Pneumocystis jirovecii pneumonia in a patient with HIV infection: complex diagnosis using Giemsa-stained bronchoalveolar lavage fluid.

A 54-year-old Brazilian man presented to the emergency department with cough, chest pain, high fever, and dyspnea. He had no history of sexually transmitted infections. A thoracic computed tomography scan showed ground-glass opacification areas and mediastinal lymphadenopathy. Laboratory tests revealed the following abnormalities: absolute monocyte count,80 cells/mm3; partial pressure of oxygen, 55.3 mmHg; and C-reactive protein,304.3 mg/L. Blood tests for cytomegalovirus, Chlamydia pneumoniae, Legionella pneumophila, and Mycoplasma pneumoniae and a sputum analysis for Mycobacterium tuberculosis were negative. Microscopic examination of Giemsa-stained bronchoalveolar lavage fluid (BALF) showed cysts of the atypical fungus Pneumocystis jirovecii (Figure 1), the etiological agent of pneumocystis pneumonia (PCP). Additional investigations revealed human immunodeficiency virus (HIV) infection, low CD4+T-cell count (128 cells/mm3), and increased lactate dehydrogenase levels. Antiretroviral therapy (ART) and trimethoprim/sulfamethoxazole (14 days) treatment were established. The patient was discharged 30 days post-admission.

FIGURE 1:

Giemsa staining (original magnification, ×1000) of bronchoalveolar fluid showing cyst forms of Pneumocystis jirovecii (black arrow).

PCP is a life-threatening infection that is often observed in immunocompromised individuals. Although the incidence has decreased among HIV-infected individuals due to the widespread use of ART and prophylaxis, PCP remains the most prevalent opportunistic infection among HIV-infected patients worldwide and persists as the main acquired immunodeficiency syndrome-defining infection .

Due to non-specific signs and symptoms, and because P. jirovecii cannot be cultured in artificial media, the diagnosis of PCP is challenging. Methods involving DNA detection and serological biomarkers are available, but the microscopic observation of P. jirovecii in BALF is still the gold standard for PCP diagnosis , .