Evaluating the use of multilocus variable number tandem repeat analysis of Shiga toxin-producing Escherichia coli O157 as a routine public health tool in England.

Lisa Byrne,Kathie A Grant,Neil Perry,Goutam K Adak,John Wain,Richard Elson,Philip Ashton,Timothy J Dallman,Claire Jenkins

doi:10.1371/journal.pone.0085901

Lisa Byrne, Kathie A Grant + Show 7 more

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https://doi.org/10.1371/journal.pone.0085901

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Journal: PloS one	Publication Date: Jan 17, 2014
Citations: 31	License type: CC BY 4.0

Affiliation: Public Health England, University of East Anglia

Abstract

Multilocus variable number tandem repeat analysis (MLVA) provides microbiological support for investigations of clusters of cases of infection with Shiga toxin-producing E. coli (STEC) O157. All confirmed STEC O157 isolated in England and submitted to the Gastrointestinal Bacteria Reference Unit (GBRU) during a six month period were typed using MLVA, with the aim of assessing the impact of this approach on epidemiological investigations. Of 539 cases investigated, 341 (76%) had unique (>2 single locus variants) MLVA profiles, 12% of profiles occurred more than once due to known household transmission and 12% of profiles occurred as part of 41 clusters, 21 of which were previously identified through routine public health investigation of cases. The remaining 20 clusters were not previously detected and STEC enhanced surveillance data for associated cases were retrospectively reviewed for epidemiological links including shared exposures, geography and/or time. Additional evidence of a link between cases was found in twelve clusters. Compared to phage typing, the number of sporadic cases was reduced from 69% to 41% and the diversity index for MLVA was 0.996 versus 0.782 for phage typing. Using MLVA generates more data on the spatial and temporal dispersion of cases, better defining the epidemiology of STEC infection than phage typing. The increased detection of clusters through MLVA typing highlights the challenges to health protection practices, providing a forerunner to the advent of whole genome sequencing as a diagnostic tool.

Highlights

Shiga toxin-producing Escherichia coli (STEC) are associated with human illness and are defined by the presence of the phageencoded Shiga toxin genes, stx1 and/or stx2
STEC O157 isolates from 539 cases (96.9%) were further typed by Multilocus variable number tandem repeat analysis (MLVA) and a total of 341 unique
A number of studies have described the ease of use and timeliness of MLVA and demonstrated the discriminatory power of this approach over phage typing and pulse-field gel electrophoresis.[17,18,19]

Summary

Introduction

Shiga toxin-producing Escherichia coli (STEC) are associated with human illness and are defined by the presence of the phageencoded Shiga toxin genes, stx and/or stx. Symptoms of STEC infection range from mild gastroenteritis through to severe bloody diarrhoea and approximately 6% of cases develop haemolytic uraemic syndrome (HUS);[1] HUS is a serious condition where shiga toxins affect the blood and kidneys. It most frequently affects children and is recognised as the most common cause of kidney failure in children. The remaining 2,982 cases not attributed to outbreaks were either sporadic cases or due to person-to-person transmission within households

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