A46-15 A Rare Case of Nocardia Farcinica Empyema in an Immunocompromised Host

Abstract Introduction Nocardia farcinica is an uncommon species of Nocardia capable of causing localized or disseminated infections involving the lungs, brain, and skin. Predisposing factors include prolonged corticosteroid use, solid-organ transplantation, and other immunocompromised states. Pneumonia is the most frequent clinical manifestation, and only a few cases of pleural involvement have been described in the literature. Case Presentation A 36-year-old man on chemotherapy for Stage IV colon cancer metastatic to the lungs and brain presented with progressive dyspnea and pleuritic chest pain. On examination, he was in acute respiratory distress with decreased breath sounds over the right hemithorax. Chest x-ray demonstrated numerous bilateral pulmonary nodules/masses, bilateral hilar lymphadenopathy, and a small right pleural effusion. Chest computed tomography showed interval enlargement of the right pleural effusion Fig. 1 compared with prior imaging. Thoracentesis yielded 400 mL of serosanguineous fluid, which was sent for cytology, analysis, and culture. Fluid studies were consistent with an exudative fluid with pH 7.47, lactate dehydrogenase (LDH) 1,168 U/L, protein 2.8 g/dL, glucose 128 mg/dL, cytology negative for malignant cells, RBC of 14,000 cells/ µL, and a WBC count of 21,000 cells/µL (91% neutrophils). Aerobic cultures grew branching gram-positive rods, raising concern for Actinomyces or Nocardia infection. Although Actinomyces is an obligate anaerobic organism, we noted that anaerboic cultures often require a longer incubation period to yield growth; therefore, emperic therapy with ceftriaxone and trimethoprim-sulfamethoxazole (TMP-SMX) was initiated to provide coverage for both organisms while awaiting final culture results. A right-sided pigtail catheter was subsequently placed for drainage. Fluid cultures later confirmed Nocardia farcinica, ceftriaxone was therefore discontinued, and TMP-SMX was continued. Magnetic resonance imaging of the brain was ordered to exclude abscess formation. Following discussion with the palliative care team, the patient elected to pursue hospice care. Considering the risk of TMP-SMX induced hyperkalemia during prolonged therapy, palliative amoxicillin-clavulanate monotherapy was prescribed for symptom control. Discussion Nocardia farcinica empyema is a rare but serious infection that typically affects immunocompromised or chronically ill patients. Diagnosis requires a high index of suspicion and molecular confirmation, as delayed identification can lead to worse outcomes. Management generally involves prolonged therapy with TMP-SMX, guided by susceptibility testing, and may require combination antibiotics or surgical drainage in advanced cases. Early recognition and individualized management are essential to improve prognosis, given the organism’s potential for dissemination and antimicrobial resistance. This abstract is funded by: None