Are you one of those hosts who’s 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?

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.

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 said.

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

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.

But despite the horrifying picture this paints of microbe-infested interiors, the research doesn’t actually give us anything too serious to worry about.

“For a healthy individual, bacteria on shoes likely pose no or minimal risk,” said Kevin Garey, 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.

However, 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 said. “In a person who is at risk for infections — usually someone recently hospitalized — attention to good household cleaning can be important.

“For most healthy persons, however, you can make the decision as much based on preference and habit, as potential health concern.”

Words to Learn 相关词汇

【难题】nántí conundrum a confusing and difficult problem or question

【普遍存在的】pǔbiàn cúnzài de ubiquitous present, appearing, or found everywhere

客人跨进家门的时候，你是否也纠结过这个难题：应不应该让他们脱鞋呢？

首先，没有必要掩饰事实：美国亚利桑那大学环境微生物学研究专家乔纳森•塞克斯顿表示，普通的鞋子上“每平方英寸有数十万的细菌”，我们的鞋底通常都聚集着大量的细菌，我们每迈出一步，鞋底都会粘上新的细菌。塞克斯顿说：“不管你去哪里，鞋底都会粘上细菌。”此前的研究显示，在一些研究样本中，几乎所有鞋子都带有粪便细菌，其中一种主要的细菌为大肠杆菌 —— 研究人员在96%的鞋底上发现了这种细菌。虽然许多类型的大肠杆菌对人类无害，但某些菌株可能导致严重的腹泻、尿路感染甚至脑膜炎。

除了这种普遍存在的细菌，还有一些研究发现了鞋子上存在金黄色葡萄球菌的证据。这种细菌可能导致多种皮肤感染疾病，更让人担忧的是，还会感染血液和心脏。

尽管这幅微生物入侵的画面很可怕，但这项研究实际上并没有给我们带来任何值得担心的严重问题。

美国休斯敦大学药学院教授凯文•加里说：“对于健康的人来说，鞋子上的细菌并不会构成风险，或者说风险很小。”

塞克斯顿说，健康的人通常需要接触很多有害细菌菌株才会真正感染。

但是加里说，如果你有感染的风险，或者你有年幼的小孩，“那么你在进屋时最好把鞋子脱掉。对于可能被传染（一般最近住过院）的人来说，注意室内卫生很重要。”

“不过对大多数健康人来说，你可以根据潜在的健康考量来做决定，也完全可以按照个人喜好和习惯。”

(Chinadaily.com.cn)