inpatient / Infectious disease

Pneumocystis Jirovecci Pneumonia (PJP/PCP)

Last Updated: 1/23/2023


-- ABCs: 
if in resp distress, intubate as needed; get ABG to assess severity of disease
-- Chart Check: immunocompromising meds (if pred - dose and how long they've been taking), h/o transplant, HIV, malignancy
-- HPI Intake: h/o HIV, transplant, steroid use, dyspnea, fevers, non-productive cough
-- Can't Miss: severe PJP, disseminated fungal infection, new dx HIV
-- Admission Orders: continuous pulse ox, LDH, BDG, CT chest
-- Initial Treatment to Consider: IV bactrim in severely hypoxic immunocompromised patients with characteristic GGOs; add steroids if PaO2 <70 on RA

-- History: *** HIV, CD4, steroid, transplant, heme malignancy
-- Clinical/Exam: *** hypoxemia, dyspnea, fever, non-productive cough
-- Data: *** CXR, CT Chest, BDG, LDH
-- Etiology/DDx: *** viral, atypical PNA, aspergillus, candida, endemic mycoses, ARDS, ILD/hypersensitivity

The patient's HPI is notable for ***. Exam showed ***. Labwork and data were notable for ***. Taken together, the patient's presentation is most concerning for ***, with a differential including ***.

-- Labs: f/u 1,3-BDG, LDH, daily CBC, CMP
-- ABG to determine severity and need for steroids
-- Send CD4 and viral load if patient with HIV
-- f/u CT Chest 
-- Consider BAL with PJP PCR (95% sensitivity and specificity) and galactomannan, histo, crytpo, blasto Ag if dx uncertain

--O2: currently *** with goal SpO2 >92%
-- Abx: *** bactrim IV 5mg/kg q6 for 21 days, switch to PO with clinical improvement; trimethoprim and dapsone is alternative for sulfa allergy; consider covering empirically for other invasive fungal infections with voriconazole if acutely ill and still being worked up (covers candida, crypto, endemic fungi, aspergillus)
-- PPx:  Bactrim DS daily if on pred 20mg or more for greater than 2-4 weeks, stem cell transplant, leukemia; SS daily okay too if DS not tolerable
-- Steroids: *** pred 40mg BID if hpoxemic with PaO2 <70 on RA or SaO2 <92%

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If You Remember Nothing Else

PJP is common enough to keep on the differential for immunocompromised patients, and is often diagnosed late due to similarities with atypical pneumonia. Pred of 20mg daily for ~4 weeks is enough to put a patient at risk, though is usually seen in those who are more profoundly immunocompromised. It is very unlikely that a patient will have an iatrogenic infection with PJP while in the hospital. CT chest has a high NPV - if there are no characterisitc GGOs, its unlikely PJP. BDG is sensitive but not specific, and should raise concern for fungal infection in general. If PJP is confirmed or highly suspected (severe hypoxia and GGOs in HIV patient with CD4 <200), Bactrim is first line, followed by TMP+dapsone.

Clinical Pearls

  • Pneumocystis carinii now refers only to the Pneumocystis that infects rats, and P. jirovecii refers to the distinct species that infects humans. However, the abbreviation PCP is still used to designate Pneumocystis pneumonia; Antonio Carini, who initially identified the subspecies P. carinii in rats and incorrectly described it as the same pathogen found in humans because of its similarities. However, the correct human pathogen was later identified in children and pigs by Otto Jirovec, explaining the name change from P. carinii to P. jirovecii. Despite this change in terminology for the organism, the most common abbreviation for the type of pneumonia associated with it remains PCP
  • PCP was the most common cause of death in HIV patients prior to HAART 
  • CD4 <200 or steroids of ~ pred 20mg/day for 2-4 weeks is usually enough to be at risk for PJP (tacrolimus not as big a risk) - someone chronically on steroids can be at risk up to 3-6 months after being tapered
  • Within 6 months of CD4 falling below 200, 8% of patients develop PCP 
  • Risk factors for invasive fungal infections include heme malignancy, stem cell transplant; also solid organ transplant patients and those on biologics, those less commonly
  • To get PCP, you need to be immunocompromised and you are very unlikely to get it iatrogenically while admitted to the hospital 
  • PCP is often misdiagnosed as atypical pneumonia based on similar CXR findings and dry cough
  • Those with HIV usually have PJP disease that develops slowly and presents less severely, those without HIV usually have a more severe, acute presentation 
  • 1,3-BDG is a cell wall polysaccharide unique to fungi - seen in PJP, aspergillus, candida, Histoplasma, coccicdioides, rhizopus; notable exceptions include Blastomyces, cryptococcus
  • 1,3-BDG can be false pos if treated with IVIG, albumin, on dialysis, drugs like cefepime
  • LDH >500 and 1,3-BDG (77% sens, 86% spec) is sensitive but not specific or PJP 
  • CXR - will often show diffuse bilateral reticular infiltrates on imaging, but is normal in 30%
  • CT Chest will show characteristic faint GGOs, and sometimes cystic spaces; CT without GGOs has high NPV; PJP will rarely show lung cavities or pleural effusions - if those are present, consider other ddx
  • PJP can cause PTX if it leads to a more cystic pathology
  • Fluconazole does not cover endemic fungi and aspergillus, thus voriconazole or posaconazole is preferred for empiric coverage for possible disseminated fungal infection, especially in immunocompromised patients

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