浴室噴頭隱藏細菌，特別是分支桿菌Mycobacterium avium,對免疫功能損傷、囊性纖維化或是艾滋病（AIDS）病人、接受癌癥治療或近期器官移植病人就生死攸關了。 In what may be the scariest shower news since Alfred Hitchcock's "Psycho," a study says shower heads can harbor tiny bacteria that come spraying into your face when you wash. People with normal immune systems have little to fear, but these microbes could be a concern for folks with cystic fibrosis or AIDS, people who are undergoing cancer treatment or those who have had a recent organ transplant.

    Researchers at the University of Colorado tested 45 showers in five states as part of a larger study of the microbiology of air and water in homes, schools and public buildings. They report their shower findings in Tuesday's edition of Proceedings of the National Academy of Sciences.

    In general, is it dangerous to take showers? "Probably not, if your immune system is not compromised in some way," lead author Norman R. Pace says. "But it's like anything else - there is a risk associated with it."

    The researchers offer suggestions for the wary, such as getting all-metal shower heads, which microbes have a harder time clinging to.

    Still, shower heads are full of nooks and crannies, making them hard to clean, the researchers note, and the microbes come back even after treatment with bleach.

    People who have filtered shower heads could replace the filter weekly, added co-author Laura K. Baumgartner. And, she said, baths don't splash microbes into the air as much as showers, which blast them into easily inhaled aerosol form.

    It doesn't seem as frightening as the famous murder-in-the-shower scene in Hitchcock's classic 1960 movie. But it's something to be reckoned with all the same.

    The bugs in question are Mycobacterium avium, which have been linked to lung disease in some people.

    Indeed, studies by the National Jewish Hospital in Denver suggest increases in pulmonary infections in the United States in recent decades from species like M. avium may be linked to people taking more showers and fewer baths, according to Pace.

    Symptoms of infection can include tiredness, a persistent, dry cough, shortness of breath, weakness and "generally feeling bad," he said.

    Shower heads were sampled at houses, apartment buildings and public places in New York, Illinois, Colorado, Tennessee and North Dakota.

    The researchers sampled water flowing from the shower heads, then removed them, swabbed the interiors of the devices and separately sampled water flowing from the pipes without the shower heads.

    By studying the DNA of the samples they were able to determine which bacteria were present.

    They found that the bacteria tended to build up in the shower head, where they were much more common than in the incoming feed water.

    Most of the water samples came from municipal water systems in cities such as New York and Denver, but the team also looked at shower heads in four rural homes supplied by private wells. No M. avium were found in those shower heads, though some other bacteria were.

    In previous work, the same research team has found M. avium in soap scum on vinyl shower curtains and above the water surface of warm therapy pools.

    And stay tuned. Other studies under way by Pace's team include analyses of air in New York subways, hospital waiting rooms, office buildings and homeless shelters.

    The research was funded by the Alfred P. Sloan Foundation and the National Institute of Occupational Safety and Health.

    Virginia Tech microbiologist Joseph O. Falkinham welcomed the findings, saying M. avium can be a danger because in a shower "the organism is aerosolized where you can inhale it."

    In addition to people with weakened immune systems, Falkinham also cited studies showing increased M. avium infections in slender, elderly people who have a single gene for cystic fibrosis, but not the disease itself.

    Two copies of the gene are needed to get cystic fibrosis, but having just one copy may result in increased vulnerability to M. avium infection as people age, said Falkinham, who was not part of Pace's research team.

    自Alfred Hitchcock的"驚魂記"以來，在浴室有可怕新聞，一研究說浴室噴頭能隱藏微小細菌，當你洗浴的時候可以噴霧到你的臉上。這對免疫系統正常的人威脅不大，而這些微生物對囊性纖維化或是艾滋病（AIDS）病人、接受癌癥治療或近期器官移植病人就生死攸關了。

    科羅拉多大學研究人員測試了5個州的45個浴室，這是在居室、學校和公共建筑中空氣和水的微生物學更大研究的一部分。他們報告在國家科學院星期二版公報公布了浴室發現結果。

    通常，淋浴有危險嗎？主作者Norman R. Pace 說："大概不會，如果你的免疫系統正常的話"."但就像其它事情一樣-它也伴隨著危險。"

    研究者提出警示，所有的金屬淋浴噴頭，微生物粘附有一定困難。

    然而，研究人員注意到淋浴噴頭充分隱蔽和有裂隙，使它們清潔困難，甚至用漂白劑處理之后微生物依然存在。人們用過濾淋浴噴頭取代每周過濾，合著作者Laura K. Baumgartner說，像陣雨洗澡不會把微生物濺到空氣中，而沖擊它們形成氣霧就容易被吸入。

    沒有看到1960年代Hitchcock經典電影中淋浴場令人恐懼的著名兇殺。但某些事情和預料完全一致。

    涉及某些人肺病有關的分支桿菌（Mycobacterium avium）.

    另外，丹佛國立猶太醫院研究提出美國近數十年肺部感染增加，其中就有M. avium,按Pace所說這與多淋浴少盆浴者有關。

    他說，感染的癥狀包括疲倦、頑固干咳、呼吸短促、虛弱和全身不適。

    紐約、伊利諾斯、科羅拉多、田納西和北達科他的居室、公寓樓和公共場所的淋浴噴頭取樣。

    研究者從淋浴噴頭流水取樣，然后移開它們，擦凈器具內部并把沒有噴頭的管中分別取流水樣品。

    通過樣品DNA研究，他們能測定出有細菌存在。

    他們發現細菌常常在淋浴噴頭中存在，并且比進入給水的細菌要多。

    多數水樣來自紐約、丹佛城市市政供水系統，但小組也從4個農村家庭私人水井供水的淋浴噴頭做了調查。在這些淋浴噴頭雖然有一些其它細菌，但沒有發現M. avium.

    Falkinham還引用其它研究表明，除了免疫系統衰弱者外，有囊性纖維化單個基因的瘦長、老人M. avium感染也有增加，而不是疾病本身。

    不在Pace 研究小組的Falkinham說，囊性纖維化需要這基因兩個拷貝，而恰好其中一個拷貝能使老人更容易感染M. avium.