Multiple-locus variable-number tandem-repeat analysis (MLVA) of 0157:H7 and non-0157 verocytotoxigenic Escherichia coli from Argentina

BUSTAMANTE A. V., SANSO A. M., LUCCHESI P. M. A. & PARMA A. E

INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY (PRINT)

ELSEVIER Editorial Sistem

Año: 2010 vol. 300 p. 212 - 217

1438-4221

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 of Tandem Repeats 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 seven 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 two 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 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.