The Importance of Shiga Toxin-Producing Escherichia coli O145:NM[H28]/H28 Infections in Argentina, 1998-2020.

Claudia Carolina Carbonari,Ariela Baschkier,Isabel Chinen,Beatriz Alejandra D’Astek,Nahuel Fittipaldi,Eduardo Manfredi,Gisela Zolezzi,Marta Rivas,Roberto Gustavo Melano,Carla Schesi,Elizabeth Sandra Miliwebsky,Natalia Lorena Deza

doi:10.3390/microorganisms10030582

Abstract

Shiga toxin-producing Escherichia coli (STEC) is known as a pathogen associated with food-borne diseases. The STEC O145 serogroup has been related with acute watery diarrhea, bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Argentina has the highest rate of HUS worldwide with 70% of the cases associated with STEC infections. We aimed to describe the epidemiology and genetic diversity of STEC O145 strains isolated across Argentina between 1998–2020. The strains isolated from 543 cases of human disease and four cattle, were pheno-genotipically characterized. Sequencing of five strains was performed. The strains were serotyped as O145:NM[H28]/H28, O145:H25, and O145:HNT, and mainly characterized as O145:NM[H28]/stx2a/eae/ehxA (98.1%). The results obtained by sequencing were consistent with those obtained by traditional methods and additional genes involved in different mechanisms of the pathogen were observed. In this study, we confirmed that STEC O145 strains are the second serogroup after O157 and represent 20.3% of HUS cases in Argentina. The frequency of STEC O145 and other significant serogroups is of utmost importance for public health in the country. This study encourages the improvement of the surveillance system to prevent severe cases of human disease.

Highlights

Shiga toxin-producing Escherichia coli (STEC) was first described as a food-borne pathogen in 1982, associated to two outbreaks of hemorrhagic colitis [1]
Considering STEC O145:NM[H28] as the second most frequent serotype associated to hemolytic uremic syndrome (HUS) in Argentina over time, we aimed to describe the epidemiology and genetic diversity of this pathogen related to human infections between 1998 and 2020
577 (16.5%, 95% confidence intervals (CIs) 15.2–17.7), including 34 strains isolated during shedding monitoring, were identified as STEC O145

Summary

Introduction

Shiga toxin-producing Escherichia coli (STEC) was first described as a food-borne pathogen in 1982, associated to two outbreaks of hemorrhagic colitis [1]. STEC infections range from mild to severe diseases. The cases, sporadic or associated to outbreaks, are typically related to the consumption of contaminated food or water [2]. Oral fecal transmission (person to person and animal to person) is a frequent route of infection. Especially cattle, are recognized as a STEC reservoir [3]. Virulent STEC strains are characterized by the production of Shiga toxin (Stx). Two types of Stx are described as Stx and Stx, and classified into different subtypes. STEC shows other pathogenicity-associated genes, the intimin, encoded by the eae gene in the Locus of Enterocyte Effacement (LEE) pathogenicity island, and enterohemolysin gene (ehxA) carried in the large virulence plasmid [4]

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