细菌抵抗性演变演变的细菌 -- -- 先进

What is a superbug?
::什么是超级虫?

Though this dragonfly is a large "bug", it is not harmful. A superbug, on the other hand, is not an insect at all, but a or other microorganism that can be difficult to treat, leading to serious issues. These can be very harmful.
::尽管这只是一个巨大的“虫 ” , 但它并不有害。 另一方面,超级虫根本不是昆虫,而是可能难以治疗的微生物或其他微生物,导致严重的问题。 这些问题可能非常有害。

Evolution of Resistance
::抵抗力量的演变

As evolution continues today, some new may develop and, although beneficial to the species, may be harmful to humans and other . In an almost unprecedented case in May 2007, United States government agencies put a US citizen on a no-fly list, urged border agents to detain him, failed to detect his re-entry into the US, and eventually ordered him into involuntary isolation, urging individuals who had flown with him on several international flights to be tested for XDR-TB. Why were such drastic measures needed? What is XDR-TB, and how did it originate? The answers reveal evolution in action today - in a way that all of us need to understand for our own well-being.
::随着今天的演变,一些新的发展可能有所发展,虽然对物种有益,但对人类和其他有害。 在2007年5月的几乎史无前例的一起案例中,美国政府机构将一名美国公民列入禁飞名单,敦促边防人员拘留他,未能发现他重新进入美国,并最终命令他非自愿地与世隔绝,敦促与他一起搭乘若干国际航班的人接受XDR-TB测试。为什么需要如此严厉的措施?XDR-TB是什么?XDR-TB的起源是什么?答案揭示了今天行动的发展变化 — — 我们大家都需要了解我们自身福祉的方式。

Tuberculosis (TB) has infected and killed humans since at least the year 4000 BCE. Today, over one-third of the world’s has been exposed to the bacterium which causes tuberculosis ( Figure ), but 90% carry the microorganism without symptoms. In the past, the 10% who did develop the characteristic lung infection had a 50% chance of dying. The advent of antibiotics in the mid-20 ^th century dramatically improved survival rates, although the slow-growing bacteria required treatments of 6-12 months rather than days. Just 40 years later, in the 1990s, a new strain appeared with a mortality rate comparable to lung – up to 80%. MDR-TB, or multi- drug resistant TB, is not treatable by two of the most effective anti-TB antibiotics. Then, circa 2000, a second, more menacing strain emerged. XDR-TB, or extensively drug-resistant TB, is neither treatable by the two major drugs nor the less-effective “second line” drugs now used to treat MDR-TB. Late in 2006, an epidemic of XDR-TB developed in South Africa. Currently there are no available drugs that can effectively treat this strain of TB.
::结核病(TB)至少自4000 BCE(BCE)年至少4000年以来就已经感染和杀害了人类。 今天,世界上三分之一以上的人接触了导致肺结核(Figure ) 的细菌,但90%携带的微生物没有症状。 在过去,10%的肺部特质感染者有50%的死亡机率。 20世纪中叶,抗生素的出现大幅提高了存活率,尽管缓慢生长的细菌需要6-12个月而不是几天的治疗。 仅仅在40年后,在1990年代,一种新的菌株出现,其死亡率可与肺部相比 — — 高达80 % 。 多药抗性肺结核(MDR-TB)无法被两种最有效的抗肺结核抗药剂治疗。 接着,Circa 2000年,又出现了一种更危险的菌株。 XDR-TB(XD-TB)或广泛的抗药性结核病(TB)既不能被两种主要药物治疗,也不能被目前用于治疗MDR-TB的低效的“第二线”药物治疗。 2006年晚些时候,南非的XDR-TB(TB)传染病的流行是无法有效治疗的。

Clearly these strains of TB are new and changing rapidly. The evolution of resistance is a growing problem for many disease-causing bacteria and also for parasites , , , and cancer . The “miracle” of drug treatment which appeared to protect humans from disease may be short-lived. How does resistance happen? How can we prevent it?
::显然,这些肺结核菌株是新的,变化很快。 抗药性的演变对于许多致病细菌以及寄生虫、寄生虫和癌症来说是一个日益严重的问题。 似乎能保护人类免受疾病影响的药物治疗的“奇迹”可能是短命的。 抗药性是如何发生的?我们如何预防呢?

First, recognize that antibiotic resistance describes the bacterium, not the human. Bacteria reproduce much more rapidly than humans, and therefore can evolve much more rapidly. Consider a population of bacteria infecting an individual with tuberculosis. Like all populations, individuals within that population show variation. add more variation. By chance, mutation may change the chemistry of one or a few bacteria so that they are not affected by a particular antibiotic. If the infected human begins to take antibiotics, they change the environment for the bacteria, killing most of them. However, the few bacteria which by chance have genes for resistance will survive this change in environment, and they will produce offspring which also carry the genes. More and more of the bacterial population will be resistant to antibiotics because the antibiotics select for resistance. The bacteria are merely evolving in response to changes in their habitats . If the resistant bacteria are transmitted to another human “habitat,” their population continues to expand, and if the new “habitat” takes different drugs, may result in multi-drug resistance ( Figure ).
::首先,承认抗生素抗药性可以描述细菌,而不是人类。细菌的繁殖速度比人类要快得多,因此可以更快地发展。考虑细菌感染肺结核的人群。与所有人群一样,该人群中的个人表现出差异。增加更多的变化。偶然地,突变可能会改变一种或几种细菌的化学特性,使其不受特定抗生素的影响。如果受感染的人开始服用抗生素,它们就会改变细菌的环境,杀死大部分细菌。然而,少数有抵抗基因的细菌会存活下来,它们也会产生遗传基因的后代。越来越多的细菌将抗抗生素,因为抗生素选择抗生素是为了抵抗。细菌只是随着栖息地的变化而演变。如果抗菌细菌被传染给另一个人类的“生境 ” , 它们的人口会继续扩大,如果新的“生境”服用不同的药物,它们可能会导致多种药物的抗药性(Figure ) 。

