title: Specificity analysis of a novel phage-derived ligand in an enzyme-linked fluorescent assay for the detection of Escherichia coli O157:H7.
abstract: An assay using a phage-derived ligand to capture Escherichia coli O157:H7 prior to antibody detection was evaluated for assay specificity. Analysis of 200 strains showed that the assay was highly specific for the O157 serogroup. It detected all the O157:H7 strains including Shiga toxin-producing O157 nonmotile strains as well as O157 non-H7 strains. In addition, the assay detected various O157:H7 phenotypic variants that are not easily detected by routine analytical methods, as well as a rough strain that did not express O157 antigen and therefore is undetectable serologically. The phage ligand assay showed no cross-reactivity to the other E. coli serotypes. Isolates of Salmonella group N and a few Citrobacter freundii strains that cross-reacted with anti-O157 sera also showed cross-reactivity with the phage ligand. However, other strains that cross-reacted serologically with anti-O157 sera were correctly identified as negative with the phage ligand assay, including several strains of E. coli that nonspecifically autoagglutinate latex reagents.
authors.affiliation: Unité de Microbiologie Alimentaire et Prévisionnelle, Ecole Vétérinaire de Lyon, Lyon, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Rozand
authors.forename: Peter C H
authors.initials: PC
authors.lastname: Feng
mesh_terms: D015373:Bacterial Typing Techniques; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards*; D019453:Escherichia coli O157 / Q000302:isolation & purification* / Q000378:metabolism; D005453:Fluorescence; D005506:Food Contamination / Q000032:analysis*; D008024:Ligands; D012680:Sensitivity and Specificity; D022603:Shiga Toxins / Q000096:biosynthesis*
chemical_list: D008024:Ligands; D022603:Shiga Toxins