某醫學中心嗜肺性退伍軍人桿菌危害研究

Survey on Legionella pneumophila in a medical center

文獻顯示嗜肺性退伍軍人桿菌（Legionella pneumophila）可存在於㊩療院所的冷卻水塔中，亦可能污染其空調系統、供水設備與淋浴蓮蓬頭，使具呼吸道感染且抵抗力較差的人致病。為評估此菌種在㊩院內的暴露現況，並探討可能造成的感染，自民國㈧十㈤年十㈪至民國㈧十六年㈤㈪以某㊩㈻中心為對象，針對胸腔科病房和內科加護中心之195 位住院病人，抽其痰液和血液以進行嗜肺性退伍軍人桿菌培養與抗體檢測；另外亦對該院154 位㊩護人員檢定血液中退伍軍人桿菌抗體效價。該院各大樓之冷卻水塔、供水系統、空調系統以及空氣落塵亦同時進行環境測定。結果顯示在兩位住院病患的抽痰液中分離出嗜肺性退伍軍人桿菌，血清型均為第一型，其血清抗體效價均大於1:256，然此二人均屬於院外感染；其餘193 人的抽痰液中並未分離出嗜肺性退伍軍人桿菌，且其中38 人之血清抗體效價均未大於1:32。另154 名㊩護人員之血清抗體效價亦均未大於1:32。環境測定方面，在22 個冷卻水塔水樣中有12 個水塔培養出嗜肺性退伍軍人桿菌，血清型均為第一型，污染率為54.5％；然貯水池、各病房內的自來水、熱水槽、蓮蓬頭以及空調之空氣落塵中則均未發現嗜肺性退伍軍人桿菌的存在。本研究並無證據顯示嗜肺性退伍軍人桿菌已經由冷卻水而污染空調送風管線並造成人員的感染；然冷卻水塔產生的污染水霧仍可能經由開放通口（如:窗戶）而進入室內。因此，冷卻水塔或貯水設備仍必須定期清洗與消毒，以確保㊩院住院病人和㊩院工作人員免於遭受嗜肺性退伍軍人桿菌之感染。

cooling tower of healthcare facilities and may also contaminate airconditioning system, water-supply equipment and showers, which could cause outbreaks in hospitals. In order to evaluate potential exposure of L. pneumophila, a survey was taken in a medical center between October 1996 and May 1997. One hundred and ninety-five inpatients at the chest medicine wards and ICU wards of internal medicine were selected as the potentially infected subjects. Blood and sputum samples were taken from these subjects to examine the presence of L. pneumophila. Serum samples were also taken from 154 healthcare workers. Environmental measurements of cooling tower system, water-supply equipment and air-conditioning system were performed to identify whether L. pneumophila was present. Results showed that L. pneumophila serotype 1 was only identified from the sputum samples of two inpatients, for which the antibody titer of serum samples was larger than 1:256. Both cases were verified as nonnosocomial infection. The antibody titer of L. pneumophila for all tested healthcare workers was not larger than 1:32. Twelve out of twenty-two tested cooling towers ( 54.5% ) were contaminated by L. pneumophila serotype 1, but L. pneumophila was not isolated from other environmental samples. No evidence was found in this study to show that L. pneumophila passed through the cooling system to contaminate airsupply ducts and to cause human infection. Nevertheless, aerosol mists generated by cooling towers might get into the building via the openings (e.g., windows). Regular cleaning-up and disinfection of the cooling towers are recommended.