NORD gratefully acknowledges Stephanie Phan, NORD Editorial Intern from the Keck Graduate Institute, and Charles F. Thomas, Jr., MD, Associate Professor of Medicine, Division of Pulmonary & Critical Care Medicine, Mayo Clinic, for assistance in the preparation of this report.
Pneumocystis pneumonia is a type of infection of the lungs (pneumonia) in people with a weak immune system. It is caused by a yeast-like fungus called Pneumocystis jirovecii (PJP). People with a healthy immune system don't usually get infected with PCP. It becomes a problem only for people with a weak immune system that allows the fungus to cause infection. The immune system can be weakened by cancer, HIV infection or AIDS, high dose corticosteroids, or from medicine taken after having a bone marrow or organ transplant. It is the most common opportunistic infection found in HIV infected people and may cause mild symptoms. However, in individuals who do not have HIV infection it is typically characterized by severe respiratory failure coupled with fever and dry cough much like most pneumonias. Nearly all individual with PJP will have either low levels of oxygen in their blood (hypoxemia) at rest or with exertion, or an increase in the alveolar-arterial oxygen tension gradient which makes it difficult for an individual to breathe.
Pneumocystis pneumonia is characterized by a gradual onset with shortness of breath and/or difficulty breathing. This disorder may be accompanied with fevers, night sweats, weight loss and dry cough. Dry cough is one distinction from typical pneumonia because spit (sputum) is too thick to become productive, therefore productive cough is not as common in PJP. Uncommonly, the PJP fungus can spread to other body organs such as the liver, kidney and spleen as the disease progresses.
Pneumocystis pneumonia is caused by the yeast-like fungus Pneumocystis jirovecii that most commonly presents as an opportunistic infection in HIV infected patients, but may present in a variety of people with weak immune systems. Most individuals infected are unaware of their HIV infection at the time of presentation and thus are not receiving PJP prophylaxis and are more prone to acquire PJP.
PJP is a frequent AIDS-defining diagnosis in the United States and in Europe. Pneumocystis pneumonia is commonly seen in HIV infected people with a CD4 count of less than 200 cells/mm3. People receiving high doses of glucocorticoids or other immunosuppressive drugs after an organ transplant or to treat cancer are at risk for PJP. People with other inflammatory conditions such as granulomatosis with polyangiitis (Wegener’s), polymyositis or dermatomyositis can also have an increased risk of acquiring PJP.
The diagnosis of Pneumocystis pneumonia requires multiple tests such as a chest X-ray and a sample of sputum collected by a procedure called bronchoalveolar lavage to differentiate PJP between from other causes of pneumonia. To further confirm PJP, a test to amplify trace amounts of DNA (polymerase chain reaction or PCR) is used and a blood test to detect β-D-glucan is used.
PJP infection can be serious, but many people can be treated at home with antibiotics such as Bactrim (trimethoprim and sulfamethoxazole). There are also different alternative therapies such as atovaquone, dapsone, primaquine w/ clindamycin, and pentamidine. Oxygen therapy may be needed to help get more oxygen into your lungs and bloodstream.
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Accessed April 24, 2018.
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