What is Community-Acquired Pneumonia?

Community-acquired pneumonia is a very common type of lung infection that can be caused by many different bacteria, viruses, and fungi. By definition, the infection is caught somewhere outside of hospitals and other health-care settings. Cases of community-acquired pneumonia are generally less likely to cause major outbreaks among a population than infections acquired at hospitals, where many people are exposed to contagious patients. Pneumonia can cause a wet cough, fever, fatigue, and breathing difficulties that usually get better in a couple weeks with medications and rest. A very serious infection may require hospitalization and critical care to prevent life-threatening problems.

Pneumonia can affect people of all ages, but infants, young children, and the elderly are at the highest risk. The main risk factors for adults include smoking, drinking in excess, and having a weakened immune system due to chronic illness. The bacterium Streptococcus pneumoniae is responsible for most cases of community-acquired pneumonia worldwide. Respiratory syncytial virus and adenovirus are common sources of viral illness, especially in children. Several other bacterial, viral, fungal, and parasitic infestations can lead to lung infection as well.

The symptoms of community-acquired pneumonia can vary, depending on the nature of the infection and a person's age and health. Most people first experience a dry cough that becomes productive over several hours or days. Headaches, muscle pains, fever, and chills are common. A person may also sweat excessively and have trouble taking deep breaths. In severe cases, breathing and heart rate can slow to dangerous levels and a person may pass out due to lack of oxygen. Without treatment, there is also a risk of pathogens spreading from the lungs to the bloodstream and causing a systemic infection.

A person who has signs of pneumonia should be evaluated by a doctor as soon as possible. A physician can listen to breathing with a stethoscope and ask questions about symptoms to make a basic diagnosis. Blood and mucus samples are usually collected and tested in a laboratory to determine what type of bacteria, virus, or other pathogen is responsible for infection. If a patient has significant breathing difficulties, x-rays of the lungs may be taken to gauge the seriousness of lung damage.

Mild bacterial infections tend to respond well to prescription antibiotics. Patients are generally instructed to take their medications daily for about three to four weeks and schedule follow-up visits to make sure they are fully cured. Viral pneumonia is difficult to treat with drugs, and people simply need to rest, stay hydrated, and wait for infection to run its two- to four-week course. If breathing problems and other symptoms become debilitating, oxygen therapy, intravenous drugs, and other treatment measures in a hospital are needed. Most otherwise healthy children and adults are able to recover from community-acquired pneumonia when quality health care is available.