Abstract Introduction Community-acquired pneumonia (CAP) leads to roughly 650 hospitalizations per 100,000 adults annually in the U.S., whereas Legionella occurs at 1.4-1.8 cases per 100,000 worldwide. Legionella, transmitted via inhaled contaminated aerosols, poses heightened risk in those with immunosuppression, chronic lung disease, older age, or substance use, often causing severe, ICU-level illness1. Case Presentation 51-year-old female with cutaneous vasculitis and substance use disorder presented with three days of progressive left-sided abdominal pain, fever, nausea, vomiting, constipation, dark urine, productive cough and dyspnea. Social history was notable for five-pack-year smoking history and non-prescription opioid use, discontinued three days prior to presentation. A rapid response was activated for a National Early Warning Score of 5. She was febrile, tachypneic, and tachycardic, prompting ICU admission for acute hypoxemic respiratory failure requiring intubation. Empiric antibiotics with vancomycin, piperacillin-tazobactam, and azithromycin were initiated. Legionella urinary antigen returned positive, and Infectious Disease recommended adding rifampin. Therapy was narrowed to moxifloxacin. Patient developed severe Acute Respiratory Distress Syndrome (ARDS) secondary to Legionella pneumonia, requiring deep sedation, neuromuscular blockade, and proning for refractory hypoxemia, with a nadir P/F ratio of 116. Adjunctive care included ventilation adjustments, electrolyte repletion for an single episode of hypophosphatemia (1.8 mg/dL), diuresis to maintain negative fluid balance, and sedation weaning as able to. By hospital day 5, her P/F ratio improved, allowing her to transition to supine position and discontinuation of paralytics. Continued recovery enabled extubation on high-flow nasal cannula at FiO2 50%. She remained hemodynamically stable and was transferred to intermediate care shortly thereafter. Discussion Patient was immunocompromised due to her vasculitis and substance use. Substance use specifically is associated with higher rates of ICU admission and mortality with legionella pneumonia2. Other influencing factors include high APACHE II score at admission (15), hyponatremia (Na ≤ 136), need for mechanical ventilation, and delayed initiation of effective therapy3. This patient only missed delayed initiation in care, making her a significantly higher mortality risk. The most likely source of Legionella infection here is inhalation of aerosolized water from contaminated residential or healthcare water systems, although aspiration of contaminated water is also a recognized route, particularly in someone with substance use disorder4. Legionella pneumonia is a disease that needs quick action in order to prevent it, but quick action to treat it as well. Conclusion Early recognition of Legionella pneumonia and prompt targeted therapy are critical. Substance use and immunosuppression increase severity and risk for refractory ARDS. This abstract is funded by: None
Litsky et al. (Fri,) studied this question.