Severe Outbreak of Sorbitol‐Fermenting Escherichia coli O157 via Unpasteurized Milk and Farm Visits, Finland 2012

Abstract

Shiga toxin-producing, sorbitol-fermenting Escherichia coli O157 (SF O157) has emerged as a cause of severe human illness. Despite frequent human findings, its transmission routes and reservoirs remain largely unknown. Foodborne transmission and reservoir in cattle have been suspected, but with limited supporting evidence. This study describes the outbreak of SF O157 that occurred in Finland in 2012. The outbreak originated from a recreational farm selling unpasteurized milk, as revealed by epidemiologic and microbiological investigations, and involved six hospitalized children and two asymptomatic adults with culture-confirmed infection. An identical strain of SF O157 was isolated from patients, cattle and the farm environment, and epidemiologic analysis suggested unpasteurized milk as the vehicle of transmission. This study reports the first milkborne outbreak of SF O157, provides supporting evidence of cattle as a reservoir and highlights the health risks related to the consumption of unpasteurized milk.

Sorbitol-Fermenting Enterohemorrhagic Escherichia coli O157:H − Isolates from Czech Patients with Novel Plasmid Composition Not Previously Seen in German Isolates

“…Except for the Czech Republic, where the novel SF EHEC O157 strains account for 20% of all SF EHEC O157:H Ϫ strains isolated from patients with HUS (10), the distribution and frequencies of these strains in other geographic regions, as well as the epidemiology of these infections, are currently unknown. In the Czech Republic, a SF EHEC O157:H Ϫ strain with these unique plasmid characteristics was isolated from a cow epidemiologically associated with an HUS case (3), suggesting that cattle can be a reservoir for these novel strains, as also demonstrated for the "classical" SF EHEC O157:H Ϫ strains belonging to the German clone (6,17,18). Notably, SF E. coli O157:H Ϫ (fliC H7 ) strains that share chromosomal (presence of cdtV-ABC and eae-␥) and plasmid (presence of sfpA and absence of EHEC-hlyA and etpD) characteristics with the novel SF EHEC O157:H Ϫ strains but lack stx 2a were isolated from patients with HUS (n ϭ 1) or diarrhea (n ϭ 2) in the Czech Republic (M. Marejková and M. Bielaszewska, unpublished data).…”

Ongoing haemolytic uraemic syndrome (HUS) outbreak caused by sorbitol-fermenting (SF) Shiga toxin-producing Escherichia coli (STEC) O157, Germany, December 2016 to May 2017

“…SF STEC O157:H - was first described in Germany in 1988 [2] and subsequently caused several outbreaks in Germany [3-5] and elsewhere in Europe [6,7]. SF STEC O157 is characterised by a high pathogenicity [8,9].…”

“…SF STEC O157 was isolated from minced beef products in an outbreak involving 18 HUS cases in France in 2011 [6]. In an outbreak associated with a recreational farm visit in Finland in 2012, unpasteurised milk was the most likely vehicle and isolates from patients’ stool samples, cattle and the farm environment were identical [7]. …”

Outbreak of multiple strains of non-O157 Shiga toxin-producing and enteropathogenic Escherichia coli associated with rocket salad, Finland, autumn 2016

“…PCR-positive STEC samples were cultured and the isolates from positive cultures were sent to THL for typing. The detection of the virulence genes stx 1, stx 2, eae , hly A, and saa by PCR was performed as described previously [18]. For determination of O-serogroup, the group antiserum test and the latex agglutination tests for the most common serogroups were used as first-line method before proceeding to conventional serotyping [18].…”