Outbreak of Shiga Toxin–Producing Escherichia coli (STEC) O104:H4 Infection in Germany Causes a Paradigm Shift with Regard to Human Pathogenicity of STEC Strains

Abstract

<jats:p>An outbreak that comprised 3,842 cases of human infections with enteroaggregative hemorrhagic Escherichia coli (EAHEC) O104:H4 occurred in Germany in May 2011. The high proportion of adults affected in this outbreak and the unusually high number of patients that developed hemolytic uremic syndrome makes this outbreak the most dramatic since enterohemorrhagic E. coli (EHEC) strains were first identified as agents of human disease. The characteristics of the outbreak strain, the way it spread among humans, and the clinical signs resulting from EAHEC infections have changed the way Shiga toxin–producing E. coli strains are regarded as human pathogens in general. EAHEC O104:H4 is an emerging E. coli pathotype that is endemic in Central Africa and has spread to Europe and Asia. EAHEC strains have evolved from enteroaggregative E. coli by uptake of a Shiga toxin 2a (Stx2a)–encoding bacteriophage. Except for Stx2a, no other EHEC-specific virulence markers including the locus of enterocyte effacement are present in EAHEC strains. EAHEC O104:H4 colonizes humans through aggregative adherence fimbrial pili encoded by the enteroaggregative E. coli plasmid. The aggregative adherence fimbrial colonization mechanism substitutes for the locus of enterocyte effacement functions for bacterial adherence and delivery of Stx2a into the human intestine, resulting clinically in hemolytic uremic syndrome. Humans are the only known natural reservoir known for EAHEC. In contrast, Shiga toxin–producing E. coli and EHEC are associated with animals as natural hosts. Contaminated sprouted fenugreek seeds were suspected as the primary vehicle of transmission of the EAHEC O104:H4 outbreak strain in Germany. During the outbreak, secondary transmission (human to human and human to food) was important. Epidemiological investigations revealed fenugreek seeds as the source of entry of EAHEC O104:H4 into the food chain; however, microbiological analysis of seeds for this pathogen produced negative results. The survival of EAHEC in seeds and the frequency of human carriers of EAHEC should be investigated for a better understanding of EAHEC transmission routes.</jats:p>

One Health surveillance – More than a buzz word?

“…During one of the largest multi-country, food-borne outbreaks in Europe, many 85 aspects of collaborative surveillance were discussed and recommendations made for improvements 86 (Beutin and Martin, 2012). Also, examples of successful surveillance collaboration were reported 87 during ICAHS for influenza (Bruhn et al, 2014) and for rabies (Mtema et years.…”

Defects in RNA polyadenylation impair both lysogenization by and lytic development of Shiga toxin-converting bacteriophages

“…The severity of medical problems caused by STEC strains can be exemplified by the outbreak that occurred in Germany in 2011. Its fatal results, summarized as over 4000 symptomatic infections and over 50 cases of death, besides confirming the importance of the problem, also underlined our incomplete knowledge about regulatory mechanisms operating during development of the Stx phages (Mellmann et al, 2011;Beutin & Martin, 2012;Bloch et al, 2012;Karch et al, 2012;Werber et al, 2012).…”

Pathogen and Toxin Entry - How Pathogens and Toxins Induce and Harness Endocytotic Mechanisms

“…In humans, these toxins cause serious complications in the gastrointestinal tract, including haemolytic colitis, which may (especially in children and elderly people) further progress to hemolytic-uremic syndrome (HUS) and severe complications of the central nervous system [22,23]. Most recently, more than 50 patients in Germany died of EHEC infections [24][25][26].…”