Category Archives: STX 2

RASFF Alert – STEC E.coli 1 and ” – Capreolus (Roe Deer)

Posted on October 4, 2024 by KSW | Leave a comment

STEC E.coli 1 and ” found in Capreolus from United Kingdom

Posted in food contamination, food handler, Food Hazard, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, Food Quality, food recall, Food Safety, Food Safety Alert, Food Safety Management, Food Safety Regulations, RASFF, STEC, STEC E.coli, STX 1, STX 2

Research – The microbiological quality of flour products in the UK with respect to Salmonella and Shiga-toxin-producing Escherichia coli

Posted on August 1, 2024 by KSW | Leave a comment

Applied Microbiology

Abstract

Aim

To investigate the possible contamination of raw flour and raw flour-based products, such as pancake/batter mixes, with Salmonella, generic Escherichia coli, and Shiga-toxin-producing E. coli (STEC). Samples included flours available for sale in the UK over a period of four months (January to April 2020). The Bread and Flour regulations, 1998 state the permitted ingredients in flour and bread but it does not specify the regular monitoring of the microbiological quality of flour and flour-based products.

Methods and results

Samples of raw flour were collected by local authority sampling officers in accordance with current guidance on microbiological food sampling then transported to the laboratory for examination. Microbiological testing was performed to detect Salmonella spp., generic E. coli, and STEC characterized for the presence of STEC virulence genes: stx1, stx2, and subtypes, eae, ipah, aggR, lt, sth, and stp, using molecular methods Polymerase Chain Reaction (PCR). Of the 882 flours sampled, the incidence of Salmonella was 0.1% (a single positive sample that contained multiple ingredients such as flour, dried egg, and dried milk, milled in the UK), and 68 samples (7.7%) contained generic E. coli at a level of >20 CFU/g. Molecular characterization of flour samples revealed the presence of the Shiga-toxin (stx) gene in 10 samples (5 imported and 5 from the UK) (1.1%), from which STEC was isolated from 7 samples (0.8%). Salmonella and STEC isolates were sequenced to provide further characterization of genotypes and to compare to sequences of human clinical isolates held in the UKHSA archive. Using our interpretive criteria based on genetic similarity, none of the STEC flour isolates correlated with previously observed human cases, while the singular Salmonella serotype Newport isolate from the mixed ingredient product was similar to a human case in 2019, from the UK, of S. Newport. Although there have been no reported human cases of STEC matching the isolates from these flour samples, some of the same serotypes and stx subtypes detected are known to have caused illness in other contexts.

Conclusion

Results indicate that while the incidence was low, there is a potential for the presence of Salmonella and STEC in flour, and a genetic link was demonstrated between a Salmonella isolate from a flour-based product and a human case of salmonellosis.

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Posted in Food Microbiology Research, Research, Salmonella, STEC, STEC E.coli, STX 1, STX 2

Research – Shiga Toxin-Producing Escherichia coli Strains from Romania: A Whole Genome-Based Description

Posted on July 28, 2024 by KSW | Leave a comment

MDPI

Abstract

The zoonotic Shiga toxin-producing Escherichia coli (STEC) group is unanimously regarded as exceptionally hazardous for humans. This study aimed to provide a genomic perspective on the STEC recovered sporadically from humans and have a foundation of internationally comparable data. Fifty clinical STEC isolates, representing the culture-confirmed infections reported by the STEC Reference Laboratory between 2016 and 2023, were subjected to whole-genome sequencing (WGS) analysis and sequences were interpreted using both commercial and public free bioinformatics tools. The WGS analysis revealed a genetically diverse population of STEC dominated by non-O157 serogroups commonly reported in human STEC infections in the European Union. The O26:H11 strains of ST21 lineage played a major role in the clinical disease resulting in hospitalisation and cases of paediatric HUS in Romania surpassing the O157:H7 strains. The latter were all clade 7 and mostly ST1804. Notably, among the Romanian isolates was a stx2a-harbouring cryptic clade I strain associated with a HUS case, stx2f– and stx2e-positive strains, and hybrid strains displaying a mixture of intestinal and extra intestinal virulence genes were found. As a clearer picture emerges of the STEC strains responsible for infections in Romania, further surveillance efforts are needed to uncover their prevalence, sources, and reservoirs.

