Abstract
AimShiga toxin‐producing Escherichia coli (STEC) cause bloody diarrhoea, kidney failure and occasionally death. However, identifying the source of infection caused by STEC other than serogroup O157 is hampered by the availability of sensitive methods for detecting these pathogens. In this study, we developed novel tools for detecting E. coli O55 that is potentially associated with human outbreaks.Methods and ResultsOverall specificity of immuno‐magnetic separation (IMS) beads coated with anti‐O55 serum was good with exception of cross‐reactivity with E. coli O22 and O23, which was eliminated using an O55‐specific PCR. Limit of detection for E. coli O55 using O55‐IMS beads in spiked cattle faeces was on average 50 CFU per ml (range 1–90), and improved to <10 CFU per ml using the O55‐specific PCR, following IMS on samples enriched for 2 h with E. coli O55. Application of these tools to test cattle faeces collected on‐farm allowed the isolation of O55:H19, which through whole genome sequencing was compared to STEC O55:H7 human outbreak strains.ConclusionThese tools provide a sensitive method which could be used to screen samples for STEC O55, whether environmental or human clinical.Significance and Impact of the StudySeveral human outbreaks reported in England were caused by STEC O55:H7. Tools developed here could assist in identification of the environmental source for these isolates, which has not yet been established.
Highlights
In 2014-2015, an outbreak of Shiga toxin-producing Escherichia coli (STEC) occurred in the county of Dorset, England caused by STEC serotype O55:H7 carrying stx2 and eae, encoding an adhesin present in the locus of enterocyte effacement
Identifying the source of infection caused by STEC other than serogroup O157 is hampered by availability of sensitive methods for detecting these pathogens
In this study we developed novel tools for detecting E. coli O55 that is potentially associated with human outbreaks
Summary
In 2014-2015, an outbreak of STEC occurred in the county of Dorset, England caused by STEC serotype O55:H7 carrying stx and eae, encoding an adhesin present in the locus of enterocyte effacement. 31 cases of STEC O55 infection were reported mainly in children, 13 of which developed HUS (McFarland et al, 2017). The serotype O55:H7 had not previously been associated with STEC infections in England and the source of STEC O55:H7 isolates causing infections in Dorset could not be determined despite extensive investigations (Paz, 2016). In October 2018, environmental STEC O55:H7 was again identified as the causative organism in two children from Leicestershire who developed HUS, which resulted in fatality, and again the environmental source was not identified (https://www.bbc.co.uk/news/uk-englandleicestershire-45838401; Public Health England, unpublished data)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
