Perhaps the chief poster child of antibiotic¹ resistance is methicillin-resistant Staphylococcus aureus, or MRSA. The bacterium² is impervious³ to a suite⁴ of antibiotics⁵, and can cause blood infections, pneumonia…even death.

也许抗生素耐药性的主要代表就是耐甲氧西林金黄色葡萄球菌（MRSA）这种细菌，它不受系列抗生素的影响，还能引起感染、肺炎甚至死亡。

And you'd assume that it developed its namesake resistance to methicillin…by being exposed to methicillin.

你会认为它之所以有耐药性，是因为它暴露于甲氧西林中。

But that doesn't seem to be the case. Instead, the culprit for resistance appears to be an earlier, and chemically related antibiotic: penicillin⁶.

但并不是这样的。相反，耐药性的罪魁祸首似乎是早期的，与化学相关的抗生素：盘尼西林。

"We think it's a very early use of penicillin that forced the strains to pick up these mechanisms⁷." Matthew Holden, a molecular⁸ microbiologist at the University of Saint Andrews in Scotland.

苏格兰圣安德鲁斯大学的分子微生物学家马修·霍尔登表示：“我们认为是早期使用青霉素，使菌株提取了这些机制。”

Holden and his team analyzed⁹ the genomes of freeze-dried strains of MRSA bacteria, from the 1960s through the '80s.

霍尔登和他的团队分析了20世纪60年代至80年代经过冷冻干燥处理的MRSA细菌基因组。

"In effect what we were doing was sort of genomic archaeology¹⁰, in looking at the genomes, and comparing the variation and using that information to effectively reconstruct the evolutionary¹¹ histories," he said.

他说：“实际上，我们有点像做基因组考古研究。通过比较分析，得出变异基因组并利用这些信息进行有效地重新构建细菌进化史。”

What they found was that the Staph bacteria seem to have acquired the methicillin-resistance gene in the mid-1940s—about 15 years before methicillin even hit the market.

他们发现，葡萄球菌似乎于20世纪40年代中期就有了耐药性的基因--大约在甲氧西林进入市场15年前时候。

And they determined¹² that it was the widespread use of penicillin that led to that adaptation. The results are in the journal Genome Biology.

他们得出结论，正是青霉素的广泛使用才出现了耐药性适应性。这项研究结果发表在《基因生物学》杂志上。

Methicillin was introduced in the U.K. in 1959. Less than a year later, resistance was first reported—resistance that it appears now was already baked into the staph strains.

甲氧西林由英国于1959年引入。不到一年时间，就出现了第一次抗药性的报道--一种似乎现在已经进入了葡萄球菌菌株的耐药性。

Looking ahead, Holden says we'd do well to vigilantly¹³ monitor the genetics of circulating strains—to find out which bugs¹⁴ may be armed to battle our newest antibiotics as soon as they're developed.

霍尔登称，我们要非常谨慎地监控细菌菌株的基因遗传，这样才能查明，在抗生素开发出来之前，有哪些细菌可能会出现抗药性。