Resumo

ZOTTA, Claudio Marcelo et al. New genetic pattern of Escherichia coli O157:H7 biotype "B" in Argentina. Acta bioquím. clín. latinoam. [online]. 2009, vol.43, n.4, pp.589-592. ISSN 0325-2957.

Argentina has the highest rate oteases of hemolytic uremic syndrome (HUS) in the world. Outbreaks and sporadic cases of HUS have been associated with 0157:H7 Shiga toxin-producer Escherichia coli (STEC). The aim ofthisstudy was to compare the genetic diversity and clonal relatedness of Escherichia coli 0157-.H7 biotype B. Four biotype B strains were isolated from two patients with HUS and two asymptomatic household contaets in the city of Mar del Plata. PCR was performed to detect stx₁, stx₂, rfb_O157, eae, ehxA and fliC_h7 genes, and pulsed-field gel electrophoresis (Xbal-PFGE) to establish the genetic diversity and the clonai relatedness. All strains harbored the stx₂ stx_2c(vh-_a), eae, ehxA and fliC_h7 genes and belongea to phage type 2. By means of Xbal-PFG _, , three patterns were identified, showing high clonai relatedness and related to the same event, but there was no established epidemiológica! link between cases of HUS. These patterns of Xbal-PFGE were new, because they were not included in the datábase of E.coli 0157 in Argentina. Using tools of detection and classification for diagnosis, reference laboratories will be able to detect the emergence of new clones associated with human diseases.

Palavras-chave : Escherichia coli 0157-.H7 biotype B; Genetic diversity; Clonal relatedness; Pulsed-field gel electrophoresis.

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