title: Molecular Differentiation ofShigellaSpp. from EnteroinvasiveE. Coli.
abstract: A real-time polymerase chain reaction (PCR) assay, amplifying the genes encoding lactose permease(lacY)and invasion plasmid antigen H(ipaH), was run on 121 isolates phenotypically classified asShigellaspp., enteroinvasiveEscherichia coli(EIEC), or EIEC O nontypable (ONT). The results were compared with data from a genericE. colimultiple-locus variable-number of tandem repeat analysis (MLVA) and aShigellaMLVA. The real-time PCR verified allShigellaspp. (n= 53) asShigella(lacYnegative) and all EIEC O121 (n= 15) and EIEC O124 (n= 2) as EIEC (lacYpositive). However, the real-time PCR typed EIEC O164 as either EIEC (n= 2) orShigella(n= 2) and, thus, was not suited for classifying this group of isolates. Interestingly, the majority (42/47, 89.4%) of the EIEC ONT were classified asShigella(lacYnegative) by the real-time PCR, and in nearly all cases, (92.9%, 39/42) data from both MLVA assays supported these findings. Overall, in 94.7% (114/121) of the isolates, the results from the real-time PCR were substantiated by the results from the MLVA assays. In conclusion, the real-time PCR assay was fast and accurate in differentiatingShigellaspp. from EIEC, with the exception of the EIEC O164 group. This molecular assay was particularly pragmatic for the challenging EIEC ONT group.
authors.affiliation: Department of Foodborne Infections, The Norwegian Institute of Public Health , Oslo, Norway.
authors.forename: I
authors.initials: I
authors.lastname: Løbersli
authors.affiliation: Department of Foodborne Infections, The Norwegian Institute of Public Health , Oslo, Norway.
authors.forename: A L
authors.initials: AL
authors.lastname: Wester
authors.affiliation: Department of Foodborne Infections, The Norwegian Institute of Public Health , Oslo, Norway.
authors.forename: Å
authors.initials: Å
authors.lastname: Kristiansen
authors.affiliation: Department of Foodborne Infections, The Norwegian Institute of Public Health , Oslo, Norway.
authors.forename: L T
authors.initials: LT
authors.lastname: Brandal
keywords: EIEC; MLVA; Shigella; molecular differentiation; real-time PCR