Genetic diversity of O157:H7 and non-O157 verocytotoxigenic Escherichia coli from Argentina inferred from multiple-locus variable-number tandem repeat analysis (MLVA).
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 additional research in order to find more VNTR loci that could allow a higher discrimination among non-O157 VTEC.
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. avbustaman@vet.unicen.edu.ar
Ana V
AV
Bustamante
A Mariel
AM
Sanso
Paula M A
PM
Lucchesi
Alberto E
AE
Parma
D000818:Animals; D001118:Argentina / Q000453:epidemiology; D015373:Bacterial Typing Techniques; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology / Q000662:veterinary*; D005516:Food Microbiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D018598:Minisatellite Repeats; D017720:Molecular Epidemiology; D012680:Sensitivity and Specificity; D012703:Serotyping; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*
D004269:DNA, Bacterial