Pneumocysitis jirovecii pneumonia was previosuly named Pneumocystis carinii pneumonia. Some of the debate regarding the name change can be found here and in the associated references. Previously classified as a protozoa, but molecular studies have shown it to likely be a FUNGUS.
Generally occurs in HIV+ patients with a CD4 count below 200 cells/mm3. Can also occur in other immunosuppressed hosts.
PRESENTATION
Subacute onset of (exertional) dyspnea, dry cough +/- "low-grade" fever.
Physical Exam shows tachypnea, tachycardia and normal lung auscultation in 50% (the remainder having crackles etc.).
CXR - classically bilateral, perihilar interstitial infiltrates, but can show almost anything (or nothing). However, pleural effusions and/or lymphadenopathy is very rare.
DIAGNOSIS
In addition to the clinical presentation, microscopic examination of (induced) sputum, BAL fluid or tissue can be performed. PJP cannot be readily cultured (be sure to specify you want sputum tested for PJP if it is in your Ddx), it can be seen with methenamine silver or immunofluorescence stains.
Laboratory data is generally not very informative. LDH is elevated in 90%, but this is very non-specific.
TREATMENT
TMP-SMX - high dose (see reference) x 21 days. Alternatives included inhaled pentamidine and atovaquone. Remember to start prophylaxis after finishing treatment!
Patients with PCP may worsen after two to three days of therapy, possibly from inflammation in response to dying organisms.
Corticosteroids are of benefit in patients who are hypoxic at presentation (PaO2 on room air less than 70mmhg or oxygen saturation <90%)
The benefit of steroids in PCP was shown in a study conducted in Toronto in 1987.
A NEJM review article can be found here
Thanks to prior CMRs for some of the above.
As discussed at noon rounds: Nystatin was isolated from Streptomyces noursei by Elizabeth Lee Hazen and Rachel Fuller Brown. The soil sample where they discovered nystatin was from the garden of Hazen's friends, Walter B. Nourses, therefore the strain was called noursei. It contained a substance that they first named fungicidin, a name that had already been used for another substance. They then renamed the substance nystatin in honor of the New York State Public Health Department, where they worked.
