Enterococcal surface protein contributes to persistence in the host but is not a target of opsonic and protective antibodies in Enterococcus faecium infection
Enterococcal surface protein contributes to persistence in the host but is not a target of opsonic and protective antibodies in Enterococcus faecium infection
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DOI：
10.1099/jmm.0.020578-0
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发表时间：
2010-09-01
影响因子：
3
通讯作者：
Huebner, J.
中科院分区：
文献类型：
--
作者：
Sava, I. G.;Heikens, E.;Huebner, J.
肠球菌是一种重要的院内病原菌，具有多种内在耐药和获得性耐药。过去，大多数感染是由粪肠球菌引起的；然而，近年来观察到粪肠球菌临床分离株的增加。肠球菌表面蛋白（Esp）在大多数粪肠杆菌临床分离株的表面表达，并已被证明参与生物膜的形成。本研究在小鼠菌血症模型中比较了E. faecium E1162及其先前创建的esp基因插入-缺失突变E. faecium E1162 Delta esp。研究了抗esp血清在体外介导调理噬细胞杀灭E1162的能力和对粪肠杆菌血症的保护作用。与野生型菌株相比，esp的失活降低了粪肠杆菌的毒力，感染该突变株的动物肾脏中恢复的细菌数量减少（P=0.035）。重组n端Esp蛋白兔多克隆血清被动免疫小鼠对粪肠杆菌血症无保护作用（P < 0.05）。相比之下，用粪肠杆菌脂磷胆酸（LTA）多克隆抗血清被动免疫小鼠血液中粪肠杆菌E1162的数量低于用正常兔血清免疫小鼠。这些结果表明Esp有助于粪肠杆菌在宿主体内的持久性。然而，与LTA相比，在小鼠菌血症中，Esp似乎不是E. faecium菌株E1162保护性抗体的靶点。
Enterococci are important nosocomial pathogens with multiple intrinsic and acquired resistances to antibiotics. In the past, the majority of infections were caused by Enterococcus faecalis; however, an increase in Enterococcus faecium clinical isolates has been observed in recent years. The enterococcal surface protein (Esp) is expressed on the surface of most E. faecium clinical isolates and has been shown to be involved in biofilm formation. Here, E. faecium E1162 and its previously created insertion-deletion mutant of the esp gene, E. faecium E1162 Delta esp, were compared in a mouse bacteraemia model. Anti-Esp serum was tested for its capacity to mediate opsonophagocytic killing of E1162 in vitro and to protect against E. faecium bacteraemia. The inactivation of esp attenuated E. faecium virulence with reduced numbers of bacteria recovered from the kidneys in animals infected with the mutant compared to the wild-type strain (P=0.035). Passive immunization with rabbit polyclonal serum raised against the recombinant N-terminal Esp protein did not protect mice against E. faecium bacteraemia (P>0.05). In contrast, mice passively immunized with polyclonal antiserum raised against lipoteichoic acid (LTA) from E. faecalis had lower numbers of E. faecium E1162 in the blood compared to mice immunized with normal rabbit serum. These results suggest that Esp contributes to E. faecium persistence in the host. However, in contrast to LTA, Esp does not seem to be a target for protective antibodies in E. faecium strain E1162 in mouse bacteraemia.