進屋前要脫鞋嗎?聽聽科學研究怎麼說大綱

Are you one of those hosts who's immediately gripped by this conundrum as your guests step across the threshold into your home: Should you, or shouldn't you, ask them to remove their shoes?

客人跨進家門的時候，你是否也糾結過這個難題：應不應該讓他們脫鞋呢？

On the one hand, it makes you look like a fussy host. On the other, what about the legions of disease-causing bacteria that will gleefully leap off their shoes and inevitably infest your home?

一方面，這讓你看起來像個挑剔的主人。另一方面，如果大量的致病細菌大踏步地隨着鞋子進入你家，並開始滋生，可怎麼辦呢？

Avoiding bacterial invasion at the risk of a little social awkwardness seems like a no-brainer. But are shoe bacteria something we should really be worried about in our homes? Here's what science tells us about how to navigate this conundrum.

冒着一點社交尷尬的風險來避免細菌入侵，這似乎是一個挺容易的選擇題。但是，我們真的需要擔心鞋子帶進家裏的細菌嗎？下面來看看科學家是如何破解這個難題的。

To start with, there's no point in sugarcoating the pill: the average shoe harbors "hundreds of thousands of bacteria per square inch," according to Jonathan Sexton, an environmental microbiologist and research specialist at the University of Arizona.

首先，沒有必要掩飾事實：美國亞利桑那大學環境微生物學研究專家喬納森·塞克斯頓表示，普通的鞋子上“每平方英寸有數十萬的細菌”，

The soles of our shoes are essentially a meet and greet for these microbes, and with each step we take, we pick up new attendants. "Pretty much wherever you go, you're going to be picking up stuff," Sexton told Live Science. (Beware, however: Some places like bathrooms do harbor more bacteria and a greater diversity, he said.)

我們的鞋底通常都聚集着大量的細菌，我們每邁出一步，鞋底都會粘上新的細菌。塞克斯頓告訴趣味科學網站說：“不管你去哪裏，鞋底都會粘上細菌。”（但要注意的是，浴室等地方的細菌更多，種類也更多。）

But exactly what types of bacterial communities are hanging out on our shoes, and do they pose a legitimate health threat?

那麼，我們的鞋底粘的是到底是哪種細菌？它們對我們有健康危害嗎？

Well, previous studies have shown that almost all shoes in some research samples were coated with fecal bacteria, including one prominent bug called Escherichia coli (), which researchers discovered on 96 percent of shoe soles. While many types of are harmless to humans, some strains can cause severe diarrhea, urinary tract infections and even meningitis.

此前的研究顯示，在一些研究樣本中，幾乎所有鞋子都帶有糞便細菌，其中一種主要的細菌爲大腸桿菌——研究人員在96%的鞋底上發現了這種細菌。雖然許多類型的大腸桿菌對人類無害，但某些菌株可能導致嚴重的腹瀉、尿路感染甚至腦膜炎。

"Not necessarily on every shoe, but on a good majority, you can find some type of there," Sexton said.

塞克斯頓說：“並不一定在每隻鞋子上，但在絕大多數鞋子上你都能發現某種大腸桿菌。”

Apart from this ubiquitous germ, other studies have also found evidence of things like Staphylococcus aureus, which underlies a wide range of skin infections, and more worryingly, infections of the blood and the heart.

除了這種普遍存在的細菌，還有一些研究發現了鞋子上存在金黃色葡萄球菌的證據。這種細菌可能導致多種皮膚感染疾病，更讓人擔憂的是，還會感染血液和心臟。

Another prominent study published in 2014 in the journal Anaerobe sampled 30 households in Houston, Texas, for the presence of Clostridium difficile (C. difficile), a bacterium with a long lifespan that commonly causes bowel problems like diarrhea.

在另一項重要的研究中，研究人員採集了30種家用物品的樣本，以檢驗梭狀芽胞桿菌是否存在。梭狀芽胞桿菌的存活期很長，通常會導致痢疾等腸道疾病。這項研究在德克薩斯州休斯頓開展，研究結果於2014年發表在《厭氧菌》期刊上。

Of all the household items they sampled, the researchers found that shoes harbored more C. difficile than even the surface of a toilet — underscoring the power that grubby soles could have to spread germs through a home.

