Demonstration of Streptococcus mutans with a cell wall polysaccharide specific to a new serotype, k, in the human oral cavity
Demonstration of Streptococcus mutans with a cell wall polysaccharide specific to a new serotype, k, in the human oral cavity
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DOI：
10.1128/jcm.42.1.198-202.2004
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发表时间：
2004-01-01
影响因子：
9.4
通讯作者：
Ooshima, T
中科院分区：
文献类型：
--
作者：
Nakano, K;Nomura, R;Ooshima, T
感染性心内膜炎患者的血液中偶尔会分离到变形链球菌，但其侵袭和存活机制尚不清楚。从菌血症或感染性心内膜炎患者分离的四株血中有两株(菌株TW295和TW871)经免疫扩散试验不能进行血清学分型，这是由于缺乏变形链球菌血清型特异性多糖抗原的葡萄糖侧链所致。免疫扩散分析显示，来自100名受试者的100株分离物中有2株呈阳性反应，而对来自50名受试者的2500株分离物的进一步分析显示，来自同一受试者的所有50株分离物都不与抗c、-e和-f抗血清反应，尽管它们与抗TW295和-TW871抗血清反应。口腔分离株表现出与变形链球菌参考菌株MT8148相似的生物学特性，包括高水平的蔗糖依赖粘附性和细胞疏水性，以及葡萄糖转移酶和蛋白抗原PA的表达。通过插入失活突变株MT8148的GluA基因构建了一株葡萄糖侧链缺陷突变株，该突变株的生物学特性与k型变形链球菌相似。血清型口腔分离株对吞噬作用的敏感性较低，而菌株MT8148的GluA失活突变株和血液分离株对吞噬作用的敏感性也较低。这些结果表明，变形链球菌k型菌株存在于人类口腔中，由于其对吞噬作用的敏感性较低，可能能够在血液中存活更长时间。
Streptococcus mutans organisms are occasionally isolated from the blood of patients with infective endocarditis, though the mechanisms of invasion and survival remain to be elucidated. Two of four blood isolates from patients with bacteremia or infective endocarditis (strains TW295 and TW871) were serologically untypeable by inummodiffusion testing, which was due to a lack of the glucose side chain of the serotype-specific polysaccharide antigen of S. mutans. Immunodiffusion analyses using antisera against these strains demonstrated that 2 of 100 isolates from 100 subjects showed a positive reaction, while further analysis of 2,500 isolates from 50 subjects revealed that all 50 isolates from a single subject were not reactive with anti-c, -e, and -f antisera, though they were reactive with anti-TW295 and -TW871 antisera. The oral isolates showed biological properties similar to those of the reference S. mutans strain MT8148, including high levels of sucrose-dependent adhesion and cellular hydrophobicity, along with expression of glucosyltransferases and a protein antigen, PA. We designated these organisms serotype k. A glucose side chain-defective mutant strain was then constructed by insertional inactivation of the gluA gene of strain MT8148, which showed biological properties similar to those of serotype k of S. mutans. Serotype k oral isolates were less susceptible to phagocytosis, as were the gluA-inactivated mutant of strain MT8148 and blood isolates. These results indicate that S. mutans serotype k strains are present in the oral cavity in humans and may be able to survive longer in blood owing to their low susceptibility to phagocytosis.