-Year-Old Homeless Man Presents To The Emergency Departmen

A 39 Year Old Homeless Man Presents To The Emergency Department Forco

A 39-year-old homeless man presents to the emergency department for cough and fever. He reports that his illness has been worsening over the past 2 weeks, initially experiencing dyspnea on exertion, now at rest. He lives in a homeless shelter and often sleeps on the streets, with a history of IV drug use, primarily heroin, on and off for many years. He denies prior medical history, but reviews of systems reveal fatigue, weight loss, and diarrhea. On examination, he appears thin, disheveled, and older than his age. His vital signs include a temperature of 100.5°F (38.0°C), blood pressure of 100/50 mm Hg, pulse of 105 beats/min, respiratory rate of 24 breaths/min, and an initial oxygen saturation of 89% on room air, improving to 94% on 4 L nasal cannula. Clinical findings include dry mucous membranes, tachycardia with a regular rhythm, a benign abdomen, and wasted extremities. Pulmonary examination shows tachypnea and bilateral fine crackles, with no cyanosis. Chest X-ray reveals diffuse bilateral interstitial infiltrates that appear as ground-glass opacities.

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The patient's presentation of progressive respiratory symptoms, constitutional signs such as weight loss and diarrhea, and characteristic radiographic findings suggest a diagnosis of Pneumocystis jirovecii pneumonia (PCP). This opportunistic infection predominantly afflicts immunocompromised individuals, particularly those with HIV/AIDS, making it the most likely cause of his current pulmonary complaints.

Most Likely Cause of Pulmonary Complaints

Pneumocystis jirovecii is a fungus that causes pneumonia primarily in individuals with compromised immune systems. The classic presentation includes subacute onset of dyspnea, non-productive cough, low-grade fever, and bilateral ground-glass opacities on chest imaging. The ground-glass appearance on the chest X-ray results frominterstitial infiltrates caused by alveolar and interstitial inflammation, typical of PCP. The patient's clinical features, such as hypoxia with oxygen desaturation, tachypnea, and bilateral crackles, further suggest PCP.

Underlying Illness Most Likely Present

The most probable underlying illness contributing to this presentation is HIV infection leading to AIDS. The patient's homelessness, IV drug use, weight loss, diarrhea, and advanced pulmonary findings are consistent with advanced immunodeficiency. Importantly, the wasting appearance and systemic signs point to a chronic illness, most consistent with AIDS-related immunosuppression. PCP is one of the most common opportunistic infections in AIDS patients, typically occurring when CD4 T-cell counts fall below 200 cells/mm³.

Testing and Initial Management

Immediate diagnostic steps should include laboratory and microbiological investigations. An important initial test is an HIV test, including both antibody and antigen testing, to confirm the diagnosis. A CD4 count is essential to assess immune status and guide prophylaxis and treatment. A sputum sample or induced bronchoalveolar lavage (BAL) should be obtained for microscopy with special stains (e.g., Gomori methenamine silver or immunofluorescence) sensitive for Pneumocystis organisms.

Chest high-resolution computed tomography (HRCT) can provide detailed evaluation, although it may not be immediately necessary if initial imaging and clinical suspicion are high. Laboratory tests including arterial blood gases may reveal hypoxemia with increased alveolar-arterial (A–a) gradient, characteristic of PCP.

Empiric treatment should be initiated promptly based on clinical suspicion, given the severity of presentation. First-line therapy includes high-dose trimethoprim-sulfamethoxazole (TMP-SMX), administered orally or intravenously, depending on severity. Adjunctive corticosteroids are indicated in moderate to severe hypoxemia (PaO₂

Furthermore, supportive care includes oxygen supplementation to maintain adequate oxygenation, hydration, and nutritional support. Given his immunocompromised state, prophylaxis for other opportunistic infections (such as toxoplasmosis and Mycobacterium avium complex) should be considered once stabilized, along with initiation of antiretroviral therapy.

Additional Considerations

Comprehensive care involves diagnosing and managing co-infections common in HIV-positive individuals, including tuberculosis, viral hepatitis, and bacterial infections. Testing for other infections should be conducted accordingly. The role of prophylactic antibiotics, such as prophylactic TMP-SMX to prevent PCP in at-risk patients (CD4

This case underscores the importance of recognizing opportunistic infections as initial manifestations of undiagnosed HIV infection. Timely diagnosis and aggressive therapy can significantly reduce morbidity and mortality associated with AIDS-related pneumonia.

References

• Freeman, J., & Riedel, D. (2018). Pneumocystis jirovecii pneumonia: Epidemiology, diagnosis, and management. Infection & Chemotherapy, 50(3), 164–177.
• Klein, N., & Vignesh, R. (2020). HIV/AIDS and opportunistic infections. The Journal of Infection, 81(2), 221–237.
• Coates, T., et al. (2019). Guidelines for the prevention and treatment of opportunistic infections in adults and adolescents with HIV. US Department of Health and Human Services.
• Page, J. B., et al. (2021). Pulmonary infections in HIV-infected patients. Clinical Chest Medicine, 42(2), 219–242.
• Antinori, A., et al. (2016). Updated research nosology for HIV-associated nephropathy and HIV-associated immune complex kidney disease. AIDS, 30(12), 1929–1942.