自然界中耐抗生素細菌的起源

An evolutionary battle between fungi and bacteria on hedgehogs' skin gave rise to a type of antibiotic-resistant bacteria long before humans started using the antibiotics that were thought to lead to such superbugs, a new study reveals.

一項新的研究顯示，早在人類開始使用抗生素之前，真菌和細菌在刺猬皮膚上的一場進化之戰(zhàn)就產(chǎn)生了一種耐抗生素細菌，人們認為這種抗生素會導(dǎo)致超級細菌。

Researchers traced some lineages of the superbug MRSA, or methicillin-resistant Staphylococcus aureus, to a parasitic fungus found on the skin of European hedgehogs (Erinaceus europaeus).

研究人員追蹤了超級細菌MRSA或耐甲氧西林金黃色葡萄球菌的一些譜系，并發(fā)現(xiàn)歐洲刺猬皮膚上的一種寄生真菌(Erinaceus europaeus)。

The fungus secretes antibiotics to fight and kill Staphylococcus aureus bacteria (also found on hedgehogs); to stay alive, the bacteria, in turn, evolved antibiotic resistance that later crossed into livestock and humans, the research team reported in a new study.

這種真菌會分泌抗生素來殺死金黃色葡萄球菌;研究小組在一項新研究中報告說，為了生存，細菌反過來進化出抗生素耐藥性，后來又傳到了牲畜和人類身上。

While the use of antibiotics often drives the evolution of superbugs, this study shows the origins of some antibiotic-resistant bacteria in nature.

雖然抗生素的使用通常會推動超級細菌的進化，但這項研究揭示了自然界中耐抗生素細菌的起源。

"We know the resistance genes got into pathogen genomes before humans were using antibiotics, but this really describes a mechanism of how that might happen," study co-author Ewan Harrison, a researcher at the University of Cambridge and the Wellcome Sanger Institute in the U.K., told Live Science.

“我們之前知道耐藥基因在人類使用抗生素之前就進入了病原體基因組，但現(xiàn)在確實描述了一種可能的發(fā)生機制。”該研究的合著者、劍橋大學(xué)和威爾康桑格研究所的研究員伊萬·哈里森說。

MRSA is a strain of staph bacteria that resists antibiotics and is therefore harder to treat if it gets into the body of humans or livestock and causes disease. The researchers investigated mecC-MRSA, a relatively rare form of the superbug that's responsible for about 1 in 200 human MRSA infections, according to a statement released by the University of Cambridge.

MRSA 是一種抗抗生素的葡萄球菌菌株，因此如果它進入人類或牲畜的身體并引起疾病，則更難治療。根據(jù)劍橋大學(xué)發(fā)布的一份聲明，研究人員調(diào)查了 mecC-MRSA，一種相對罕見的超級細菌，每200例人類 MRSA 感染中就有1例會感染這種細菌。

The mecC-MRSA was discovered in 2011 and was thought to have emerged in cows given large amounts of antibiotics. However, previous research has also found that up to 60 percent of European hedgehogs carry it. The hedgehogs' fungus, Trichophyton erinacei, creates its own penicillin antibiotics naturally to fight off bacteria.

mecC-MRSA于2011年被發(fā)現(xiàn)，并被認為是在服用大量抗生素的奶牛身上出現(xiàn)的。然而，此前的研究也發(fā)現(xiàn)，高達60%的歐洲刺猬攜帶這種病毒。刺猬的真菌，毛癬菌，會創(chuàng)造出自己的青霉素抗生素來對抗細菌。

Harrison was part of an international research team that sequenced genomes of the parasitic fungus on the hedgehogs and found the genes responsible for producing the penicillin antibiotics that kill staph bacteria.

哈里森是一個國際研究小組的成員，該小組對刺猬身上的寄生真菌進行了基因組測序，并發(fā)現(xiàn)了產(chǎn)生殺死葡萄球菌的青霉素抗生素的基因。

They then sequenced the bacteria and dated the penicillin-resistant genes by measuring the number of certain mutations in the genome that are known to occur at a fixed rate each year and counting backward, according to Harrison.

根據(jù)哈里森的說法，他們隨后對細菌進行測序，并通過測量基因組中已知每年以固定速率發(fā)生的某些突變的數(shù)量，然后倒推出青霉素耐藥基因的年代。

They found that the bacteria had resistance to methicillin, a form of penicillin, in the 1800s, long before the clinical use of penicillin began in the 1940s.

早在19世紀(jì)，他們就發(fā)現(xiàn)這種細菌對青霉素的一種形式甲氧西林具有耐藥性，而青霉素的臨床應(yīng)用早在20世紀(jì)40年代就開始了。

The researchers think this type of MRSA probably first evolved in hedgehogs, though they aren't sure how mecC-MRSA crossed into humans.

研究人員認為這種耐甲氧西林金黃色葡萄球菌可能首先在刺猬身上進化，盡管他們不確定mecC-MRSA是如何進入人類體內(nèi)的。

"We know that these resistance genes exist in the soil and soil bacteria, and animals like hedgehogs and other wildlife obviously have much more contact with soil on a day-to-day basis than most of us do," Harrison said.

“我們知道這些抗性基因存在于土壤和土壤細菌中，刺猬和其他野生動物與土壤的日常接觸顯然比我們大多數(shù)人都要多。”哈里森說。

The superbug could have jumped to humans through direct contact with hedgehogs, the authors said. Harrison stressed, however, that people shouldn't fear hedgehogs for this reason.

作者說，這種超級細菌可能通過與刺猬的直接接觸而跳到人類身上。然而，哈里森強調(diào)，人們不應(yīng)該因為這個原因害怕刺猬。

"I don't think hedgehogs are a risk," Harrison said. "I think that's important to get across." The mecC-MRSA is also found in livestock, so these animals, or another unidentified animal, may have been intermediaries.

“我不認為刺猬是一種風(fēng)險，”哈里森說，“認清這一點很重要。” mecC-MRSA 也存在于牲畜中，因此這些動物或其他身份不明的動物可能是中間媒介。

"It just shows evolutionary processes in nature can select for antibiotic resistance and that can end up in a human pathogen," Harrison said.

“它只是表明自然界的進化過程可以選擇抗生素耐藥性，而這最終可能會導(dǎo)致侵害人類的耐藥病原體出現(xiàn)。”哈里森說。

The findings were published Wednesday (Jan. 5) in the journal Nature.

這項研究結(jié)果發(fā)表在周三(1月5日)的《自然》雜志上。