*Pneumonia Caused by Pneumocystis jiroveci Infection (Pneumocystosis)

Chapter: Pneumonia Caused by Pneumocystis jiroveci Infection (Pneumocystosis)
McMaster Section Editor(s): Mark Loeb
Section Editor(s) in Interna Szczeklika: Ewa Niżankowska-Mogilnicka, Filip Mejza
McMaster Author(s): Mark Loeb
Author(s) in Interna Szczeklika: Jan Kuś, Miłosz Jankowski
Additional Information

Etiology and PathogenesisTop

Pneumonia caused by Pneumocystis jiroveci (previously Pneumocystis carinii) (PCP) develops in patients with impaired cell-mediated immunity (most commonly in patients with AIDS). The incubation period lasts several weeks.

Clinical presentation: The most common manifestations include fever, dry cough, and dyspnea. In human immunodeficiency virus-positive patients, the progression of symptoms may be very slow. White blood cell counts are normal, while lactate dehydrogenase levels are elevated. In patients with early disease, chest radiographs may frequently be normal; later they reveal bilateral, symmetrical, ground-glass opacities. Carbon dioxide diffusing capacity of the lungs (DLCO) is decreased.

DiagnosisTop

Detection of trophozoites or cysts of Pneumocystis jiroveci in sputum (sensitivity, 60%), induced sputum, or bronchoalveolar lavage (sensitivity, 95%). In rare cases, lung biopsy (transbronchial or surgical) is necessary.

TreatmentTop

Sulfamethoxazole/trimethoprim (trimethoprim 15 mg to 20 mg/kg/day) IV or po in 3 or 4 divided doses for 3 weeks. In patients with a contraindication to sulfamethoxazole/trimethoprim with severe PCP, use intravenous pentamidine (4 mg/kg/day IV). For treatment of mild to moderate PCP in patients who are intolerant of sulfamethoxazole/trimethoprim, alternative regimens include clindamycin (600 mg/day po in divided doses administered every 8 hours in combination with primaquine 30 mg/day po), atovaquone 750 mg po bid, trimethoprim (5 mg/kg po tid) plus dapsone. In patients with partial pressure of oxygen in arterial blood (PaO2) <70 mm Hg on room air, an alveolar-arterial (A-a) oxygen gradient ≥35 mm Hg, and/or evidence of hypoxemia (eg, room air oxygen saturation <92%), we suggest a glucocorticoid (prednisone 40 mg po every 12 hours for 5 days followed by 40 mg/day for 6 days and 20 mg/day for the subsequent 10 days).Evidence 1Strong recommendation (benefits clearly outweigh downsides; right action for all or almost all patients). High Quality of Evidence (high confidence that we know true effects of the intervention). Ewald H, Raatz H, Boscacci R, Furrer H, Bucher HC, Briel M. Adjunctive corticosteroids for Pneumocystis jiroveci pneumonia in patients with HIV infection. Cochrane Database Syst Rev. 2015 Apr 2;(4):CD006150. doi: 10.1002/14651858.CD006150.pub2. Review. PubMed PMID: 25835432.

PreventionTop

In immunosuppressed patients and patients with human immunodeficiency virus infection who have completed treatment, use sulfamethoxazole/trimethoprim (trimethoprim 80-160 mg po daily or 160 mg po 3 times/week).

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