Pneumocystis pneumonia Questions and Answers
Pneumocystis pneumonia (PCP)
is a form of pneumonia, caused by the yeast-like fungus Pneumocystis jirovecii.[1]
Pneumocystis pneumonia is not commonly found in the lungs of healthy people, but, being a source of opportunistic infection, it can cause...
Pneumocystis pneumonia Questions
and Answers
Pneumocystis pneumonia (PCP) - answer is a form of pneumonia, caused by the
yeast-like fungus Pneumocystis jirovecii.[1]
Pneumocystis pneumonia is not commonly found in the lungs of healthy people, but,
being a source of opportunistic infection, it can cause a lung infection in people with a
weak immune system. Pneumocystis pneumonia is especially seen in people with
cancer undergoing chemotherapy, HIV/AIDS, and the use of medications that suppress
the immune system
Signs and symptoms - answer Signs and symptoms of PCP include fever, non-
productive cough (because sputum is too viscous to become productive), shortness of
breath (especially on exertion), weight loss, and night sweats. There is usually not a
large amount of sputum with PCP unless the patient has an additional bacterial
infection. The fungus can invade other visceral organs (such as the liver, spleen, and
kidney), but only in a minority of cases.
Pneumothorax is a well-known complication of PCP.[2] An acute history of chest pain
with breathlessness and diminished breath sounds is typical of pneumothorax.[
Disease course - answer The risk of PCP increases when CD4 positive T-cell levels
are less than 200 cells/μL. In these immunosuppressed individuals the manifestations of
the infection are highly variable.[3] The disease attacks the interstitial, fibrous tissue of
the lungs, with marked thickening of the alveolar septa and alveoli, leading to significant
hypoxia which can be fatal if not treated aggressively. In this situation LDH levels
increase and gas exchange is compromised. Oxygen is less able to diffuse into the
blood, leading to hypoxia. Hypoxia, along with high arterial carbon dioxide (CO2) levels,
stimulates hyper-ventilatory effort, thereby causing dyspnea (breathlessness).
Diagnosis - answer The diagnosis can be confirmed by the characteristic
appearance of the chest x-ray, which shows widespread pulmonary infiltrates, and an
arterial oxygen level (PaO2) that is strikingly lower than would be expected from
symptoms. Gallium 67 scans are also useful in the diagnosis. They are abnormal in
approximately 90% of cases and are often positive before the chest x-ray becomes
abnormal. The diagnosis can be definitively confirmed by histological identification of
the causative organism in sputum or bronchio-alveolar lavage (lung rinse). Staining with
toluidine blue, silver stain, periodic-acid schiff stain, or an immunofluorescence assay
will show the characteristic cysts.[4] The cysts resemble crushed ping-pong balls and
are present in aggregates of 2 to 8 (and not to be confused with Histoplasma or
Cryptococcus, which typically do not form aggregates of spores or cells). A lung biopsy
would show thickened alveolar septa with fluffy eosinophilic exudate in the alveoli. Both
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