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Posted in E.coli O157, E.coli O157:H7, Food Microbiology Research, HUS, Research, STEC, STEC E.coli, STX 1, STX 2, WGS

Research – Genomic analysis of an outbreak of Shiga toxin-producing Escherichia coli O183:H18 in the United Kingdom, 2023

Posted on June 6, 2024 by KSW | Leave a comment

Microbiology Research

In June 2023, UKHSA surveillance systems detected an outbreak of severe gastrointestinal symptoms caused by a rare serotype of Shiga toxin-producing Escherichia coli, STEC O183:H18. There were 26 cases aged 6 months to 74 years (42 % cases were aged 0–9 years), distributed across the UK with onset dates range between 22 May 2023 and 4 July 2023. The epidemiological and food chain investigations were inconclusive, although meat products made from beef mince were implicated as a potential vehicle. The outbreak strain belonged to sequence type (ST) 657 and harboured a Shiga toxin (stx) subtype stx2a located on a prophage that was unique in the UKHSA stx-encoding bacteriophage database. Plasmid encoded, putative virulence genes subA, ehxA, saa, iha, lpfA and iss were detected, however, the established STEC virulence genes involved in attachment to the gut mucosa (eae and aggR) were absent. The acquisition of stx across the global population structure of ST657 appeared to correspond with the presence of subA, ehxA, saa, iha, lpfA and iss. During the outbreak investigation, we used long read sequencing to characterise the plasmid and prophage content of this atypical STEC, to look for evidence to explain its recent emergence. Although we were unable to determine source and transmission route of the outbreak strain, the genomic analysis revealed potential clues as to how novel strains for STEC evolve. With the implementation of PCR capable of detecting all STEC, and genome sequencing for typing and virulence profiling, we have the tools to enable us to monitor the changing landscape of STEC. Improvements in the standardised collection of epidemiological data and trace-back strategies within the food industry, will ensure we have a surveillance system capable of alerting us to emerging threats to public health.

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Posted in E.coli O183, food bourne outbreak, Food Illness, Food Poisoning Illness, Foodborne Illness, Foodborne Illness Death, foodborne outbreak, foodbourne outbreak, Illness, outbreak, STEC, STEC E.coli, STX 1, STX 2

Research – Genomic surveillance of STEC/EHEC infections in Germany 2020 to 2022 permits insight into virulence gene profiles and novel O-antigen gene clusters

Posted on March 18, 2024 by KSW | Leave a comment

Science Direct

Abstract

Shiga toxin-producing E. coli (STEC), including the subgroup of enterohemorrhagic E. coli (EHEC), are important bacterial pathogens which cause diarrhea and the severe clinical manifestation hemolytic uremic syndrome (HUS). Genomic surveillance of STEC/EHEC is a state-of-the-art tool to identify infection clusters and to extract markers of circulating clinical strains, such as their virulence and resistance profile for risk assessment and implementation of infection prevention measures. The aim of the study was characterization of the clinical STEC population in Germany for establishment of a reference data set. To that end, from 2020 to 2022 1257 STEC isolates, including 39 of known HUS association, were analyzed and lead to a classification of 30.4 % into 129 infection clusters. Major serogroups in all clinical STEC analyzed were O26, O146, O91, O157, O103, and O145; and in HUS-associated strains were O26, O145, O157, O111, and O80. stx1 was less frequently and stx2 or a combination of stx, eaeA and ehxA were more frequently found in HUS-associated strains. Predominant stx gene subtypes in all STEC strains were stx1a (24 %) and stx2a (21 %) and in HUS-associated strains were mainly stx2a (69 %) and the combination of stx1a and stx2a (12.8 %). Furthermore, two novel O-antigen gene clusters (RKI6 and RKI7) and strains of serovars O45:H2 and O80:H2 showing multidrug resistance were detected. In conclusion, the implemented surveillance tools now allow to comprehensively define the population of clinical STEC strains including those associated with the severe disease manifestation HUS reaching a new surveillance level in Germany.

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Posted in E.coli O103, E.coli O145, E.coli O157, E.coli O157:H7, E.coli O26, E.coli O26 :H11, eae, EHEC, Emerging Pathogen, Enterohaemorrhagic Escherichia coli, Food Pathogen, Haemolytic Uremic Syndrome, HUS, O103, O146, Pathogen, pathogenic, STEC, STEC E.coli, STX 1, STX 2

Research – Shiga toxin-producing Escherichia coli (STEC) in meat and leafy greens available in the Swedish retail market – Occurrence and diversity of stx subtypes and serotypes

