C57-08 A Rare Case of Legionella Longbeachae Pneumonia Linked to Indoor Plant Exposure

Abstract Introduction Legionella longbeachae is an uncommon cause of community-acquired pneumonia in the United States, often associated with exposure to soil or potting mix rather than contaminated water sources typical of Legionella pneumophila. Due to its rarity and nonspecific presentation, accounting for only 0.3-3% of Legionella infections diagnosis is often delayed, potentially leading to severe respiratory failure. Case Presentation A 47-year-old man with a history of tobacco use disorder and kratom use presented with worsening shortness of breath, fever, and productive cough. Symptoms began shortly after working in his attic furnace. Initial chest Xray at an outside hospital showed right-sided infiltrates, and laboratory evaluation revealed leukocytosis, elevated procalcitonin and lactic acidosis. Despite empiric broad-spectrum antibiotics initially with a ceftriaxone and azithromycin, later escalated to cefepime and vancomycin his respiratory status deteriorated, prompting transfer to our facility. On arrival, he was hypoxemic (SpO2 80s on OptiFlow), tachycardic, and in respiratory distress. Repeat chest Xray showed diffuse progressive bilateral infiltrates. Despite broad-spectrum coverage the patient developed severe hypoxemia and was intubated for acute respiratory failure. Workup including Legionella urine antigen, respiratory cultures, bronchoscopy with BAL was negative; further delaying the diagnosis. Serial Xrays continued to show worsening multifocal pneumonia. CT chest then performed revealed diffuse ground glass opacities and consolidative changes consistent with multifocal pneumonia. Given his progressive course and unclear etiology, a plasma cell free DNA test was obtained, which showed Legionella longbeachae. He transitioned to levofloxacin with marked clinical improvement. After extubation,the patient was successfully weaned to nasal cannula oxygen and discharged on oral levofloxacin to complete a 14-day course. On further questioning, he reported owning approximately 120 indoor houseplants, representing an exposure source. Discussion This case highlights Legionella longbeachae as an underrecognized cause of severe pneumonia in patients without traditional Legionella risk factors. Unlike L. pneumophila, which is waterborne, L. longbeachae is associated with soil and potting media exposure. The patient’s extensive houseplant collection likely served as the environmental reservoir. Diagnosis requires a high index of suspicion, as standard urine antigen tests detect only L. pneumophila serogroup-1. Advanced diagnostic modalities such as Karius testing or PCR-based methods are invaluable for pathogen identification. Conclusion Clinicians should consider Legionella longbeachae in severe community-acquired pneumonia, particularly in patients with soil or indoor plant exposure highlighting the importance of a detailed environmental history in otherwise healthy patients. Early identification and targeted therapy are crucial to reduce morbidity and prevent unnecessary broad spectrum antibiotic use. This abstract is funded by: None