人类感染的mrsa菌株源于家畜-凯发k8官网

人类感染的mrsa菌株源于家畜
文章来源:未知 文章作者:enread 发布时间:2013-08-14 07:45 字体: [ ] 
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a strain of bacteria that causes skin and soft tissue infections in humans originally came from cattle, according to a study to be published in mbio®, the online open-access journal of the american society for microbiology. the researchers who conducted the 1 analysis of strains of staphylococcus aureus known as cc97 say these strains developed resistance to methicillin(甲氧西林) after they crossed over into humans around forty years ago. today, methicillin-resistant s. aureus (mrsa) strain cc97 is an emerging human pathogen in europe, north and south america, africa, and asia. the findings highlight the potential for cows to serve as a reservoir for bacteria with the capacity for pandemic(普遍的) spread in humans. the researchers sequenced the genomes of 43 different cc97 2 from humans, cattle, and other animals, and plotted their genetic relationships in a phylogenetic tree. corresponding author ross fitzgerald of the roslin institute and the university of edinburgh in scotland says strains of cc97 found in cows appear to be the ancestors of cc97 strains from humans.
 
"3 strains seemed to occupy deeper parts of the phylogenetic tree -- they were closer to the root than the human strains. this led us to conclude that the strains infecting humans originated in cows and that they had evolved from bovine(牛科动物) to human host jumps," says fitzgerald.
 
although the cc97 strains from animals were quite 4 diverse, the human isolates cluster together in two tight, distinct "clades," or relatedness groups, indicating that s. aureus cc97 in cattle crossed over into humans on two separate occasions. using 5 rates as a 6 clock, the authors 7 that the ancestor of clade a jumped from a bovine host to humans between 1894 and 1977 and clade b made the jump between 1938 and 1966.
 
after they made the jump, the human cc97 strains acquired some new 8, says fitzgerald, thanks to 9 encoded on portable pieces of 10 called mobile genetic elements.
 
"it seems like these elements, such as pathogenicity islands, phages, and plasmids, are important in order for the 11 to adapt to different host species," says fitzgerald. "the reverse is true as well: the bovine strains have their own mobile genetic elements."
 
perhaps the most problematic new 12 the human strains acquired is the ability to resist methicillin, an important 13 for fighting staphylococcal infections. only human strains of cc97 were able to resist the drug, which indicates that the bacteria acquired resistance after they crossed over into humans, presumably through exposure to 14 prescribed for treating human infections.


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1 pgixp     
adj.遗传的,遗传学的
参考例句:
  • it's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
  • each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
2 338356f90b44ba66febab4a4c173b0f7     
v.使隔离( isolate的第三人称单数 );将…剔出(以便看清和单独处理);使(某物质、细胞等)分离;使离析
参考例句:
  • the transformer isolates the transistors with regard to d-c bias voltage. 变压器可在两个晶体管之间隔离直流偏压。 来自辞典例句
  • in regions with certain isolates of trv, spraining is more prominent. 在具有trv某些分离物的地区,坏死是比较显著的。 来自辞典例句
3 ys5zy     
adj.牛的;n.牛
参考例句:
  • he threw off his pack and went into the rush-grass andand munching,like some bovine creature.他丢开包袱,爬到灯心草丛里,像牛似的大咬大嚼起来。
  • he was a gentle,rather bovine man.他是一位文雅而反应迟钝的人。
4 lgixo     
adv.遗传上
参考例句:
  • all the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
  • genetically modified foods have already arrived on american dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物
5 t1pym     
n.变化,变异,转变
参考例句:
  • people who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
  • so far the discussion has centered entirely around mutation in the strict sense.到目前为止,严格来讲,讨论完全集中于围绕突变问题上。
6 me9xh     
adj.分子的;克分子的
参考例句:
  • the research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • for the pressure to become zero, molecular bombardment must cease.当压强趋近于零时,分子的碰撞就停止了。
7 duszmp     
adj.坚定的;有决心的
参考例句:
  • i have determined on going to tibet after graduation.我已决定毕业后去西藏。
  • he determined to view the rooms behind the office.他决定查看一下办公室后面的房间。
8 f7b11037f2050959293aafb493b7653c     
n.能力( capability的名词复数 );可能;容量;[复数]潜在能力
参考例句:
  • he was somewhat pompous and had a high opinion of his own capabilities. 他有点自大,自视甚高。 来自辞典例句
  • some programmers use tabs to break complex product capabilities into smaller chunks. 一些程序员认为,标签可以将复杂的功能分为每个窗格一组简单的功能。 来自about face 3交互设计精髓
9 01914f8eac35d7e14afa065217edd8c0     
n.基因( gene的名词复数 )
参考例句:
  • you have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因,所以能够活得很长。 来自《简明英汉词典》
  • differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪
10 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • dna is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • gene mutations are alterations in the dna code.基因突变是指dna密码的改变。
11 bn7ze     
n.(pl.)bacteria 细菌
参考例句:
  • the bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
  • a bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。
12 jsgzz     
n.能力;才能;(pl)可发展的能力或特性等
参考例句:
  • she has the capability to become a very fine actress.她有潜力成为杰出演员。
  • organizing a whole department is beyond his capability.组织整个部门是他能力以外的事。
13 knjzd     
adj.抗菌的;n.抗生素
参考例句:
  • the doctor said that i should take some antibiotic.医生说我应该服些用抗生素。
  • antibiotic can be used against infection.抗菌素可以用来防止感染。
14 lzgzqt     
n.(用作复数)抗生素;(用作单数)抗生物质的研究;抗生素,抗菌素( antibiotic的名词复数 )
参考例句:
  • the discovery of antibiotics in the 20th century 20世纪抗生素的发现
  • the doctor gave me a prescription for antibiotics. 医生给我开了抗生素。
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