Fig Source：Colonies of Streptococcus tigurinus on sheep blood agar plate. (Credit: Andrea Zbinden)
近日，來自瑞士蘇黎世大學(xué)的研究者在口腔中發(fā)現(xiàn)了一種常見細(xì)菌,，這種細(xì)菌如果進(jìn)入血液有可能導(dǎo)致嚴(yán)重的疾病，這項(xiàng)研究成果刊登在了近日的國(guó)際雜志The International Journal of Systematic and Evolutionary Microbiology上,，這項(xiàng)新的研究發(fā)現(xiàn)將有助于科學(xué)家研究這種細(xì)菌是如何致病的，并且可以評(píng)估這種細(xì)菌的致病風(fēng)險(xiǎn),。
研究者發(fā)現(xiàn)的這種細(xì)菌命名為Streptococcus tigurinus(S.tigurinus,，鏈球菌屬的某種細(xì)菌)，S.tigurinus是從心內(nèi)膜炎,、腦膜炎,、脊椎關(guān)節(jié)炎病人的血液中分離出來的，和鏈球菌屬的其它細(xì)菌有很高的相似性,，都可以在口腔中繁殖,，常見的牙齦出血會(huì)給這種細(xì)菌進(jìn)入血液進(jìn)而造成嚴(yán)重的感染提供便利的途徑。 領(lǐng)導(dǎo)此項(xiàng)研究的研究者Andrea Zbinden博士表示:“S.tigurinus的識(shí)別對(duì)于臨床上治療非常重要,，精確地識(shí)別,、研究該細(xì)菌對(duì)于追蹤該細(xì)菌的分布、以及感染機(jī)制,、途徑都非常有必要,，而且可以為我們臨床上尋扎合適的治療藥物進(jìn)行治療提供一定的線索。
研究者又表示,，S.tigurinus的發(fā)現(xiàn)并不可怕,，這種細(xì)菌的致病風(fēng)險(xiǎn)是可以估計(jì)的，而且有能力引起嚴(yán)重的感染疾病,，下一步,，我們研究的重點(diǎn)是解釋S.tigurinus在口腔中為什么是如此普遍，以及S.tigurinus的致病風(fēng)險(xiǎn),，免疫抑制,、異常的心臟瓣膜感染以及慢性感染等都很有可能是因?yàn)镾.tigurinus進(jìn)入血液產(chǎn)生的感染所引起的。然而S.tigurinus特殊的感染因子（或感染機(jī)制）有待于進(jìn)一步研究才能夠解釋,。（生物谷：T.Shen編譯）
doi:10.1099/ijs.0.038299-0
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PMID:
Streptococcus tigurinus sp. nov., isolated from blood of patients with endocarditis, meningitis and spondylodiscitis
Andrea Zbinden1,5, Nicolas J. Mueller2, Philip E. Tarr3, Cathrin Spröer4, Peter M. Keller1 and Guido V. Bloemberg1
Four Gram-stain-positive, catalase-negative, coccus-shaped bacterial strains were isolated from multiple blood cultures of patients with endocarditis, meningitis and spondylodiscitis. The isolates were tentatively identified as viridans streptococcal species based on phenotypic characteristics. Comparative 16S rRNA gene sequencing studies showed that the organisms were members of the Streptococcus mitis group but did not correspond to any recognized species. The nearest phylogenetic relative was Streptococcus mitis ATCC 49456T with 98.6% sequence similarity. The representative strain AZ_3aT showed similarity values of less than 96.8%, 97.6%, 94.5% and 95.5% to the phylogenetically most closely related species by recA, rpoB, sodA and groEL gene sequence analysis, respectively. DNA-DNA hybridization analyses showed a low reassociation value of 32.2% between strain AZ_3aT and S. mitis DSM 12643T. Reassociation values with other S. mitis group species ranged from 27.3% to 49.7%. The G+C content of the DNA is 40.0 mol%. Based on our biochemical and molecular analyses, the novel isolates represent a new species, for which the name Streptococcus tigurinus sp. nov. is proposed. The type strain is AZ_3aT( =CCOS 600T =DSM 24864T).
