is the buildup of fluid in your pleura, the space between your lungs and chest wall.
- Empyema: Empyema is the buildup of pus in the pleural space.
- Lung abscesses: An abscess is a pus-filled cavity that, in this case, forms in your lung.
- Sepsis: Sepsis is an extreme immune response to an infection.
- Acute respiratory distress syndrome (ARDS): ARDS occurs when the lungs become severely inflamed and fill with fluid, preventing oxygen from getting into the blood.
Complications like sepsis and ARDS can cause organ failure and death.
With rapid and appropriate treatment, many people fully recover from CAP without complications. Young people tend to recover fully more quickly.
If CAP is due to bacteria, you may start to feel better
If you have a mild case of CAP, full recovery is possible with rest, antibiotics or antivirals, and sleep.
More severe cases of CAP may require lengthy hospital stays to help keep you stable and aid recovery. For people admitted to intensive care, the death rate can be as high as
Taking precautions against illness, such as getting an annual flu shot, can reduce your risk of CAP. The
People over 65 can also consider getting the pneumococcal vaccine to prevent CAP. This is especially important if you have other health conditions or if you smoke.
You may need a booster shot if you received your vaccine before age 65, or if you have a weakened immune system.
Other everyday actions you can do to help prevent disease include the following:
- Wash your hands frequently, especially after using the bathroom or being in public.
- Cough into your elbow when you need to cough.
- Keep a physical distance from people who are ill.
- If you smoke or vape, consider quitting to reduce damage to your lungs. Such damage can make you more vulnerable to pneumonia infection.
Community-acquired pneumonia (CAP) is the most common type of pneumonia. The term refers to pneumonia that you contract outside of a hospital setting.
While many people recover from CAP with rest and antibiotic or antiviral treatment, it can be especially serious for older adults and people with existing health conditions.
Potential complications of CAP can be life threatening. But people in high risk groups can take precautions against severe disease, such as getting an annual flu shot.