退伍軍人桿菌造成的社區型肺炎是一種易被忽略與低估的疾病，但卻可能造成顯著的罹病率與死亡率。一般因退伍軍人桿菌肺炎導致急性呼吸窘迫症候群在臨床上並不常見，本案例為一名59 歲的男性，因重度急性呼吸窘迫症候群由區域醫院轉送至醫學中心，隨後診斷為退伍軍人桿菌感染之社區型肺炎。個案成功地接受了抗生素、肺部保護呼吸器治療策略及支持療法而康復出院。此案例突顯了退伍軍人桿菌肺炎與急性呼吸窘迫症候群之關聯性。此外，藉由此案例的呈現，希望可以加強醫療照護人員對於儘管進行了充分治療的嚴重社區型肺炎合併低血氧症仍持續惡化之重症病患，能早期積極的評估和進一步處置，以改善病患預後。

Legionella pneumonia is a common, usually underreported and undiagnosed cause of community acquired pneumonia which can result in significant morbidity and mortality. Acute respiratory distress syndrome rarely had been associated with Legionella infection. We present a 59-year-old man without systemic underlying disease admitted with severe acute respiratory distress syndrome and he was found to have Legionella pneumonia. He was successfully managed with antibiotics, lung protective strategies, and supportive care. This patient highlights the unusual association of Legionella infection and severe acute respiratory distress syndrome. Additionally, the case re-enforces the need for early and aggressive evaluation and management of patients presenting with community-acquired pneumonia and progressive hypoxia despite adequate treatment.