Shiga toxin-producing Escherichia coli clonal complex 32, including serotype O145:H28, in the UK and Ireland

Abstract

Introduction. Shiga toxin-producing Escherichia coli (STEC) O157:H7 has been the most clinically significant STEC serotype in the UK for over four decades. Over the last 10 years we have observed a decrease in STEC O157:H7 and an increase in non-O157 STEC serotypes, such as O145:H28. Gap Statement. Little is known about the microbiology and epidemiology of STEC belonging to CC32 (including O145:H28) in the UK. The aim of this study was to integrate genomic data with patient information to gain a better understanding of the virulence, disease severity, epidemic risk assessment and population structure of this clinically significant clonal complex. Methodology. Isolates of E. coli belonging to CC32 (n=309) in the archives of public health agencies in the UK and Ireland were whole-genome-sequenced, virulence-profiled and integrated with enhanced surveillance questionnaire (ESQ) data, including exposures and disease severity. Results. Overall, diagnoses of STEC belonging to CC32 (290/309, 94 %) in the UK have increased every year since 2014. Most cases were female (61 %), and the highest proportion of cases belonged to the 0–4 age group (53/211,25 %). The frequency of symptoms of diarrhoea (92 %), abdominal pain (84 %), blood in stool (71 %) and nausea (51 %) was similar to that reported in cases of STEC O157:H7, although cases of STEC CC32 were more frequently admitted to hospital (STEC CC32 48 % vs O157:H7 34 %) and/or developed haemolytic uraemic syndrome (HUS) (STEC CC32 9 % vs O157:H7 4 %). The majority of STEC isolates (268/290, 92 %) had the stx2a/eae virulence gene combination, most commonly associated with progression to STEC HUS. There was evidence of person-to-person transmission and small, temporally related, geographically dispersed outbreaks, characteristic of foodborne outbreaks linked to nationally distributed products. Conclusion. We recommend more widespread use of polymerase chain reaction (PCR) for the detection of all STEC serogroups, the development of consistent strategies for the follow-up testing of PCR-positive faecal specimens, the implementation of more comprehensive and standardized collection of epidemiological data, and routine sharing of sequencing data between public health agencies worldwide.

Clinical and public health implications of increasing notifications of LEE-negative Shiga toxin-producing Escherichia coli in England, 2014–2022

“…2). As observed with other non-O157 STEC CCs in England [17][18][19], London (CC25 n=103/315, 33 %, CC33 n=189/528, 36 %, CC442 n=184/574, 32 %) and the South East of England (CC442 n=200/574, 35 %; CC33 n=180/528, 34 %, CC25 n=118/315, 37 %) were the two regions reporting the highest numbers of cases of LEE-negative STEC (Fig. 3).…”

“…In common with other non-O157 STEC clonal complexes in England [17][18][19], notifications of STEC belonging to CC25, CC33 and CC442 have increased every year since 2014, most likely due to the increasing number of frontline diagnostic laboratories implementing commercial PCR assays that target stx [2]. However, it is possible that this change in the diagnostic algorithm is masking a true increase in non-O157 STEC in England.…”

Escherichia coli encoding Shiga toxin subtype Stx2f causing human infections in England, 2015–2022

“…As observed with other STEC serotypes, specifically STEC O157:H7, STEC O26:H11 and STEC O145:H28 [44][45][46], most cases of E. coli encoding stx2f were female, a high proportion of cases were children under the age of 5 years old, and notifications peaked in later summer, early autumn. Prager et al [24] [24] reported a higher proportion of cases in children in Germany, and Friesema et al…”

“…However, we cannot rule out a true increase in the burden of infectious disease caused by E. coli encoding stx2f. Unlike other non-O157 STEC serotypes that we have reviewed recently where most cases were identified in the South of England, the same region where the highest density of laboratories using PCR were located [42][43][44][45], most cases of E. coli encoding stx2f were located in the North of England. As STEC surveillance is not consist across the country, it is difficult to interpret the meaningfulness of this geographical clustering, but it may be indicative of a local animal or environmental source.…”

“…coli encoding stx2f . Unlike other non-O157 STEC serotypes that we have reviewed recently where most cases were identified in the South of England, the same region where the highest density of laboratories using PCR were located [42–45], most cases of E. coli encoding stx2f were located in the North of England.…”