Weekly blog - PCP (I guess it is PJP now)

Today we discussed a case of a heart transplant patient who developed late onset PCP (PJP)

Classically PCP presents with progressive dyspnea, usually initially with exertion then at rest, with dry hacking cough and fever. Classically the respiratory exam is relatively normal (sometimes there is a pleural rub) despite often remarkably abnormal chest x-ray. The classic x-ray, shown here, is of bilateral perihilar infiltrates.

LDH is usually elevated but can be normal in up to 10%. 

LDH can also be elevated in a number of other infections and malignancies.  

The degree of LDH elevation is associated with worse prognosis.

Exercise induced desaturation is "an old school classic finding" and one can do exercise oximetry on their patients to see this effect.

http://www.ncbi.nlm.nih.gov/pubmed/2658699

http://www.ncbi.nlm.nih.gov/pubmed/8128398

At our centre the diagnosis is confirmed by direct calciflor stain or silver stain for organisms in the BAL fluid or demonstration of the organism on transbronchial biopsy.  The yield of BAL is approximately 70% in solid organ transplant patients (see solid organ transplant below) which is increased with the biopsy.  Adding a test like beta-d-glucan (not currently available here) can increase sensitivity to 95% with some loss of specificity.

Monoclonal antibody staining  (not available here) for the organism can also increase yield 
http://jcm.asm.org/content/42/7/3333.full

Regarding prophylaxis and treatment of patients.

1) The guidelines for the prevention and management of PCP in solid organ transplant are available here.

http://onlinelibrary.wiley.com/doi/10.1111/ajt.12119/full

2) TMP/SMX is the standard of care for the majority of patients.  Corticosteroids are commonly used based on the HIV literature (NNT 9 without HAART and 23 with HAART) though the benefit is not as clear in transplant or other non-HIV therapies.

3) There is a significant delay to diagnosis in the transplant patient who presents late.
http://www.ncbi.nlm.nih.gov/pubmed/22548840

As KS suggested today -- when the patient is suspected of having PCP it is important to involve the pneumologists early to obtain a diagnostic sample while the patient is still well enough to undergo diagnostic testing

Sputum induction -- which is currently not done here for this -- has some literature in favor of its negative predictive value if done correctly (and in this case paired with DFA)
http://cid.oxfordjournals.org/content/37/10/1380.full

4) Regarding prophylaxis outside of transplant and hematologic cancers:
Not sure this link will work for all you mcgillians -- check this link!

From the reference -- estimated NNT to prevent one infection varies from:
11 in transplant and some hematologic malignancies
32 in granulomatious polyangiitis (on steroids and cyclophosphomide/other)
73 (or so) with brain tumors on therapy
110 in collagen vascular disease (other than polyangiitis), prolonged prednisone (definition varies -- some say greater than 40mg/day for 3 months, others more restrictive 20mg/day >2 months)
1100 in rheumatoid arthritis