Shiga Toxin
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Zhongkai Lu ◽  
Zhicheng Liu ◽  
Xia Li ◽  
Xinfang Qin ◽  
Haofei Hong ◽  

Xiaomei Zhang ◽  
Michael Payne ◽  
Sandeep Kaur ◽  
Ruiting Lan

Shiga toxin-producing Escherichia coli (STEC) have more than 470 serotypes. The well-known STEC O157:H7 serotype is a leading cause of STEC infections in humans. However, the incidence of non-O157:H7 STEC serotypes associated with foodborne outbreaks and human infections has increased in recent years. Current detection and serotyping assays are focusing on O157 and top six (“Big six”) non-O157 STEC serogroups. In this study, we performed phylogenetic analysis of nearly 41,000 publicly available STEC genomes representing 460 different STEC serotypes and identified 19 major and 229 minor STEC clusters. STEC cluster-specific gene markers were then identified through comparative genomic analysis. We further identified serotype-specific gene markers for the top 10 most frequent non-O157:H7 STEC serotypes. The cluster or serotype specific gene markers had 99.54% accuracy and more than 97.25% specificity when tested using 38,534 STEC and 14,216 non-STEC E. coli genomes, respectively. In addition, we developed a freely available in silico serotyping pipeline named STECFinder that combined these robust gene markers with established E. coli serotype specific O and H antigen genes and stx genes for accurate identification, cluster determination and serotyping of STEC. STECFinder can assign 99.85% and 99.83% of 38,534 STEC isolates to STEC clusters using assembled genomes and Illumina reads respectively and can simultaneously predict stx subtypes and STEC serotypes. Using shotgun metagenomic sequencing reads of STEC spiked food samples from a published study, we demonstrated that STECFinder can detect the spiked STEC serotypes, accurately. The cluster/serotype-specific gene markers could also be adapted for culture independent typing, facilitating rapid STEC typing. STECFinder is available as an installable package ( and will be useful for in silico STEC cluster identification and serotyping using genome data.

Wiebke Pirschel ◽  
Antonio N. Mestekemper ◽  
Bianka Wissuwa ◽  
Nadine Krieg ◽  
Sarah Kröller ◽  

2021 ◽  
Vol 14 (2) ◽  
pp. 78-90
Ahmed Jarad ◽  
Kh. Al- Jeboori

The present study focus on non-O157 Shiga toxin-producing E. Coli (STEC), included a bacteriological study was subjected to provide additional information for non-O157 STEC prevalence in children and calves. Isolation by using selective culturing media (CHROMagar STEC and CHROMagar O157) from 127 children suffering from diarrhea and 133 calves in Al- Muthanna province. Characterization depends on culturing positive colony on MacConkey agar and Levin’s Eosin Methylene blue agar, staining single colony from the growth by gram stain, biochemical tests; Indole, the Methyl Red, Voges-Proskauer, Citrate test, Oxidase, Catalase, Urease, Motility, Kligler Iron and Api-20E, were done to confirm a diagnosis of non-O157 STEC, The reliable isolation as non-O157 STEC serotyping by specific latex agglutination test for the target non-O157 STEC (big six) serogroup (O26, O45, O103, O111, O121 and O145). The current study showed the prevalence of non-O157 STEC was 20 of out 127 (15.73%) in samples collected from children and 27 / 133 (20.30%) in calves samples in conclusion the Non-O157 STEC is an important cause of diarrhea in children, and calves; finally, the calves play an important reservoir for Non-O157 STEC.

2021 ◽  
Libby Obumneke Onyeka ◽  
Abiodun A. Adesiyun ◽  
Karen H. Keddy ◽  
Ayanda Manqele ◽  
Evelyn Madoroba ◽  

2021 ◽  
Vol 2021 ◽  
pp. 1-5
Omid Zarei ◽  
Leili Shokoohizadeh ◽  
Hadi Hossainpour ◽  
Mohammad Yousef Alikhani

Background. Shiga toxin-producing Escherichia coli (STEC) is known as a crucial zoonotic food-borne pathogen. A total of 257 raw chicken meat samples were collected from different markets in Hamadan, west of Iran, from January 2016 to May 2017. Materials and Methods. The samples were cultured in selective and differential culture media, and the virulence genes of E. coli isolates were analyzed by PCR assay. The antibiotic resistance patterns of E. coli isolates were determined by the disk diffusion method. The genetic relatedness of the E. coli O157 isolates was analyzed by ERIC-PCR. Results. In total, 93 (36% ± 3.12) of the isolates were identified as E. coli in this study. Based on serological and microbiological tests, 36 (38.7% ± 9.9), 7 (7.5% ± 5.35), and 12 (12.9% ± 6.81) of the E. coli isolates were characterized as STEC, enteropathogenic E. coli (EPEC), and attaching and effacing E. coli (AEEC) strains, respectively. A high level of resistance to nalidixic acid (91.4% ± 5.7), tetracycline (89.2% ± 6.31), ampicillin (82.8% ± 7.67), and trimotoprime-sulfametoxazole (71% ± 9.22) was detected among the E. coli isolates. The analysis of the ERIC-PCR results showed five different ERIC types among the E. coli O157 isolates. Conclusions. Based on our findings, control and check-up of poultry meats should be considered as a crucial issue for public health.

Microbiology ◽  
2021 ◽  
Vol 167 (12) ◽  
Takeshi Shimizu ◽  
Manami Onuki ◽  
Shin Suzuki ◽  
Shinichiro Hirai ◽  
Eiji Yokoyama ◽  

Enterohaemorrhagic Escherichia coli (EHEC) produces Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2). Although stx1 and stx2 were found within the late operons of the Stx-encoding phages (Stx-phages), stx1 could mainly be transcribed from the stx1 promoter (P Stx1), which represents the functional operator-binding site (Fur box) for the transcriptional regulator Fur (ferric uptake regulator), upstream of stx1. In this study, we found that the production of Stx1 by EHEC was affected by oxygen concentration. Increased Stx1 production in the presence of oxygen is dependent on Fur, which is an Fe2+-responsive transcription factor. The intracellular Fe2+ pool was lower under microaerobic conditions than under anaerobic conditions, suggesting that lower Fe2+ availability drove the formation of less Fe2+-Fur, less DNA binding to the P Stx1 region, and an increase in Stx1 production.

2021 ◽  
Vol 12 ◽  
Eby M. Sim ◽  
Ryan Kim ◽  
Mailie Gall ◽  
Alicia Arnott ◽  
Peter Howard ◽  

The disease caused by Shiga toxin-producing Escherichia coli (STEC) remains a significant public health challenge globally, but the incidence of human STEC infections in Australia remains relatively low. This study examined the virulence characteristics and diversity of STEC isolates in the state of New South Wales between December 2017 and May 2020. Utilisation of both whole and core genome multi-locus sequence typing (MLST) allowed for the inference of genomic diversity and detection of isolates that were likely to be epidemiologically linked. The most common STEC serotype and stx subtype detected in this study were O157:H7 and stx1a, respectively. A genomic scan of other virulence factors present in STEC suggested interplay between iron uptake system and virulence factors that mediate either iron release or countermeasures against host defence that could result in a reduction of stx1a expression. This reduced expression of the dominant stx genotype could contribute to the reduced incidence of STEC-related illness in Australia. Genomic surveillance of STEC becomes an important part of public health response and ongoing interrogation of virulence factors in STEC offers additional insights for the public health risk assessment.

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