What causes antibiotic resistance? - Kevin Wu

細菌如何對抗生素產生抗藥性—吳凱文 (Kevin Wu)

譯者: 葉 Yah 宇倫 審譯者: Regina Chu

What if I told you there were trillions of tiny bacteria all around you?

如果我跟你說你身邊 有億萬個看不見的細菌呢？

It's true.

這是真的

Microorganisms called bacteria were some of the first life forms

這些名叫細菌的微生物

是最早出現在地球上的生物之一

to appear on Earth.

Though they consist of only a single cell,

雖然它們只由一個細胞所構成

their total biomass is greater than that of all plants and animals combined.

它們的總生物量 卻大於所有動植物的總和

And they live virtually everywhere:

它們還存在於世界上的每一個角落

on the ground, in the water,

地上、水裡、廚房桌上、你的皮膚上

on your kitchen table, on your skin,

even inside you.

甚至在你身體裡面

Don't reach for the panic button just yet.

不過別緊張

Although you have 10 times more bacterial cells inside you

雖然你體內細菌的數量 是人體細胞的十倍

than your body has human cells,

這些細菌大多數是無害的

many of these bacteria are harmless or even beneficial,

甚至對你有益 幫助消化並增強你的免疫系統

helping digestion and immunity.

但有少數害群之馬能使你患上傳染病

But there are a few bad apples that can cause harmful infections,

from minor inconveniences to deadly epidemics.

造成一些身體的不適 甚至極為致命的流行病

Fortunately, there are amazing medicines designed to fight bacterial infections.

不過幸運的是 我們有抵抗細菌傳染病的藥物

Synthesized from chemicals or occurring naturally in things like mold,

科學家從化學物質 或自然物質如黴菌合成的抗生素

these antibiotics kill or neutralize bacteria

能阻止細胞壁的合成

by interrupting cell wall synthesis

或妨礙蛋白質合成等重要機能 來消滅細菌或中和毒素

or interfering with vital processes like protein synthesis,

all while leaving human cells unharmed.

而不對人體細胞造成任何傷害

The deployment of antibiotics over the course of the 20th century

二十世紀抗生素的發展運用

has rendered many previously dangerous diseases easily treatable.

使許多曾經非常棘手的 疾病變得容易治療

But today, more and more of our antibiotics

但今天，我們的抗生素

are becoming less effective.

卻逐漸失去以往的效果

Did something go wrong to make them stop working?

是哪裏出錯了呢？

The problem is not with the antibiotics but the bacteria they were made to fight,

問題的所在不是在抗生素 而是在細菌的身上

and the reason lies in Darwin's theory of natural selection.

而其中的原因來自達爾文的天擇說

Just like any other organisms,

就像任何其他的物種 細菌也能發生隨機的突變

individual bacteria can undergo random mutations.

Many of these mutations are harmful or useless,

大多數的突變對生物本身有害或無用

but every now and then, one comes along that gives its organism

但每隔一段時間

突變會增強這些生物的生存力

an edge in survival.

And for a bacterium,

a mutation making it resistant to a certain antibiotic

對細菌而言，抗藥性的突變

gives quite the edge.

使它們更勝一籌

As the non-resistant bacteria are killed off,

在醫院這種充滿抗生素的環境裏

which happens especially quickly in antibiotic-rich environments,

缺乏抗藥性的細菌會被迅速消滅

like hospitals,

讓抗藥性的細菌

there is more room and resources for the resistant ones to thrive,

有更多空間和資源去繁殖

passing along only the mutated genes that help them do so.

將優越的突變基因傳給下一代

Reproduction isn't the only way to do this.

而繁殖也不是唯一的方式

Some can release their DNA upon death to be picked up by other bacteria,

有些細菌死後會釋放它們的 DNA 讓其他細菌重組利用

while others use a method called conjugation,

更有細菌會用一種叫接合的方法

connecting through pili to share their genes.

通過細菌線毛的連接 來傳播彼此的基因

Over time, the resistant genes proliferate,

時間一過，耐藥的基因擴散開來 從而創造抗藥的超級細菌

creating entire strains of resistant super bacteria.

那麼，我們有多少時間 來阻止這些超級細菌出現呢？

So how much time do we have before these superbugs take over?

Well, in some bacteria, it's already happened.

這在一些細菌身上已經發生了

For instance, some strands of staphylococcus aureus,

例如能引起皮膚感染、肺炎

which causes everything from skin infections to pneumonia and sepsis,

和敗血症的金黃色葡萄球菌，

have developed into MRSA,

已經變異成抗藥性金黄色葡萄球菌 （簡稱 MRSA ）對盤尼西林

becoming resistant to beta-lactam antibiotics,

二甲苯青黴素、新青黴素 Ⅱ 等 β-內醯胺類抗生素有抗藥性

like penicillin, methicillin, and oxacillin.

Thanks to a gene that replaces the protein beta-lactams normally target and bind to,

多謝於一個取代 β-內醯胺

結合蛋白的突變基因

MRSA can keep making its cell walls unimpeded.

MRSA 能在没有妨碍下 不斷產生細胞壁

Other super bacteria, like salmonella,

其他的超級細菌，像沙門氏菌

even sometimes produce enzymes like beta-lactams

甚至能製造類似 β-內醯胺的酶

that break down antibiotic attackers before they can do any damage,

在抗生素產生功效前 摧毀它們的構造

and E. coli, a diverse group of bacteria

而大腸桿菌是一種能引起 腹瀉和腎功能衰竭的多元菌種

that contains strains that cause diarrhea and kidney failure,

can prevent the function of antibiotics,

能防止喹啉酮等進入細菌細胞

like quinolones, by actively booting any invaders

妨礙抗生素發生功能

that manage to enter the cell.

But there is good news.

但有好消息

Scientists are working to stay one step ahead of the bacteria,

科學家不斷的在研究 比細菌領先一步的方法

and although development of new antibiotics

雖然近年來新抗生素的研發變得緩慢

has slowed in recent years,

the World Health Organization has made it a priority to develop novel treatments.

世界衛生組織已把 新療法的研發立為優先

其他的科學家則研究不同的解決方法

Other scientists are investigating alternate solutions,

such as phage therapy or using vaccines to prevent infections.

像噬菌體療法 或利用疫苗來預防感染

Most importantly, curbing the excessive and unnecessary use of antibiotics,

最重要的是，避免濫用抗生素

such as for minor infections that can resolve on their own,

依靠身體的自然免疫系統 來對付較輕的感染

as well as changing medical practice to prevent hospital infections,

或是改變醫療行為來防護院內感染

can have a major impact

都能維持非抗藥細菌的生命力

by keeping more non-resistant bacteria alive

as competition for resistant strains.

增加其對抗藥性細菌的競爭力

In the war against super bacteria, deescalation may sometimes work better

這場對抗超級細菌的戰爭 使用降階療法

than an evolutionary arms race.

或許比進化競賽的效果更好