Abstract Introduction Legionella pneumophila can be an underrecognized cause of severe community-acquired pneumonia, particularly in patients with underlying comorbidities. Diagnosis may be delayed due to its nonspecific presentation; however, it can manifest with hyponatremia and altered mental status (AMS). Early recognition and targeted therapy are crucial to improving outcomes, as severe cases can rapidly progress to multiorgan failure and death. Case Description An 81-year-old man with COPD and recurrent hyponatremia related to chronic alcohol use presented with altered mental status and hyponatremia. He was initially admitted to the intensive care unit (ICU) for management of symptomatic hyponatremia which improved with intravenous fluids. After transfer to the medical floor, he developed worsening hypotension and hypoxemia, prompting readmission to the ICU. Chest imaging revealed new bilateral infiltrates concerning for pneumonia. Broad-spectrum antibiotics (ceftazidime, vancomycin, metronidazole) were initiated, and he was placed on high-flow nasal cannula at 100% FiO2. He progressed to septic shock requiring norepinephrine. Urine antigen testing was positive for Legionella pneumophila, and antibiotics were narrowed to levofloxacin. His septic shock resolved within days, and his oxygen requirements improved to 2 L via nasal cannula. While being managed for acute kidney injury secondary to septic shock, his course was again complicated by recurrent hypoxemia and worsening bilateral pulmonary infiltrates. Despite escalation of care including intubation, he developed multiorgan failure and passed away after transition to comfort measures. Discussion Legionella pneumonia can range from mild illness to fulminant respiratory failure. It is frequently associated with hyponatremia, with one large retrospective study showing a 30% incidence. Because our patient had a history of alcohol abuse, recurrent hyponatremia, and no initial signs of pneumonia, it is likely that hyponatremia was the first presenting symptom of infection. Septic shock and ARDS occur in 64.8% and 47.7% of patients, respectively, and are significantly more common among non-survivors. This case illustrates the severe end of the Legionella disease spectrum and highlights the importance of early consideration and testing for Legionella in patients with severe pneumonia. This abstract is funded by: None
Kujundzic et al. (Fri,) studied this question.