Pneumocystis jiroveci pneumonia (PCP)
- P jiroveci, previously known as P carinii is a fungal organism
- AIDS-defining infections
- Incidence of PCP is
- 0.5% in HIV-infected individuals with a CD4 count of >200, 8% in those with a CD4 count < 200 cells/µL
- X3 more prevalent in Caucasians
- PCP probable airborne transmission
- Sporozoites differentiate into trophozoites in lung tissue
- Exaggerated immune response causes lung damage and reduced alveolar gas exchange
Clinical
- Fever, SOB and dry cough
- Occasional chest pain and wt loss
- May be asymptomatic
- Exam = tachypnoea, crackles (+/- wheeze)
- Microscopic confirmation require for Dx
Investigations
- Saline induced sputum +/- BAL (sensitivity up to 98%)
- If ETT, aspirated (sensitivity 90%)
- Possible role PCR
- CXR - bilat perihilar interstitial infiltrates (+ PTX in ~ 30%)
- CXR findings resolve in 2-4 weeks with treatment
- Chest CT if doubt persists
Treatment
- Trimethoprim-sulfamethoxazole for 21 days.
- 2nd line - parenteral pentamidine, atovaquone, dapsone-trimethoprim, or clindamycin-primaquine
- Empiric treatment for PCP is discouraged
- Steroids if pulmonary infiltrates / hypoxia
