D107-15 Mowing Into Trouble: A Rare Case of Pulmonary Tularemia Presenting With Empyema

Abstract Introduction Tularemia is a rare zoonotic infection caused by Francisella tularensis, with pulmonary involvement being an uncommon but severe manifestation that may mimic atypical infections or malignancy. Prompt recognition/treatment are critical given its high morbidity and mortality. This case highlights the diagnostic challenges of pleuropulmonary tularemia in a patient with known environmental and occupational exposures. Case Presentation A 66-year-old man with alcohol use disorder presented with one week of dyspnea, weakness, fevers, and chills. He denied travel or sick contacts but worked as a landscaper in rural Maryland. On arrival, he was febrile (39.4 °C), hypotensive, tachycardic, tachypneic, and hypoxic on 4 L nasal cannula. Labs showed hyponatremia (Na 125 mmol/L), acute kidney injury (BUN/Cr 68/4.71 mg/dL), transaminitis (AST/ALT 257/84 U/L), thrombocytopenia (86 × 10³/µL), mild hyperbilirubinemia (1.5 mg/dL), and leukocytosis (12 × 10³/µL). CT chest revealed a right upper lobe mass-like consolidation with moderate pleural effusion (Fig 1). He was started on broad-spectrum antibiotics and transferred to the ICU for support. Thoracentesis drained 410 mL of cloudy fluid consistent with empyema (WBC 8,096/µL 74% neutrophils, pH 7.21, LDH 4,914 U/L). Blood cultures grew Aggregatibacter species, and pleural cultures showed fastidious gram-negative rods. Cytology was negative for malignancy, and antibiotics were narrowed to ceftriaxone. Due to persistent effusion, a chest tube was placed, followed by VATS decortication revealing dense adhesions and fibrinopurulent debris. Final pleural cultures grew Francisella tularensis, prompting the laboratory to re-evaluate the previously identified Aggregatibacter isolate for possible misidentification, after which prior blood cultures were also determined positive for F. tularensis. Tularemia serologies (IgM and IgG) confirmed the diagnosis. The patient was transitioned to ciprofloxacin for a two-week course, with marked clinical and radiologic improvement. Discussion Tularemia is rare in the U.S. (incidence below 0.064 per 100,000 annually). While ulceroglandular and typhoidal forms predominate, pulmonary tularemia causing pneumonia or empyema is exceedingly uncommon, with mortality up to 60% if untreated. Risk factors include landscaping, farming, and hay-handling. Mowing or disturbing infected animal nests can aerosolize F. tularensis, leading to inhalational exposure, a key mechanism in this case. Radiographically, it may mimic malignancy, and cultures are challenging due to the organism’s fastidious nature and frequent misidentification. Empyema occurs in fewer than 5% of cases. Clinicians should maintain a high index of suspicion and consider PCR or serologic testing for F. tularensis in severe pneumonia or empyema with possible aerosol exposure, particularly among landscapers and farmers in endemic regions. This abstract is funded by: None