摘要
对菌血症患者血培养中分离的１３８株大肠杆菌（Ｅ．ｃｏｌｉ）检测发现，其中１３株具有Ｒ１和Ｒ４两种核心型。这些Ｅ．ｃｏｌｉ抗原制剂对蛋白酶的消化溶解作用抵抗；对高碘酸作用敏感；用重组杀菌／渗透增强蛋白（ｒ－ＢＰＩ）和克隆２０对其类脂Ａ和内核心ｋｄｏ－庚糖进行封闭后，不影响Ｒ１和Ｒ４抗血清对该种细菌抗原制剂的高反应性。表明，由Ｒ１和Ｒ４抗血清识别结合的抗原成分不是细菌蛋白或多肽，也不是类脂Ａ和内核心ｋｄｏ－庚糖，而是决定细菌核心型的外核心己糖抗原。这是一种文献中尚未报道过的新颖的具有混合脂多糖核心型（Ｒ１Ｒ４）的大肠杆菌。
The specificity of monoclonal antibodies for E. coli LPS-core type was comfirmed ,but monoclonal antibodies specific for R_4 or K_(12) core types were not available. Polyclonal antiseria (Pabs) which made by immunization with rought mutants of E. coli to the rabbits were made monospecific for a given E. coli LPS-core type by absorbtion. We decided that a tentative core type would be assigned to a bacterial strain if the OD obtained with one of the five absorbed Pabs (anti-R_1-R_4 and anti-K_(12)) was at least twice that of the others. According to the standard, Pabs and monoclonal antibodies yielded identical outcomes concering the core type assigned (only R_1, R_2 and R_3 core types). We discovered a novel core type, expressing both the R_1 and R_4 immunospecificity in the E. coli strains isolated from bacteremic patients (13strains/138 strains). They were resistant to proteolytic digestion and sensitive to periodate.After blocking the lipid A and inner core (kdo-heptose) of the E. coli strains by r-BPI and clone 20 respectively. The reactivity of the both anti-R_1 and anti-R_4 Pabs with the E. coli strains was the same as before, it was indicated that the antigens which were recongnized and combined by anti-R1 and anti-R4 Pabs were neither proteins/peptide nor lipid A and inner core(kdo-heptose). It should be outer core hexose antigens. We therefore assigned the R_1R_4 mixed core type to these strains, a core type not yet described in the literature.
