沙門氏菌侵入人體細(xì)胞的電鏡圖(Credit: Rocky Mountain Laboratories, NIAID, NIH)
近日,，來(lái)自加州大學(xué)圣芭芭拉分校等處的研究者發(fā)明了一種檢測(cè)高毒力沙門氏菌的方法,，這為將來(lái)阻止食品受沙門氏菌感染提供了一定的檢測(cè)方法,。研究者相關(guān)的研究成果刊登在了近日的國(guó)際雜志PLoS Pathogen上,。沙門氏菌是一種常見的可以引起院內(nèi)感染以及食品中毒的常見致病菌,，近幾年因?yàn)樯抽T氏菌的感染給人類的健康影響和帶來(lái)的經(jīng)歷負(fù)擔(dān)越來(lái)越大,。為此,，研究者對(duì)高毒力沙門氏菌菌株進(jìn)行研究,，旨在找到一種檢測(cè)方法來(lái)抵御這種細(xì)菌對(duì)食品的危害以及給畜牧業(yè)帶來(lái)的風(fēng)險(xiǎn)。
來(lái)自芭芭拉分校以及悉尼大學(xué)的研究者組成了一個(gè)大的研究團(tuán)隊(duì)來(lái)進(jìn)行高毒力沙門氏菌的研究,，這些細(xì)菌分離自牲畜身上,，而且用疫苗完全無(wú)效。細(xì)菌的行為就像是木馬一樣,，只是在開始感染之后才展現(xiàn)其強(qiáng)大的致病武器,，研究者Heithoff表示，這些菌株可持續(xù)感染,，而且長(zhǎng)達(dá)5年,，它們?cè)诟腥酒陂g可以不斷變化來(lái)引起不同形式的感染。研究者發(fā)明出了一種檢測(cè)方法,，可以快速檢測(cè)并且從很多不同毒力的菌株中識(shí)別出高毒力的菌株,。人們通常通過(guò)食用被污染的牛肉、雞肉和雞蛋引起沙門氏菌食物中毒,，而且感染沙門氏菌的牲畜所排出的糞便也會(huì)污染蔬菜以及水果,，這無(wú)疑是一種健康隱患。因?yàn)樯抽T氏菌的感染或者污染導(dǎo)致美國(guó)每年損失146億美元,。
高毒力的沙門氏菌對(duì)人類和動(dòng)物的健康都構(gòu)成威脅,，必須引起研究者的高度重視，目前,，研究者已經(jīng)意識(shí)到了這種細(xì)菌引起的問題了,，而且已經(jīng)采取措施去制止這種細(xì)菌所引起的感染和疾病了。（生物谷：T.Shen編譯）
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doi:10.1371/journal.ppat.1002647
PMC:
PMID:
Intraspecies Variation in the Emergence of Hyperinfectious Bacterial Strains in Nature
Douglas M. Heithoff1#, William R. Shimp1#, John K. House2, Yi Xie3, Bart C. Weimer3, Robert L. Sinsheimer1, Michael J. Mahan1*
Salmonella is a principal health concern because of its endemic prevalence in food and water supplies, the rise in incidence of multi-drug resistant strains, and the emergence of new strains associated with increased disease severity. Insights into pathogen emergence have come from animal-passage studies wherein virulence is often increased during infection. However, these studies did not address the prospect that a select subset of strains undergo a pronounced increase in virulence during the infective process- a prospect that has significant implications for human and animal health. Our findings indicate that the capacity to become hypervirulent (100-fold decreased LD50) was much more evident in certain S. enterica strains than others. Hyperinfectious salmonellae were among the most virulent of this species; restricted to certain serotypes; and more capable of killing vaccinated animals. Such strains exhibited rapid (and rapidly reversible) switching to a less-virulent state accompanied by more competitive growth ex vivo that may contribute to maintenance in nature. The hypervirulent phenotype was associated with increased microbial pathogenicity (colonization; cytotoxin production; cytocidal activity), coupled with an altered innate immune cytokine response within infected cells (IFN-β; IL-1β; IL-6; IL-10). Gene expression analysis revealed that hyperinfectious strains display altered transcription of genes within the PhoP/PhoQ, PhoR/PhoB and ArgR regulons, conferring changes in the expression of classical virulence functions (e.g., SPI-1; SPI-2 effectors) and those involved in cellular physiology/metabolism (nutrient/acid stress). As hyperinfectious strains pose a potential risk to human and animal health, efforts toward mitigation of these potential food-borne contaminants may avert negative public health impacts and industry-associated losses.
