Molecular epidemiology of Shiga toxin‐producing O113:H21 isolates from cattle and meat

Abstract

The serotype O113:H21 is considered one of the relevant non-O157 STEC serotypes associated with severe human infections. Due to the increased detection of O113 strains and their relationship with clinical cases, which emphasizes the importance of this serogroup as an emerging pathogen, our aim was to determine the characteristics of STEC O113:H21 strains circulating in bovine cattle and retail meat from Argentina. For this purpose, we determined the presence and combinations of various virulence genes (and their variants) related to adhesion and toxicity in a collection of 34 isolates. Their genetic relatedness using multiple-locus variable-number tandem repeat analysis (MLVA) was also studied. Subtyping of stx genes indicated that O113:H21 strains circulating in Argentina mainly present stx alone or together with stx or, less frequent, with stx , all of which are subtypes associated with human disease. We found plasmid markers, such as saa, ehxA and subA, in a higher proportion than previous studies, and five variants of saa, two of which were novel ones. In relation to MLVA subtyping, we detected a limited diversity among the isolates considering that several loci were not discriminative and, that in some farms, the same clone seemed to remain circulating throughout the year. The O113:H21 strains studied harbour several toxin and adhesion genes (saa, espP, fimCD, ehaA, iha, hcpA, elfA, lpfO113, ecpA, subA, cdt-V) and Stx subtypes associated with human disease. Results also highlighted that subtyping of stx and saa is useful to discriminate O113:H21 strains that share virulence genes. In conclusion, this study shows that a number of O113:H21 strains that occur in foods and bovines could be pathogenic for humans. This situation calls for further attention in the prevention and control of foodborne disease caused by these strains.

Genomic features and antimicrobial resistance patterns of Shiga toxin‐producing Escherichia coli strains isolated from food in Chile

“…This serotype, together with serotypes O130:H1 and O174:H21, have been the most frequently detected among STEC strains in food, dairy cows, beef abattoirs, beef carcasses and cuts and trimmings in slaughterhouses in South American countries (Torres et al., 2018). Furthermore, all the identified serotypes have been associated with human infections (Alonso et al., 2016; Cadona et al., 2016; González‐Escalona & Kase, 2019; Miko et al., 2013; Sanso et al., 2018). In Chile, the most frequently isolated serogroups from human clinical samples belong to O157 and O26 serogroups, whereas O113:H21 has been the most frequently detected in food (ISP, 2017).…”

Whole-Genome Phylogenetic Analysis Reveals a Wide Diversity of Non-O157 STEC Isolated From Ground Beef and Cattle Feces

“…Mellmann et al, 2008;Käppeli et al, 2011). Studies in Argentina showed that STEC O113:H21 has been isolated also from beef and cattle, and it has been recently isolated from humans, pointing out that this is an emerging serotype in the country (DebRoy et al, 2004;Cadona et al, 2016;Sanso et al, 2018). Studies in Brazil have also isolated this serotype from cattle (Bando et al, 2017;Dos Santos et al, 2018).…”

Diversity of Non-O157 Shiga Toxin-Producing Escherichia coli Isolated from Cattle from Central and Southern Chile

“…Serotypes O116:H21 ST58 and O168:H8 ST718 were the most represented; these have been previously isolated from cattle [ 48 , 49 , 50 ]. Furthermore, serotypes O26:H11, O91:H21, O113:H21, O116:H21, and O130:H11, characterized in this study, have also caused disease and human outbreaks [ 51 , 52 , 53 ]. For example, STEC O116:H21 was isolated in Argentina from ground beef [ 54 ] and cattle feces [ 55 ].…”

“…In Chile, official reports indicate STEC O113 is one of the most frequent serogroups isolated from meats [ 9 ]. In Argentina, STEC O113 has been isolated from ground beef and cattle, and it has also caused human disease, rising as an emerging serotype in the country [ 53 , 54 ]. We also reported one strain of the Big Six groups: STEC O26:H11.…”