Posted on January 23, 2024 by KSW | Leave a comment

Science Direct

Abstract

Shiga toxin-producing Escherichia coli (STEC) is a major cause of foodborne illness, ranging from mild diarrhea to permanent kidney failure. This study summarizes the results of four surveys performed at different time periods, which investigated the occurrence and characteristics of STEC in beef, lamb and leafy greens available in the Swedish retail market. Such data is required when assessing the public health risk of varying types of STEC in different foods, and for establishing risk management measures. Samples from domestic and imported products were collected based on their availability in the retail market. The occurrence of STEC was investigated in 477 samples of beef, 330 samples of lamb and 630 samples of leafy greens. The detection of virulence genes (stx₁, stx₂, eae) was performed using real-time PCR followed by the isolation of bacteria from stx-positive enriched samples using immunomagnetic separation or an immunoblotting method. All STEC isolated from the food samples was further characterised in terms of stx subtyping and serotyping through whole genome sequencing. STEC was isolated from 2 to 14 % of beef samples and 20 to 61 % of lamb samples, depending on the region of origin. STEC was not isolated from samples of leafy greens, although stx genes were detected in 11 (2 %) of the samples tested. In total, 5 of the 151 sequenced STEC isolates from meat contained stx2 and eae, of which 4 such combinations had the stx_2a subtype. The stx₂ gene, stx_2a in particular, is strongly associated with serious disease in humans, especially in combination with the eae gene. The isolates belonged to 20 different serotypes. Two isolates from beef and one from lamb belonged to the serotype O157:H7 and contained genes for stx₂ and eae. Overall, several combinations of stx subtypes were found in isolates from beef, whereas stx_1c, either alone or together with stx_2b, was the dominant combination found in STEC from lamb. In conclusion, STEC was rare in whole meat samples of domestic beef in the Swedish retail market, whereas such bacteria were frequently found in minced meat and whole meat samples of imported beef and domestic and imported lamb. Although the number of isolates containing genes linked to an increased risk of severe disease was low, beef and lamb in the Swedish retail market is a common source of human exposure to potentially pathogenic STEC.

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Posted in eae, eaeA, Food Microbiology Research, PCR, Research, Shigatoxin, STEC, STEC E.coli, STX 1, STX 2

EFSA – Story map on Shiga toxin-producing Escherichia coli

Posted on December 13, 2023 by KSW | Leave a comment

EFSA

Shiga toxin-producing Escherichia coli (STEC) are strains of the bacterium Escherichia coli that produce cytotoxins known as Shiga toxins and that can be transmitted from animals to humans. Shiga toxins are proteins that have a cytotoxic effect, meaning they can harm cells. These toxins exist in two primary forms: Stx1 and Stx2. Each form can be neutralized by different antibodies. Further, these toxin types are subdivided into multiple subtypes based on small genetic variations. For example, Stx1 includes subtypes such as stx1a, stx1c, and stx1d. Similarly, Stx2 has several subtypes, more than ten described up to now, including stx2a, stx2b, and so on. ( Scheutz et al., 2012 ; Bai et al., 2021 ).

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Posted in eae, Food Microbiology Research, Research, Shigatoxin, STEC, STEC E.coli, STX 1, STX 2

RASFF Alert- STEC E.coli – Bovine Meat

Posted on November 3, 2023 by KSW | Leave a comment

RASFF

STEC (stx+;eae+) in bovine meat from Belgium in France

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Posted in eae, eaeA, food contamination, food handler, Food Hazard, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, Food Quality, food recall, Food Safety, Food Safety Alert, Food Safety Management, Food Safety Regulations, Food Testing, RASFF, STEC, STEC E.coli, STX 1, STX 2

Research – Analysis of Escherichia coli O157 strains in cattle and humans between Scotland and England & Wales: implications for human health

Posted on October 19, 2023 by KSW | Leave a comment

Microbiology Research

ABSTRACT

For the last two decades, the human infection frequency of Escherichia coli O157 (O157) in Scotland has been 2.5-fold higher than in England and Wales. Results from national cattle surveys conducted in Scotland and England and Wales in 2014/2015 were combined with data on reported human clinical cases from the same time frame to determine if strain differences in national populations of O157 in cattle could be associated with higher human infection rates in Scotland. Shiga toxin subtype (Stx) and phage type (PT) were examined within and between host (cattle vs human) and nation (Scotland vs England and Wales). For a subset of the strains, whole genome sequencing (WGS) provided further insights into geographical and host association. All three major O157 lineages (I, II, I/II) and most sub-lineages (Ia, Ib, Ic, IIa, IIb, IIc) were represented in cattle and humans in both nations. While the relative contribution of different reservoir hosts to human infection is unknown, WGS analysis indicated that the majority of O157 diversity in human cases was captured by isolates from cattle. Despite comparable cattle O157 prevalence between nations, strain types were localized. PT21/28 (sub-lineage Ic, Stx2a+) was significantly more prevalent in Scottish cattle [odds ratio (OR) 8.7 (2.3–33.7; P<0.001] and humans [OR 2.2 (1.5–3.2); P<0.001]. In England and Wales, cattle had a significantly higher association with sub-lineage IIa strains [PT54, Stx2c; OR 5.6 (1.27–33.3); P=0.011] while humans were significantly more closely associated with sub-lineage IIb [PT8, Stx1 and Stx2c; OR 29 (4.9–1161); P<0.001]. Therefore, cattle farms in Scotland were more likely to harbour Stx2a+O157 strains compared to farms in E and W (P<0.001). There was evidence of limited cattle strain migration between nations and clinical isolates from one nation were more similar to cattle isolates from the same nation, with sub-lineage Ic (mainly PT21/28) exhibiting clear national association and evidence of local transmission in Scotland. While we propose the higher rate of O157 clinical cases in Scotland, compared to England and Wales, is a consequence of the nationally higher level of Stx2a+O157 strains in Scottish cattle, we discuss the multiple additional factors that may also contribute to the different infection rates between these nations.