使用過濾器防治退伍軍人桿菌之成效探討

Effectiveness of Legionella Control Using Filters

退伍軍人桿菌屬（Legionellaceae）為水中常在的細菌，是小且多形型的格蘭氏陰性桿菌，常由自然界環境中的藻類和水生細菌獲得生長所需的營養來源，存在於25～50℃的水中，此菌最佳生長溫度為35～45℃，PH 2.0～8.5中生存，此菌常造成醫院內伺機感染，病人多經由被汙染的水霧吸入或嗆入而造成呼吸道感染，導致退伍軍人桿菌肺炎。台灣地處亞熱帶，平均氣溫高過25℃，幾乎整年都處在退伍軍人桿菌適合生長的溫度，社區肺炎由退伍軍人桿菌所致的比率為2～15%，在台灣，住院之社區感染肺炎患者約有9%為退伍軍人桿菌所致。中部某醫學中心參酌國內外經驗及控制政策，擬定醫院高風險病房之退伍軍人菌防治政策，選定2間高風險病房於水管出水口前約60公分處裝上本院自組過濾器（小孔直徑分別為5 µm、1 µm及0.2 µm）。其後再裝頗爾過濾器（小孔直徑0.2 µm），並選定1間高風險病房作為對照組，平均每隔5日採檢1次，持續監測6個月，實驗組之檢測結果皆為陰性，經由4道過濾器過濾後，水中不再發現退伍軍人桿菌，顯示此過濾裝置確實有阻絕退伍軍人桿菌的效果，成本上比銅銀離子法節省，與其他消毒方式（如臭氧、二氧化氯…）比較，本法沒有副作用，不必擔心人體的傷害，其缺點是僅適用於管路末端水龍頭且使用一段時間以後，水量會變小。因此較適合單點處理，但無法解決全院供水系統問題。

The genus Legionella represents a group of pathogenic, gram-negative bacteria, including L. pneumophila, the causative agent of Legionnaires’ disease. Legionella spp. are commonly found in the environment, including in soil and aquatic systems. Legionnaires’ disease is an infection most common among immunocompromised individuals who inhale Legionella-contaminated aerosols. Based on prior research, a medical center in central Taiwan developed a special filter combination to control Legionella in wards caring for patients with a high infection risk. The filter assembly comprised 3 filters with different pore sizes, placed approximately 60 cm in front of pipe outlets, with an additional Pall filter behind the filter assembly. These filter assemblies were placed in 2 high-risk patient wards. Another ward, also with high-risk patients, served as the control group. Over a 6-month period, water sampling was conducted every 5 days. The outlet water cultures were all Legionella-negative in the experimental group. There are other methods for controlling Legionella, including copper-silver ionization and chlorination. However, the efficacy of these filter assemblies was superior to the other methods.