Experimental Infection of Calves with Escherichia coli O104:H4 outbreak strain.

K Hamm,K Tauscher,S A Barth,E Lange,E Liebler-Tenorio,M Bielaszewska,C Menge,L Geue,J P Teifke,G Kotterba,H Karch,S Stalb

doi:10.1038/srep32812

Abstract

In 2011, a severe outbreak of hemolytic-uremic syndrome was caused by an unusual, highly virulent enterohemorrhagic E. coli (EHEC) O104:H4 strain, which possessed EHEC virulence traits in the genetic background of human-adapted enteroaggregative E. coli. To determine magnitude of fecal shedding and site of colonization of EHEC O104:H4 in a livestock host, 30 (ten/strain) weaned calves were inoculated with 1010 CFU of EHEC O104:H4, EHEC O157:H7 (positive control) or E. coli strain 123 (negative control) and necropsied (4 or 28 d.p.i.). E. coli O157:H7 was recovered until 28 d.p.i. and O104:H4 until 24 d.p.i. At 4 d.p.i., EHEC O104:H4 was isolated from intestinal content and detected associated with the intestinal mucosa. These results are the first evidence that cattle, the most important EHEC reservoir, can also carry unusual EHEC strains at least transiently, questioning our current understanding of the molecular basis of host adaptation of this important E. coli pathovar.

Highlights

In 2011, a severe outbreak of hemolytic-uremic syndrome was caused by an unusual, highly virulent enterohemorrhagic E. coli (EHEC) O104:H4 strain, which possessed EHEC virulence traits in the genetic background of human-adapted enteroaggregative E. coli
No significant differences were seen between the numbers of EHEC O104:H4 CFU/g shed in the feces and the respective numbers for E. coli strain or EHEC O157:H7
E. coli strains belonging to the enteroaggregative E. coli (EAEC) pathovar have not been detected in cattle, the primary STEC/EHEC reservoir far

Summary

Introduction

In 2011, a severe outbreak of hemolytic-uremic syndrome was caused by an unusual, highly virulent enterohemorrhagic E. coli (EHEC) O104:H4 strain, which possessed EHEC virulence traits in the genetic background of human-adapted enteroaggregative E. coli. O104:H4 until 24 d.p.i. At 4 d.p.i., EHEC O104:H4 was isolated from intestinal content and detected associated with the intestinal mucosa. At 4 d.p.i., EHEC O104:H4 was isolated from intestinal content and detected associated with the intestinal mucosa These results are the first evidence that cattle, the most important EHEC reservoir, can carry unusual EHEC strains at least transiently, questioning our current understanding of the molecular basis of host adaptation of this important E. coli pathovar. The strain possesses a combination of virulence factors from both Shiga toxin (Stx)-producing E. coli (STEC) and enteroaggregative E. coli (EAEC) strains[3,4] and represents a novel hybrid pathotype of enterohemorrhagic E. coli (EHEC). Clinical symptoms of EHEC infections range from mild diarrhea to HC8 and may be complicated by the potentially fatal HUS9

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Results

Conclusion