A50-44 Immunosuppression Meets a Rare Foe: Rapidly Progressive Pulmonary Nocardia Otitidiscaviarum Infection

Abstract Nocardia species are opportunistic pathogens that can cause severe pulmonary and disseminated infections, particularly in immunocompromised patients. Diagnosis is often delayed due to nonspecific clinical and radiographic findings, contributing to high morbidity and mortality.1 A 70-year-old woman with systemic lupus erythematosus on prednisone, hydroxychloroquine, and mycophenolate, atrial fibrillation, heart failure with reduced ejection fraction (35%), and end-stage renal disease on hemodialysis presented with five days of diarrhea, dyspnea, cough, and weakness. She denied having a fever.On admission, she was tachycardic (HR 121), blood pressure 136/80, with normal oxygenation. Laboratory data with white blood cell count 17.3k, hemoglobin 9.8 g/dL, platelets 143k, sodium 133 mmol/L, BUN 53 mg/dL, creatinine 2.7 mg/dL, NT-proBNP 162,000 pg/mL. Chest X-ray revealed a 9.1 cm right midlung mass; computed tomography angiography of the chest showed three large bilateral lower lobe cystic consolidations, the largest 8.2 cm in the right lower lobe, suspicious for abscesses (Figure 1A and 1B). She also had a right jugular venous thrombosis.Empiric therapy included vancomycin, meropenem, and TMP-SMX (for Pneumocystis prophylaxis). She required intubation; BAL grew Nocardia otitidiscaviarum, prompting treatment-dose TMP-SMX (Figure 2A and 2B). Despite transient improvement (extubated on day 6), she developed severe sepsis with shock, cytopenias requiring transfusions, disseminated intravascular coagulation, and ultimately expired. This case highlights the aggressive nature of pulmonary nocardiosis in immunocompromised hosts. Imaging findings of cavitary or cystic consolidations should raise suspicion, especially in patients on chronic immunosuppression.2 Early diagnosis and targeted antimicrobial therapy are critical, yet outcomes remain poor in severe cases with disseminated infection.3 Pulmonary nocardiosis should be considered in immunocompromised patients with cavitary lung lesions. Prompt recognition and initiation of targeted therapy may improve survival, but prognosis remains guarded in those with advanced disease. 1. Srivastava, S. et al. Nocardia otitidiscaviarum causing pulmonary nocardiosis: a case report and its review of the literature. Access Microbiology 6, 000530.v5 (2024). 2. Deepa, R., Banu, S. T., Jayalakshmi, G. & Parveen, J. D. Pleuropulmonary nocardiosis due to Nocardia otitidiscaviarum in a debilitated host. Indian journal of pathology & microbiology 59, (2016). 3. Peleg, A. Y. et al. Risk factors, clinical characteristics, and outcome of Nocardia infection in organ transplant recipients: a matched case-control study. Clinical infectious diseases: an official publication of the Infectious Diseases Society of America 44, (2007). This abstract is funded by: N/A