Superbugs
::超级错误

How widespread is the problem? Staphylococcus aureus bacteria first showed resistance to penicillin just four years after the drug was put to use; today, some strains have shown resistance to nearly all antibiotics. These are now classified as one of several known superbugs. However, resistance is not just limited to bacteria. The Human Immunodeficiency Virus (HIV) has become resistant to several antiviral drugs , and cancer cells within an individual often evolve resistance to chemotherapy drugs. Pesticide resistance is evolving in a similar manner; U.S. crop losses to insect pests have increased from 7% in the 1940s to more than 13% in the 1980s, despite the use of more types of pesticides in the 1980s.
::问题有多普遍?在药物投入使用仅仅四年之后,Staphylococccccus aureus细菌首次表现出对青霉素的抗药性;今天,一些菌株表现出对几乎所有抗生素的抗药性。现在,这些菌株被归类为已知的超级虫之一。然而,抗药性并不限于细菌。人体免疫机能丧失病毒(HIV)已经对几种抗病毒药物产生抗药性,个人体内的癌症细胞往往会演变成对化疗药物的抗药性。农药抗药性正在以同样的方式演变;美国虫害的作物损失从1940年代的7%上升到1980年代的13%以上,尽管1980年代使用了更多的杀虫剂。

What can we do about this particular instance of evolution which we have unwittingly encouraged? In general, we should reduce the use of antibiotics where possible and safe in order to lessen the selective pressure on bacteria. Here are some practices to keep in mind:
::对于我们无意中鼓励的这一特定的演进事例,我们可以做些什么?一般而言,我们应该在可能和安全的情况下减少抗生素的使用,以减少对细菌的选择性压力。

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1. Don’t take antibiotics for viral infections such as colds and flu; they act only on bacteria.
   ::不要为感冒和流感等病毒感染服用抗生素,
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2. When antibiotics are appropriate, take them exactly as prescribed, and complete the entire course.
   ::当抗生素适合时,按规定使用抗生素,完成整个课程。
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3. Never take antibiotics which are left over from an earlier illness or prescribed for someone else.
   ::永远不要吃以前疾病留下的抗生素或给别人开的处方。
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4. Consider purchasing meats and other animal products from animals not treated with antibiotics.
   ::考虑从未接受抗生素治疗的动物购买肉类和其他动物产品。
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5. Consider purchasing organic produce, which is not treated with pesticides.
   ::考虑购买不使用农药处理的有机农产品。
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6. Resist the use of pesticides in your own gardens.
   ::在自己的花园里抵制使用杀虫剂。

We have unintentionally sped up the evolution of microorganisms, but at the same time, their of resistance has given us a window into the process which underlies all changes in life: the process of natural selection.
::我们无意中加快了微生物的进化,但与此同时,他们的抵抗使我们进入了生命所有变化的基础:自然选择过程的进程。

Summary
::摘要

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• Bacteria have developed serious levels of resistance to antibiotics because humans have introduced a new selective force into their environments (our bodies).
  ::细菌对抗生素的抗药性发展得非常严重,因为人类在其环境(我们的身体)中引进了新的选择性力量。
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• An individual bacterium has its own set of genes. If these genes do not confer resistance to antibiotics, the bacterium by itself cannot develop resistance. A population can develop resistance if some of its members have, by chance, the gene for resistance.
  ::个体细菌有自己的基因组。 如果这些基因不产生抗抗生素的抗药性,则细菌本身不能产生抗药性。 如果某些成员偶然拥有抗生素基因,人口可以发展抗药性。
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• The evolution of antibiotic resistance has already resulted in a number of bacteria resistant to most known antibiotics; these are sometime called “superbugs.”
  ::抗生素抗药性的演变已经导致产生了一些耐最著名的抗生素的细菌;这些细菌有时被称为“超级虫”。

Review
::回顾

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1. Use the concept of natural selection to explain the resistance of bacteria to antibiotics and insects to pesticides.
   ::利用自然选择的概念来解释细菌对抗生素和昆虫对杀虫剂的抗药性。
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2. Explain why an individual bacterium cannot on its own change from sensitive to resistant to antibiotics.
   ::解释为什么单种细菌本身不能从敏感到抗药性转变为抗生素。
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3. Choose two actions you think would be most likely to control the increase in antibiotic resistance, and support your choices with examples from your own experience.
   ::选择两种你认为最有可能控制抗生素抗药性增加的动作, 并以自己经验的例子支持你的选择。