One-Pager by @CPSolvers 📝
Pearls ⚪
Importance of Early Diagnosis
- HIV ⊖ vs. ⊕: compared to HIV-⊕ patients, HIV-⊖ patients who are immunocompromised for other reasons (e.g. TNF-alpha inhibitor use, prolonged steroids without PJP prophylaxis) carry a substantially higher risk of more severe pneumonia & increased mortality, with some studies citing mortality up to ~50%. Unfortunately, due to widespread cognitive bias that PJP is only a disease of AIDS, diagnosis & treatment are often delayed
Making the Diagnosis
- To make a DEFINITIVE Dx, some sort of microbiologic test must return positive (e.g. BAL vs. induced sputum PCR, DFA, or silver stain)
- To make a PRESUMPTIVE Dx, compatible chest imaging can be paired w/ a compelling serologic marker
Serologic Markers
- LDH, test characteristics: in HIV-⊖ patients, a LDH cut-off of ~380 U/L has a ~85% sensitivity & ~80% specificity in distinguishing proven PJP from controls
- Beta-D Glucan (BDG), test characteristics: in HIV-⊖ patients, a BDG cut-off of ~285 pg/mL has a ~90% sensitivity & ~95% specificity in distinguishing proven PJP from controls, & a cut-off of 110 pg/mL has a 88% sensitivity & 86% specificity for probable PJP. (Taken together, a cut-off of ~144 pg/mL has a sensitivity of ~90% & specificity of ~86% for both probable/proven PJP.)
- Beta-D Glucan (BDG), mean elevation: ~980-1,200 pg/mL
BDG Limitations
- Notable false positives include IV penicillin formulations (e.g. Zosyn), IVIg & other blood products (e.g. albumin), hemodialysis via cellulose membranes, & indwelling gauze
References 📚
