Pneumocystis pneumonia (PCP), caused by Pneumocystis jirovecii (P. jirovecii), is a fungal opportunistic infection seen in poorly controlled Human Immunodeficiency Virus (HIV) and is considered an Acquired Immune Deficiency Syndrome (AIDS) defining illness. It is also found in other immunocompromised states, such as hyper IgM syndrome and in patients on immunosuppressive therapy. In the HIV+ population, a CD4+ T-lymphocyte count (CD4 count) less than 200 cells/mm3 is associated with an increased risk of PCP. Combination antiretroviral therapy in conjunction with PCP prophylaxis has significantly decreased the prevalence of this opportunistic infection. In the United States HIV-infected population, PCP prevalence has decreased from 29.9 per 1000 person years between 1994 to 1997 to 3.9 per 1000 person years between 2003 to 2007.1 At the onset of the HIV/AIDS epidemic, PCP occurred in 70% to 80% of patients with AIDS.2 PCP should be highly suspected in HIV+ patients with bilateral symmetrical interstitial infiltrates on chest radiography, hypoxemia, and a CD4 count less than 200 cells/mm3 in addition to infectious respiratory symptoms such as cough, fever, and dyspnea. For definitive diagnosis, histopathologic or cytopathologic organism identification is required, most commonly via bronchoalveolar lavage or tissue biopsy. In addition to pneumonia, P. jirovecii can invade the liver, spleen, and kidneys. It has also been associated with pneumothorax. Less commonly, it has been associated with pneumomediastinum without pneumothorax.

Case Presentation:

This is a 39-year-old man with a twenty-year history of HIV who presented with one month of worsening shortness of breath, dry cough, and dysphagia. At admission, the patient had a CD4 count of 52 cells/mm3, a viral load of 456,074 copies/mL, and a history of non-adherence to HIV treatment. Prior to admission, the patient was not taking his prescribed antiretroviral therapy or PCP prophylaxis. These were re-initiated at the time of admission. In the hospital, the patient had progressive hypoxia that eventually required high flow oxygen supplementation at 35 L/minute and 100% FiO2. Initial chest x-ray showed diffuse bilateral infiltrates.