Genetic diversity of O157:H7 and non-O157 verocytotoxigenic Escherichia coli from Argentina inferred from multiple-locus variable-number tandem repeat analysis (MLVA) |
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Authors: | Ana V. Bustamante A. Mariel Sanso Paula M.A. Lucchesi Alberto E. Parma |
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Affiliation: | 1. Lab. Inmunoquímica y Biotecnología, Dto. de Sanidad Animal y Medicina Preventiva, Facultad de Cs. Veterinarias, Universidad Nacional del Centro de la Pcia. de Buenos Aires, 7000 Tandil, Buenos Aires, Argentina;2. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina;3. Comisión de Investigaciones Científicas-Gobierno Pcia. Buenos Aires (CIC-PBA), Argentina |
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Abstract: | Although serotype O157:H7 has been implicated in most cases of haemolytic-uraemic syndrome (HUS), there is growing concern about non-O157 serotypes of verocytotoxigenic Escherichia coli (VTEC). Multiple-locus variable-number tandem repeat analysis (MLVA) has been focused on the specific typing of O157:H7 isolates, but recently, a generic MLVA assay for E. coli and Shigella has been developed. We performed a study of the polymorphism in 7 generic VNTR loci both in VTEC O157:H7 and non-O157 isolates from Argentina, in order to asses the ability of the method to type this group of isolates and to get insight into their genetic diversity. Sixty-four isolates from cattle, patients with diarrhoea, and contaminated food belonging to 8 different serotypes were studied. All of them could be typed by this method and revealed 41 different MLVA genotypes. The MLVA dendrogram showed 2 main clusters which corresponded to O157:H7 and non-O157, respectively. Our results confirm the suitability of this MLVA method for analyzing VTEC isolates belonging to several serotypes, both O157:H7 as well as non-O157, highlight the genetic variability of the O157:H7 serotype and the need of additonal research in order to find more VNTR loci that could allow a higher discrimination among non-O157 VTEC. |
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Keywords: | Escherichia coli MLVA O157:H7 non O157:H7 |
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