研究揭示人体正常菌群致病原因
路透社纽约健康消息 近期《自然》杂志上一项研究报告揭示了为什么广泛存在人体的正常菌群金黄色葡萄球菌会在某些人体内引起威胁生命的疾病，而且难以治疗。对大多数人来说，这种普通菌群还是安全无害的。
金黄色葡萄球菌是一种最常引起医院内严重感染的致病菌，会导致肺炎和脑膜炎。该菌通常也存在于健康人的皮肤表面和鼻道里，大约60%的人在一生中某一段时期鼻腔里都曾经携带有这种球菌，但一般不会引起任何症状。研究人员指出，也许是那些保证金黄色葡萄球菌在人体内正常生长不致病的因素有可能造成潜在的感染危险。
美国牛津大学的研究人员尼古拉斯·得博士和他的同事们对61名严重感染金黄色葡萄球菌的患者，179名健康个体和94名医院内感染者的鼻内携带的金黄色葡萄球菌进行了采样对比分析。结果发现，金黄色葡萄球菌的某些基因株与疾病的发生有着不成比例的关系。但是，在健康人体内也发现这种菌株。
研究人员推测，也许存在着某些因素使金黄色葡萄球菌既能不致病，也能产生剧毒致病。虽然具体的细节还不十分清楚，但尼古拉斯·得博士认为，是金黄色葡萄球菌的某些跟新陈代谢有关的毒素或基因使这种球菌比体内其他正常菌群繁殖快，导致人体内菌群失调从而致病。而且，这些因素同样也可以帮助金黄色葡萄球菌逃避机体的防御系统而进入血液循环中。
, 百拇医药
报告显示，为了适应环境并且更好地生存下去，金黄色葡萄球菌在进化过程中已经变得有足够的感染能力，能在人群中传播开去，但又不至于毒性太强而杀死太多的宿主。尼古拉斯·得博士用“生物进化适应理论”来解释为什么某些金黄色葡萄球菌菌株会致病而另外的则不会。他说，由于这些细菌具有强大的多种多样的繁殖能力，因此在生态学上比其他细菌更适合生存。这种巨大的无性生殖使细菌的分布几乎是全球性的，正是这些原因使它们更适合生存的因素也许同样使它们更容易引起疾病。
哈佛大学公共卫生系一位流行病学专家说，这项研究对以后的工作具有令人兴奋的启示作用。他在一篇评论中写道：“当引起疾病并不是细菌生命循环过程中的必需或基本的部份时，为什么细菌还是会引起疾病，该研究揭示了这一谜底。”
Study suggests why good bacteria sometimes go bad
NEW YORK(Reuters Health) - New research is shedding light on why a common group of bacteria causes life-threatening illnesses and outwits treatment in some people, yet lives happily and harmlessly in most individuals.
, 百拇医药
In the April 6th issue of Science, investigators report that some factors that make Staphylococcus aureus (S. aureus) thrive and live peacefully in humans also make them potent infectious agents.
S. aureus can cause pneumonia and meningitis, and the bacteria are among the most common causes of serious infections that patients acquire while hospitalized. However, they often can be found growing on the skin or in the nasal passages of healthy people, causing no problems whatsoever. About 60% of people in the population carry the bacteria in their nose at one time or another, and it is usually symptomless.
, 百拇医药
In a study analyzing S. aureus taken from the noses of ill and healthy individuals, Dr. Nicolas P. J. Day and his colleagues compared 61 samples of bacteria collected from patients with serious infection with 179 samples collected from healthy individuals and 94 samples from patients who picked up an infection while in the hospital.
The researchers found that certain genetic strains of S. aureus were disproportionately responsible for disease cases. Yet those same strains were also common among healthy people. This suggests that some of the factors that make S. aureus so common also make it extremely virulent in certain cases.
, 百拇医药
While the specifics are not yet known, Day suggests that certain toxins or genes related to metabolism may help S. aureus "beat other bugs in the nose" in order to thrive. These factors may also "almost coincidentally" help S. aureus evade the body‘s defenses and get into the bloodstream.
The report suggests that, in evolutionary terms, these bacteria have become "fit" by being infectious enough to spread among humans, yet not virulent enough to kill off too many of its hosts.
, 百拇医药
"If you can double your population faster than your neighbor due to an efficient metabolism, that may also help you in terms of virulence," Day, a researcher at University of Oxford, UK, told Reuters Health.
Day said it is not clear why some strains of bacteria become virulent while others do not, but he suggested a theory of "evolution of ecological fitness."
"Out of the great and varied...bacterial population, bacteria occasionally arise which are ecologically fitter than others. This leads to their massive clonal expansion, probably worldwide," he said. "It so happens that these bugs are better at causing disease than others because of whatever is making them ecologically fit."
, 百拇医药
The study has "exciting implications for future research," Dr. Marc Lipsitch, an epidemiologist from Harvard School of Public Health in Boston, Massachusetts, notes in an accompanying editorial.