在採集的所有家用品樣本中，研究人員發現鞋子裏的梭狀芽胞桿菌比馬桶表面的還要多，這也證實了髒鞋子在家裏傳播細菌的能力。

But despite the horrifying picture this paints of microbe-infested interiors, the research doesn't actually give us anything too serious to worry about. While many of us might want to launch into a house-cleaning frenzy at the thought of a wayward shoe, the reality is that the load of bacteria our shoes bring indoors isn't typically high enough to make the average healthy person very sick.

儘管這幅微生物入侵的畫面很可怕，但這項研究實際上並沒有給我們帶來任何值得擔心的嚴重問題。許多人也許一想到鞋上的細菌就想來一場大掃除，但事實是，我們的鞋子帶進室內的細菌數量一般都不足以讓普通的健康人生病。

"For a healthy individual, bacteria on shoes likely pose no or minimal risk," said Kevin Garey, the author on the 2014 study and professor at the University of Houston College of Pharmacy. Usually, a healthy person would need to come into contact with thousands of microbes from one harmful bacterial strain to actually become infected with something, Sexton added.

美國休斯敦大學藥學院教授凱文·加里說：“對於健康的人來說，鞋子上的細菌並不會構成風險，或者說風險很小。”凱文·加里也是前述2014年研究報告的作者。塞克斯頓說，健康的人通常需要接觸很多有害細菌菌株纔會真正感染。

Another point is that most of us don't spend a lot of time on the ground, where shoe bacteria dwell. "The exposure makes the poison. So if you're not exposed to it, you're not going to get sick from it," Sexton said. In some cases, layers of bacteria coating the floor can become "re-aerosolized" and enter the air we breathe, lifted by the draft from a window, for instance, Sexton explained. That might increase infection risk. But the greatest threat really lies on the ground. "I'd be more worried about a child crawling around on the floor. For a healthy adult, it's not too big of an issue," Sexton said.

另一點是，大多數人不會在地面上待很久，而地面正是鞋子攜帶細菌的主要聚集場所。塞克斯頓說：“接觸纔會導致感染。所以如果你沒有接觸，就不會因此生病。”他解釋說，在某些情況下，地面上覆蓋的一層細菌可能會因從窗外進來的一股氣流而“重新霧化”，從而進入我們呼吸的空氣。這可能增加感染風險。但最大的威脅實際上還是在地面上。他說：“我更擔心的是在地板上爬來爬去的孩子。而對於健康的成年人來說，這不是太大的問題。”

Another group of people who may need to take extra precautions are those who are immunocompromised, meaning their defenses against infection are lower than usual. "In a person who is at risk for infections — usually someone recently hospitalized — attention to good household cleaning can be important," said Garey.

免疫功能不全的人們也需要格外防範，他們抵抗感染的能力比普通人要低。加里說：“對於可能被傳染（一般最近住過院）的人來說，注意室內衛生很重要。”

In summary, if you're at risk of infection, or you have a small child, "it would be a good idea to take your outdoor shoes off when you enter your home," Garey told Live Science. "For most healthy persons, however, you can make the decision as much based on preference and habit, as potential health concern."

總而言之，加里告訴趣味科學網站說，如果你有感染的風險，或者你有年幼的小孩，“那麼你在進屋時最好把鞋子脫掉，不過對大多數健康人來說，你可以根據潛在的健康考量來做決定，也完全可以按照個人喜好和習慣”。

And it's worth remembering that bacteria exist elsewhere than on our shoes: They're in the air, on our skin, in our hair and inside our very guts. In fact, we live in a constantly swirling bacterial soup that would be impossible to completely disinfect.

要記住，細菌不僅存在於鞋子上：它們還存在於空氣中、我們的皮膚上、頭髮上、還有腸道里。實際上，我們一直與細菌共存，完全徹底的消毒是不可能的。

"Healthy bacteria in our gut, skin and elsewhere keep us healthy and protect us from other bacteria that can cause us illness," Garey said. "I don't think everyone appreciates that some bacteria are also good for us."

加里說：“我們的腸道和皮膚等處都有有益健康的細菌，使我們保持健康，免遭致病細菌的侵害。我並不認爲所有人都知道有些細菌對我們是有好處的。”