Recurrent seasonal outbreak of an emerging serotype of Shiga toxin-producing Escherichia coli (STEC O55:H7 Stx2a) in the south west of England, July 2014 to September 2015

Abstract

The first documented British outbreak of Shiga toxin-producing Escherichia coli (STEC) O55:H7 began in the county of Dorset, England, in July 2014. Since then, there have been a total of 31 cases of which 13 presented with haemolytic uraemic syndrome (HUS). The outbreak strain had Shiga toxin (Stx) subtype 2a associated with an elevated risk of HUS. This strain had not previously been isolated from humans or animals in England. The only epidemiological link was living in or having close links to two areas in Dorset. Extensive investigations included testing of animals and household pets. Control measures included extended screening, iterative interviewing and exclusion of cases and high risk contacts. Whole genome sequencing (WGS) confirmed that all the cases were infected with similar strains. A specific source could not be identified. The combination of epidemiological investigation and WGS indicated, however, that this outbreak was possibly caused by recurrent introductions from a local endemic zoonotic source, that a highly similar endemic reservoir appears to exist in the Republic of Ireland but has not been identified elsewhere, and that a subset of cases was associated with human-to-human transmission in a nursery.

Antimicrobial resistance in Shiga toxin-producing Escherichia coli other than serotype O157 : H7 in England, 2014–2016

“…Only one outbreak in England during the time frame of the study was caused by non-O157 STEC. This outbreak comprised 28 isolates of STEC O55 : H7 belonging to CC335 [15]; 2 representative isolates were selected for phenotypic AST.…”

Shiga toxin-producing Escherichia coli haemolytic uraemic syndrome (STEC-HUS): diagnosis, surveillance and public-health management in England

“…Failure to obtain an accurate, timely diagnosis of STEC-HUS has a detrimental effect on prompt notification to PHE; thus, delaying effective public-health action with respect to contact tracing and preventing ongoing transmission. Outbreaks of HUS caused by non-O157 STEC are particularly challenging, as evidenced by a recurrent outbreak of STEC O55:H7 in England that occurred between 2014 and 2018 [9, 13]. The source of the causative organism has still not been identified, although evidence suggests that transmission to the human cases had occurred via exposure to environmental contamination.…”

Hazard Identification and Characterization: Criteria for Categorizing Shiga Toxin–Producing Escherichia coli on a Risk Basis†

“…Serotype O157:H7 is the prototypic STEC that has caused infections worldwide. Serotype O26:H11 also seems prevalent and has caused infections in many countries, but other serotypes have caused infections only in a particular country or region (5,98,120), suggesting that there may be regional variations in STEC serotypes of importance. For example, in 2009, the EFSA (37) identified STEC with stx and eae from five O groups (O157, O26, O103, O111, and O145), also known as the ''big 5,'' as being of health concern in the European Union (EU).…”