Distribution of Locus of Adhesion and Autoaggregation and hes Gene in STEC Strains from Countries of Latin America

Abstract

Shiga toxin-producing Escherichia coli (STEC) are zoonotic food pathogens associated with foodborne diarrheal illness, hemorrhagic colitis, and complications such as hemolytic uremic syndrome (HUS). The ability to adhere to epithelial cells is an important virulence trait, and pathogenicity islands (PAIs) play an important role on it. Some STEC carrying a PAI named locus of enterocyte effacement (LEE-positive) have been frequently associated to HUS; however, STEC that do not carry LEE (LEE-negative) have also been associated with this outcome. The burden of disease caused by LEE-negative STEC has increased recently in several countries like Argentina, Chile, and Paraguay. A new PAI -the Locus of Adhesion and Autoagregation (LAA)-has been associated to severe disease in humans. In this study, we aimed to analyze the distribution of LAA and its possible predictor, the gene hes, in LEE-negative STEC strains isolated from Chile and Paraguay from different sources. The presence of the different LAA modules and hes were detected by PCR. LAA was found in 41.6% and 41.0% of strains isolated from Chile and Paraguay, respectively. Strains were isolated from diverse origins and belonged to several serogroups including O91, O103, and O113. The hes gene was detected in 50% of the isolates from Paraguay and Chile. Therefore, the detection of LAA and hes in STEC could complement current genetic evaluation schemes, allowing to classify LEE negative STEC strains as LAA-positive or LAA-negative STEC strains.

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

“…The acquisition of LAA is probably a recent evolutionary event in STEC, which could have contributed to the emergence of highly virulent LEE‐negative strains, and has been associated with HC and HUS (Colello, Vélez et al., 2018; Montero et al., 2017). Here, we detected this PAI in 77.8% of the strains, and its associated genes les P, hes , pag C‐like and ag 43, in 77.8%, 72.2%, 66.7% and 61.1%, respectively, which was higher than previously reported in strains isolated from people, animals and food in Argentina, Chile and Paraguay (Colello, Vélez et al., 2018; Montero et al., 2019; Vélez et al., 2020). Given these results, 57.1% of the LAA‐positive strains harboured this PAI as a complete structure with its four modules, while the remaining strains only with three modules.…”

Genomic Epidemiology of Shiga Toxin-Producing Escherichia coli Isolated from the Livestock-Food-Human Interface in South America

“…These eae-positive strains included ST11 lineages, the "big six" (O26:H11, O103:H2, O111:H8, O145:H25, and O145:H28) and other serotypes (O69:H11, O98:H21, O172:H25) considered emergent [98]. However, the burden of illness caused by LEEnegative STEC strains has recently increased in several countries, such as Argentina, Chile, and Paraguay [99]. In this study, most of the analyzed strains were LEE-negative, but harbored different adhesin-encoding genes, including lpfA, ehaA, and saa.…”

Phenotypic and genotypic characterization of Shiga toxin-producing Escherichia coli strains recovered from bovine carcasses in Uruguay

“…Moreover, some recently acquired pathogenicity islands (PAI) could collaborate to its adhesion, such as LAA. Some genes are used as markers for PAI modules, for example hes is a marker for module I and iha and lesP are markers for module II ( Vélez et al, 2020 ). Parts of this PAI was identified in 76.9% of the strains.…”