Prevalence, O-genotype and Shiga toxin (Stx) 2 subtype of Stx-producing <i>Escherichia coli</i> strains isolated from Argentinean beef cattle

Abstract

The aims of this study were to investigate prevalence, O-genotype, and virulence gene profile including Shiga toxin (Stx) 2 gene-subtype of Stx-producing Escherichia coli (STEC) in beef cattle from the Bahía Blanca in Argentina. Rectal swabs were collected from 283 beef cattle in 2012. stx genes were detected in 90 (32%) out of the 283 rectal swabs by stx gene-specific PCR assay. The positive cases were 13 with stx1 , 58 with stx2, and 19 with both stx1 and stx2 . Among 90 stx gene-positive samples, 45 STEC strains were isolated, which included 3 stx1 , 34 stx2 , and eight stx1 and stx2 genes positive isolates. O-genotyping grouped 45 STEC strains into 19 different O-genotypes such as Og8, Og145, Og171, Og185 (4 from each), Og22, Og153, Og157 (3 from each) and others. Various stx2 gene-subtypes were identified in 42 STEC strains: 13 positive cases for stx2a , 11 for stx2c , 3 for stx2g , 10 for stx2a and stx2d , 4 for stx2a and stx2c , and 1 for stx2b , stx2c and stx2g . efaI gene, generally prevalent in clinical strains, was detected in relatively high in the STEC strains. These data suggest that stx2a and stx2c were distributed not only in O145 and O157 but also in minor O-genotypes of STEC in Argentina.

Identification of Five Serotypes of Enteropathogenic Escherichia coli from Diarrheic Calves and Healthy Cattle in Belgium and Comparative Genomics with Shigatoxigenic E. coli

“…With regard to the stx genes, the stx1a gene is present in eight of the ten genomesequenced bovine and human AE-STEC of different serotypes: the stx2c gene in one O177:H25 AE-STEC from a diarrheic calf and the stx2g in one bovine O156:H25 AE-STEC from the healthy cattle (ST1). The stx2c and stx1a genes are frequently detected in AE-STEC from cattle and humans, while the stx2g gene described in 2003 [29] is much rarer and is more frequently associated with cattle (healthy adults and diarrheic calves) and the environment than with humans [30][31][32].…”