Publication date: Jul 16, 2026
Opportunistic infections caused by uncommon intracellular pathogens can serve as important clues to underlying immune dysfunction. We report a 57-year-old male who presented with chronic cough, dyspnea, fever, and weight loss. Chest imaging revealed diffuse pulmonary infiltrates and mediastinal lymphadenopathy, mimicking tuberculosis or lymphoma. Despite empirical anti-tuberculosis and broad-spectrum antibiotic therapy, his condition deteriorated. Metagenomic next-generation sequencing (mNGS) and culture confirmed Talaromyces marneffei infection. During antifungal therapy, he developed Legionella pneumophila pneumonia-an unusual sequential infection that raised suspicion of an immune defect. Comprehensive immunological evaluation revealed anti-interferon-γ (anti-IFN-γ) autoantibodies, supporting the diagnosis of AIGA-associated immunodeficiency. The patient had also shown repeatedly indeterminate interferon-γ release assay (IGRA) results, retrospectively suggesting impairment of the IFN-γ pathway. This case illustrates that recurrent or sequential infections with intracellular pathogens, particularly Talaromyces marneffei and Legionella pneumophila, should prompt evaluation for cell-mediated immunodeficiency such as AIGA syndrome. Early recognition may facilitate tailored antimicrobial therapy, immunological follow-up, and consideration of immunomodulatory treatment in selected patients.
Open Access PDF
| Concepts | Keywords |
|---|---|
| Anti–IFN-γ autoantibody | |
| Immunodeficiency | |
| Legionella pneumophila | |
| Talaromyces marneffei |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | Legionella pneumophila infections |
| disease | MESH | Opportunistic infections |
| disease | MESH | chronic cough |
| disease | MESH | dyspnea |
| disease | MESH | fever |
| disease | MESH | weight loss |
| disease | MESH | tuberculosis |
| pathway | KEGG | Tuberculosis |
| disease | MESH | lymphoma |
| disease | MESH | Talaromyces marneffei infection |
| disease | MESH | pneumonia |
| disease | MESH | infection |
| pathway | REACTOME | Release |
| disease | MESH | syndrome |
| pathway | REACTOME | Reproduction |
| disease | MESH | included |
| drug | DRUGBANK | Coenzyme M |
| disease | MESH | malignancy |
| disease | MESH | autoimmune disease |
| disease | MESH | cough |
| disease | MESH | pleural effusions |
| disease | MESH | hyperplasia |
| disease | MESH | inflammation |
| disease | MESH | ecchymosis |
| disease | MESH | fungal infection |
| drug | DRUGBANK | Amphotericin B |
| drug | DRUGBANK | Voriconazole |
| drug | DRUGBANK | Itraconazole |
| disease | MESH | respiratory failure |
| drug | DRUGBANK | Dimercaprol |
| drug | DRUGBANK | Moxifloxacin |
| drug | DRUGBANK | Azithromycin |
| drug | DRUGBANK | Water |