title: PCR-based detection and molecular characterization of shiga toxin-producing Escherichia coli strains in a routine microbiology laboratory over 16 years.
abstract: Shiga toxin-producing Escherichia coli (STEC) is a heterogeneous group of bacteria causing disease ranging from asymptomatic carriage and mild infection to hemolytic uremic syndrome (HUS). Here, we describe patients with STEC infection and characterize the STEC strains detected in our laboratory by use of PCR for stx1, stx2, and eae from 1996 through 2011. Patient information was collected from referral forms and from the Norwegian Surveillance System for Communicable Diseases. STEC isolates were characterized with respect to serogroup or serotype, selected potential virulence genes, and multilocus variable-number tandem-repeat analysis (MLVA) genotype. STEC strains were isolated from 138 (1.09%) of 12,651 patients tested. STEC strains of serogroups O26, O103, O121, O145, and O157 were the most frequent. These serogroups, except non-sorbitol-fermenting O157, were also the most frequent among the 11 patients (all ≤5 years old) who developed HUS. Twenty-four STEC strains were classified as being HUS associated based on an epidemiological link to a HUS case, including an MLVA genotype identical to that of the STEC strain. The age of the patient (≤5 years) and the genes eae and stx2a were significantly associated with HUS-associated STEC (P < 0.05 for each parameter), while stx1 was associated with non-HUS-associated STEC (P < 0.05). All of the potential virulence genes analyzed, except ehxA, were significantly more frequent among HUS-associated than non-HUS-associated strains (P < 0.05 for each gene). However, these genes were also present in some non-HUS-associated STEC strains and could therefore not reliably differentiate between HUS-associated and non-HUS-associated STEC strains.
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: K
authors.initials: K
authors.lastname: Haugum
authors.affiliation: Department of Foodborne Infections, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: L T
authors.initials: LT
authors.lastname: Brandal
authors.affiliation: Gene Technology Section, Akershus University Hospital, Lørenskog, Norway.
authors.forename: B-A
authors.initials: BA
authors.lastname: Lindstedt
authors.affiliation: Department of Foodborne Infections, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: A L
authors.initials: AL
authors.lastname: Wester
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway Department of Medical Microbiology, St. Olavs University Hospital, Trondheim, Norway.
authors.forename: K
authors.initials: K
authors.lastname: Bergh
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway Department of Medical Microbiology, St. Olavs University Hospital, Trondheim, Norway jan.afset@ntnu.no.
authors.forename: J E
authors.initials: JE
authors.lastname: Afset
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics; D000293:Adolescent; D001419:Bacteria; D002648:Child; D002675:Child, Preschool; D004927:Escherichia coli Infections / Q000175:diagnosis*; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D058889:Molecular Typing; D016133:Polymerase Chain Reaction / Q000379:methods*; D012703:Serotyping; D022622:Shiga Toxin 1 / Q000235:genetics; D022641:Shiga Toxin 2 / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; D037521:Virulence Factors; C073819:eaeA protein, E coli