Pneumocystis jirovecii Pneumonia Identification in an Immunocompromised Patient

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A 34-year-old man presented to his physician complaining of cough, weight loss, night sweats, fever and shortness of breath. He had a past medical history of Non-Hodgkin Lymphoma and neuropathy. On presentation the patient was tachycardic and hypotensive. A chest x-ray and bronchoscopy was ordered.

Lab Testing

Based on the abnormal chest x-ray and symptoms, several microbiology tests were ordered including bacterial, viral, mycobacteria, legionella and fungal cultures, and a legionella urinary antigen. Gram-stain and acid-fast stains were both negative however Geimsa staining showed the presence of 1-5 µm trophozoites and cyst-like structures. Gomori methenamine silver and calcofluor white stains were performed to confirm the presence of Pneumocystis jirovecii pneumonia.

Cause of Symptoms

The differential diagnosis in this patient consists of a variety of infectious causes upon presentation, the chest x-ray was abnormal and the patient presented with a cough and was febrile. Transmission of Pneumocystis jirovecii is airborne via person-to-person. There are 3 life cycle stages of the organism: trophic (trophozoite), sporozoite (pre-cyst form) and ascus (cyst form). After inhalation of the pathogen, the trophic form of the organism adheres to the epithelium of the lung. Organisms replicate in the lung spaces extracellularly. Infection with Pneumocystis jirovecii impairs oxygen diffusion capacity and causes hypoxia. Pneumocystis jirovecii used to be classified as a protozoan, but is now considered a fungus. Pneumocystis jirovecii used to be called Pneumocystis carinii.


Treatment of Pneumocystis jirovecii pneumonia typically consists of Trimethoprim-sulfamethoxazole (TMP-SMX).

Contact Information

Nicole Jackson,