Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 14, 2005
Publication Date: August 1, 2005
Citation: Durso, L.M., Bono, J.L., Keen, J.E. 2005. Molecular serotyping of Escherichia coli O26:H11. Applied and Environmental Microbiology. 71(8):4941-4944. Interpretive Summary: Serotyping is the foundation of Escherichia coli diagnostics; however, few labs have this capacity. We developed a molecular serotyping protocol for E. coli O26:H1 that targets, genetically, the same antigens used in traditional serotyping. It correctly serotypes E. coli O26 and H11 strains untypable by traditional methods, affording primary laboratories serotyping capabilities. E. coli serotype O26:H11 is commonly grouped with the shiga toxin-producing E. coli (STEC), of which E. coli O157:H7 is the most prominent member. E. coli O26 is the single most frequently isolated non-O157 STEC associated with human clinical illness. It is associated with human clinical disease worldwide, and has been isolated exclusively from humans, cattle, and cattle products. Serotyping of antigens associated with the body (O) and flagella (H) of E. coli is essential for accurate diagnostics and surveillance of pathogenic strains. Conventional serotyping is the gold standard for E. coli identification, but it involves costly, animal-derived reagents and highly trained personnel, thus, limiting its use to reference laboratories. We developed a molecular serotyping procedure that uses multiplex PCR that targets, genetically, the same O and H antigens used in conventional serotyping, and that can be easily performed in most laboratories. PRC primers were designed based on sequencing of O and H antigen genes from multiple E. coli O26 and H11 strains. The assay sensitivity and specificity were 100% based on testing of 322 diverse E. coli and 22 non-E. coli strains. The O26 and H11 status of 42 E. coli tested blindly by the molecular serotyping assay agreed with conventional serotypes. Additionally, molecular serotyping was able to provide information on 45 of 46 strains that were H-untypable by conventional serotyping.
Technical Abstract: Serotyping is the foundation of Escherichia coli diagnostics; however, few labs have this capacity. We developed a molecular serotyping protocol that targets, genetically, the same somatic and flagellar antigens of E. coli O26:H11 used in traditional serotyping. It correctly serotypes strains untypable by traditional methods, affording primary laboratories serotyping capabilities.