Welcome back to the tasty morsels of critical care podcast.
Pneumocystis Jriovecii Pneumonia, the infection formerly known as Pneumocystis Carinii Pneumonia
The official change in name from Carinii to Jirovecii was in the late 1990s to emphasise the distinct organism that infected humans and named after a chap called Otto Jirovec. it seems that there was just one “i” when the name first changed as Pneumocystis was at that time thought to be a protozoa. once conclusively shown to be a fungal infection heavyweights from the International Code of Nomenclature for algae, fungi, and plants (the ICNafp) weighed in and it became officially Jirovecii with “i”s at the end. All of this is from what I picked up from Wikipedia on a Sunday afternoon. The main use of this information will come when some smug consultant corrects one of the team when they say PCP instead of PJP and then to rescuse the juniors from their shame you can bust out the ICNafp declaration on the two “i”s and arise victorious over said smug consultant. At least that’s the way it went in my head anyhow.
Back to some actual medicine then.
You can split pneumocystis into two contexts clinically
- the poorly controlled or first presentation HIV patient
- these guys tend to have a fairly slow and insidious presentation of breathlessness over weeks but not severe enough to present to hospital
- when they do present expect hypoxia and probable CXR changes
- a small number will have PTX in this group
- probably have a higher burden or organism overall
- the immunosuppressed patient
- this could be steroids, solid organ transplant or a haem malignancy
- often more like a typical acute respiratory infection with fever, cough, SOB
Both groups will have the now infamous ground glass appearances on imaging.
Diagnosis can be tricky and from an ICU perspective they’re probably sick enough to justify empiric treatment based on context without waiting for all the results. Usual stuff like CXR, CT and labs yadda yadda yadda… Commonly we order BDG (a common component of fungal organisms) but it’s not clear how good a test it is to rule in or rule out. LDH, while commonly ordered is even less useful.
A BAL is probably going to be needed and on this you have a few options
- silver staining
- immunofluresence (which is probably most sensitive)
- PCR (which is good but can’t distinguish carriage from infection. however if -ve then you’re probably in the clear)
There’s a reasonable guideline from the ATS in 2019 which covers this and is worth a read
Management wise the key spinal level reflex when this is considered is cotrimoxazole. This should be at high dose which you should check in a book or with a pharmacist. While pneumocystis is fungal we can’t use our usual anti-fungals like echinocandins or azoles (the caspofungins and fluconazoles) as pneumocystis has cholesterol in its walls and not ergosterol.
For those intolerant of cotrimoxazole some words to consider mentioning in an exam setting would be clindamycin, primaquin and pentamidine but in reality there is expertise and pubmed to help with that question.
If they’re in ICU then the cotrimoxazole should be given with a chaser of steroids as this has a mortality altering effect.
Fishman JA, Gans H; AST Infectious Diseases Community of Practice. Pneumocystis jiroveci in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice. Clin Transplant. 2019 Sep;33(9):e13587. doi: 10.1111/ctr.13587. Epub 2019 Jul 1. PMID: 31077616.