"Their findings suggest an answer to the riddle of why S. aureus has evolved mechanisms for causing disease when disease is not a necessary or even a common part of its life cycle," Lipsitch writes., 百拇医药
金黄色葡萄球菌是一种最常引起医院内严重感染的致病菌，会导致肺炎和脑膜炎。该菌通常也存在于健康人的皮肤表面和鼻道里，大约60%的人在一生中某一段时期鼻腔里都曾经携带有这种球菌，但一般不会引起任何症状。研究人员指出，也许是那些保证金黄色葡萄球菌在人体内正常生长不致病的因素有可能造成潜在的感染危险。
美国牛津大学的研究人员尼古拉斯·得博士和他的同事们对61名严重感染金黄色葡萄球菌的患者，179名健康个体和94名医院内感染者的鼻内携带的金黄色葡萄球菌进行了采样对比分析。结果发现，金黄色葡萄球菌的某些基因株与疾病的发生有着不成比例的关系。但是，在健康人体内也发现这种菌株。
研究人员推测，也许存在着某些因素使金黄色葡萄球菌既能不致病，也能产生剧毒致病。虽然具体的细节还不十分清楚，但尼古拉斯·得博士认为，是金黄色葡萄球菌的某些跟新陈代谢有关的毒素或基因使这种球菌比体内其他正常菌群繁殖快，导致人体内菌群失调从而致病。而且，这些因素同样也可以帮助金黄色葡萄球菌逃避机体的防御系统而进入血液循环中。
, 百拇医药
报告显示，为了适应环境并且更好地生存下去，金黄色葡萄球菌在进化过程中已经变得有足够的感染能力，能在人群中传播开去，但又不至于毒性太强而杀死太多的宿主。尼古拉斯·得博士用“生物进化适应理论”来解释为什么某些金黄色葡萄球菌菌株会致病而另外的则不会。他说，由于这些细菌具有强大的多种多样的繁殖能力，因此在生态学上比其他细菌更适合生存。这种巨大的无性生殖使细菌的分布几乎是全球性的，正是这些原因使它们更适合生存的因素也许同样使它们更容易引起疾病。
哈佛大学公共卫生系一位流行病学专家说，这项研究对以后的工作具有令人兴奋的启示作用。他在一篇评论中写道：“当引起疾病并不是细菌生命循环过程中的必需或基本的部份时，为什么细菌还是会引起疾病，该研究揭示了这一谜底。”
Study suggests why good bacteria sometimes go bad
NEW YORK(Reuters Health) - New research is shedding light on why a common group of bacteria causes life-threatening illnesses and outwits treatment in some people, yet lives happily and harmlessly in most individuals.
, 百拇医药
In the April 6th issue of Science, investigators report that some factors that make Staphylococcus aureus (S. aureus) thrive and live peacefully in humans also make them potent infectious agents.
S. aureus can cause pneumonia and meningitis, and the bacteria are among the most common causes of serious infections that patients acquire while hospitalized. However, they often can be found growing on the skin or in the nasal passages of healthy people, causing no problems whatsoever. About 60% of people in the population carry the bacteria in their nose at one time or another, and it is usually symptomless.
, 百拇医药
In a study analyzing S. aureus taken from the noses of ill and healthy individuals, Dr. Nicolas P. J. Day and his colleagues compared 61 samples of bacteria collected from patients with serious infection with 179 samples collected from healthy individuals and 94 samples from patients who picked up an infection while in the hospital.
The researchers found that certain genetic strains of S. aureus were disproportionately responsible for disease cases. Yet those same strains were also common among healthy people. This suggests that some of the factors that make S. aureus so common also make it extremely virulent in certain cases.
, 百拇医药
While the specifics are not yet known, Day suggests that certain toxins or genes related to metabolism may help S. aureus "beat other bugs in the nose" in order to thrive. These factors may also "almost coincidentally" help S. aureus evade the body‘s defenses and get into the bloodstream.
The report suggests that, in evolutionary terms, these bacteria have become "fit" by being infectious enough to spread among humans, yet not virulent enough to kill off too many of its hosts.
, 百拇医药
"If you can double your population faster than your neighbor due to an efficient metabolism, that may also help you in terms of virulence," Day, a researcher at University of Oxford, UK, told Reuters Health.
Day said it is not clear why some strains of bacteria become virulent while others do not, but he suggested a theory of "evolution of ecological fitness."
"Out of the great and varied...bacterial population, bacteria occasionally arise which are ecologically fitter than others. This leads to their massive clonal expansion, probably worldwide," he said. "It so happens that these bugs are better at causing disease than others because of whatever is making them ecologically fit."
, 百拇医药
The study has "exciting implications for future research," Dr. Marc Lipsitch, an epidemiologist from Harvard School of Public Health in Boston, Massachusetts, notes in an accompanying editorial.
"Their findings suggest an answer to the riddle of why S. aureus has evolved mechanisms for causing disease when disease is not a necessary or even a common part of its life cycle," Lipsitch writes., 百拇医药