To provide an antibody directed against E. coli (in particular MDR strains) with improved specificity to be used for the prevention or therapy of E. coli infections caused by Lipopolysaccharide (LPS) O25b carrying strains and to provide means and methods that are capable of diagnosing E. coli bacteria (such as MDR strains) in a rapid and reliable manner.SOLUTION: The invention refers to an isolated antibody that specifically binds to O25b antigen of E. coli strains comprising at least an antibody heavy chain variable region (VH), which comprises any of the CDR1 to CDR3 sequences having specific amino acid sequences or functionally active CDR variants of any of them.SELECTED DRAWING: None【課題】リポ多糖（ＬＰＳ）Ｏ２５ｂを有する菌株によって引き起こされる大腸菌感染症の防止または治療のために使用される改善された特異性を有する、大腸菌（特にＭＤＲ菌株）に対する抗体、及び大腸菌細菌（例えば、ＭＤＲ菌株など）を迅速かつ確実な様式で診断することができる手段および方法の提供。【解決手段】特定のアミノ酸配列を有すＣＤＲ１配列～ＣＤＲ３配列、あるいはそれらの機能的に活性なＣＤＲ変化体のいずれかを含む抗体重鎖可変領域（ＶＨ）を少なくとも含む、大腸菌菌株のＯ２５ｂ抗原に特異的に結合する単離された抗体。【選択図】なし
