title: Phylogenetic relationships of Shiga toxin-producing Escherichia coli isolated from Peruvian children.
abstract: The aim of this study was to determine the prevalence, virulence factors (stx, eae, ehxA and astA) and phylogenetic relationships [PFGE and multilocus sequence typing (MLST)] of Shiga toxin-producing Escherichia coli (STEC) strains isolated from four previous cohort studies in 2212 Peruvian children aged <36 months. STEC prevalence was 0.4 % (14/3219) in diarrhoeal and 0.6 % (15/2695) in control samples. None of the infected children developed haemolytic uraemic syndrome (HUS) or other complications of STEC. stx1 was present in 83 % of strains, stx2 in 17 %, eae in 72 %, ehxA in 59 % and astA in 14 %. The most common serotype was O26 : H11 (14 %) and the most common seropathotype was B (45 %). The strains belonged mainly to phylogenetic group B1 (52 %). The distinct combinations of alleles across the seven MLST loci were used to define 13 sequence types among 19 STEC strains. PFGE typing of 20 STEC strains resulted in 19 pulsed-field patterns. Comparison of the patterns revealed 11 clusters (I-XI), each usually including strains belonging to different serotypes; one exception was cluster VI, which gathered exclusively seven strains of seropathotype B, clonal group enterohaemorrhagic E. coli (EHEC) 2 and phylogenetic group B1. In summary, STEC prevalence was low in Peruvian children with diarrhoea in the community setting. The strains were phylogenetically diverse and associated with mild infections. However, additional studies are needed in children with bloody diarrhoea and HUS.
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: C A
authors.initials: CA
authors.lastname: Contreras
authors.affiliation: University of Texas School of Public Health, Houston, USA.|Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: T J
authors.initials: TJ
authors.lastname: Ochoa
authors.affiliation: CIBERESP, Barcelona, Spain.|Centre de Recerca en Salut Internacional de Barcelona, Hospital Clinic/Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Ruiz
authors.affiliation: US Food and Drug Administration, Laurel, Maryland, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Lacher
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: F P
authors.initials: FP
authors.lastname: Rivera
authors.affiliation: Área de Microbiología Molecular, Centro de Investigación Biomédica La Rioja, Logroño, Spain.
authors.forename: Y
authors.initials: Y
authors.lastname: Saenz
authors.affiliation: Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: E
authors.initials: E
authors.lastname: Chea-Woo
authors.affiliation: Instituto de Investigación Nutricional, Lima, Peru.
authors.forename: N
authors.initials: N
authors.lastname: Zavaleta
authors.affiliation: Instituto de Investigación Nutricional, Lima, Peru.
authors.forename: A I
authors.initials: AI
authors.lastname: Gil
authors.affiliation: Escuela de Medicina, Universidad Peruana de Ciencias Aplicadas, Lima, Peru.|Instituto de Investigación Nutricional, Lima, Peru.
authors.forename: C F
authors.initials: CF
authors.lastname: Lanata
authors.affiliation: Instituto Nacional de Salud del Niño, Lima, Peru.|Universidad Nacional Mayor de San Marcos, Lima, Peru.|Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: L
authors.initials: L
authors.lastname: Huicho
authors.affiliation: US Naval Medical Research Center Detachment, Department of Bacteriology, Lima, Peru.
authors.forename: R C
authors.initials: RC
authors.lastname: Maves
authors.affiliation: Área de Microbiología Molecular, Centro de Investigación Biomédica La Rioja, Logroño, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Torres
authors.affiliation: E. coli Reference Center, Department of Veterinary and Biomedical Sciences, Pennsylvania State University, Pennsylvania, USA.
authors.forename: C
authors.initials: C
authors.lastname: DebRoy
authors.affiliation: University of Texas School of Public Health, Houston, USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Cleary
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics; D001483:Base Sequence; D016022:Case-Control Studies; D002675:Child, Preschool; D015331:Cohort Studies; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D005798:Genes, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D058885:Multilocus Sequence Typing; D010568:Peru / Q000453:epidemiology; D010802:Phylogeny; D015995:Prevalence; D012703:Serotyping; D022621:Shiga Toxin / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics
chemical_list: D018829:Adhesins, Bacterial; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D037521:Virulence Factors; C073819:eaeA protein, E coli; D022621:Shiga Toxin