scholarly journals Molecular Characterization of the Enterohemolysin Gene (ehxA) in Clinical Shiga Toxin-Producing Escherichia coli Isolates

Toxins ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 71
Author(s):  
Ying Hua ◽  
Ji Zhang ◽  
Cecilia Jernberg ◽  
Milan Chromek ◽  
Sverker Hansson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Clinical Symptoms ◽  
Foodborne Pathogen ◽  
Clinical Samples ◽  
Bloody Stool ◽  
Subtype B ◽  
Risk Predictor ◽  
Risk Predictors ◽  
Subtype A

Shiga toxin (Stx)-producing Escherichia coli (STEC) is an important foodborne pathogen with the ability to cause bloody diarrhea (BD) and hemolytic uremic syndrome (HUS). Little is known about enterohemolysin-encoded by ehxA. Here we investigated the prevalence and diversity of ehxA in 239 STEC isolates from human clinical samples. In total, 199 out of 239 isolates (83.26%) were ehxA positive, and ehxA was significantly overrepresented in isolates carrying stx2a + stx2c (p < 0.001) and eae (p < 0.001). The presence of ehxA was significantly associated with BD and serotype O157:H7. Five ehxA subtypes were identified, among which, ehxA subtypes B, C, and F were overrepresented in eae-positive isolates. All O157:H7 isolates carried ehxA subtype B, which was related to BD and HUS. Three ehxA groups were observed in the phylogenetic analysis, namely, group Ⅰ (ehxA subtype A), group Ⅱ (ehxA subtype B, C, and F), and group Ⅲ (ehxA subtype D). Most BD- and HUS-associated isolates were clustered into ehxA group Ⅱ, while ehxA group Ⅰ was associated with non-bloody stool and individuals ≥10 years of age. The presence of ehxA + eae and ehxA + eae + stx2 was significantly associated with HUS and O157:H7 isolates. In summary, this study showed a high prevalence and the considerable genetic diversity of ehxA among clinical STEC isolates. The ehxA genotypes (subtype B and phylogenetic group Ⅱ) could be used as risk predictors, as they were associated with severe clinical symptoms, such as BD and HUS. Furthermore, ehxA, together with stx and eae, can be used as a risk predictor for HUS in STEC infections.

scholarly journals High-Quality Whole-Genome Sequences for 77 Shiga Toxin-Producing Escherichia coli Strains Generated with PacBio Sequencing

2018 ◽  
Vol 6 (19) ◽  
Author(s):  
Pooja N. Patel ◽  
Rebecca L. Lindsey ◽  
Lisley Garcia-Toledo ◽  
Lori A. Rowe ◽  
Dhwani Batra ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Foodborne Pathogen ◽  
Severe Illness ◽  
Whole Genome ◽  
Genome Sequences ◽  
Pacbio Sequencing ◽  
High Quality ◽  
Content Type ◽  
Sequencing Platform

ABSTRACT Shiga toxin-producing Escherichia coli (STEC) is an enteric foodborne pathogen that can cause mild to severe illness. Here, we report the availability of high-quality whole-genome sequences for 77 STEC strains generated using the PacBio sequencing platform.

An Automated Fluorescent PCR Method for Detection of Shiga Toxin-Producing Escherichia coli in Foods

1998 ◽  
Vol 64 (11) ◽  
pp. 4210-4216 ◽  
Author(s):  
Shu Chen ◽  
Renlin Xu ◽  
Arlene Yee ◽  
Kai Yuan Wu ◽  
Chang-Ning Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Raw Milk ◽  
Clinical Samples ◽  
Pcr Assay ◽  
System A ◽  
Pure Cultures ◽  
Pcr Method ◽  
Meat Samples ◽  
Shiga Toxin Genes

ABSTRACT An automated fluorescence-based PCR system (a model AG-9600 AmpliSensor analyzer) was investigated to determine whether it could detect Shiga toxin-producing Escherichia coli (STEC). The AmpliSensor PCR assay involves amplification-mediated disruption of a fluorogenic DNA signal duplex (AmpliSensor) that is homologous to conserved target sequences in a 323-bp amplified fragment of Shiga toxin genes stx 1, stx 2, and stx e. Using the Amplisensor assay, we detected 113 strains of STEC belonging to 50 different serotypes, while 18 strains of non-Shiga-toxin-producing E. coli and 68 strains of other bacteria were not detected. The detection limits of the assay were less than 1 to 5 CFU per PCR mixture when pure cultures of five reference strains were used and 3 CFU per 25 g of food when spiked ground beef samples that were preenriched overnight were used. The performance of the assay was also evaluated by using 53 naturally contaminated meat samples and 48 raw milk samples. Thirty-two STEC-positive samples that were confirmed to be positive by the culture assay were found to be positive when the AmpliSensor assay was used. Nine samples that were found to be positive when the PCR assay was used were culture negative. The system described here is an automated PCR-based system that can be used for detection of all serotypes of STEC in food or clinical samples.

scholarly journals Real-Time PCR Assay for Detection and Differentiation of Shiga Toxin-Producing Escherichia coli from Clinical Samples

2015 ◽  
Vol 53 (7) ◽  
pp. 2148-2153 ◽  
Author(s):  
Xuan Qin ◽  
Eileen J. Klein ◽  
Emmanouil Galanakis ◽  
Anita A. Thomas ◽  
Jennifer R. Stapp ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Shiga Toxin ◽  
Real Time Pcr ◽  
Primary Cultures ◽  
Clinical Samples ◽  
Pcr Assay ◽  
Content Type ◽  
E Coli ◽  
Successful Recovery

Timely accurate diagnosis of Shiga toxin-producingEscherichia coli(STEC) infections is important. We evaluated a laboratory-developed real-time PCR (LD-PCR) assay targetingstx1,stx2, andrfbEO157with 2,386 qualifying stool samples submitted to the microbiology laboratory of a tertiary care pediatric center between July 2011 and December 2013. Broth cultures of PCR-positive samples were tested for Shiga toxins by enzyme immunoassay (EIA) (ImmunoCard STAT! enterohemorrhagicE. coli[EHEC]; Meridian Bioscience) and cultured in attempts to recover both O157 and non-O157 STEC.E. coliO157 and non-O157 STEC were detected in 35 and 18 cases, respectively. Hemolytic uremic syndrome (HUS) occurred in 12 patients (10 infected with STEC O157, one infected with STEC O125ac, and one with PCR evidence of STEC but no resulting isolate). Among the 59 PCR-positive STEC specimens from 53 patients, only 29 (54.7%) of the associated specimens were toxin positive by EIA. LD-PCR differentiated STEC O157 from non-O157 usingrfbEO157, and LD-PCR results prompted successful recovery ofE. coliO157 (n= 25) and non-O157 STEC (n= 8) isolates, although the primary cultures and toxin assays were frequently negative. A rapid “mega”-multiplex PCR (FilmArray gastrointestinal panel; BioFire Diagnostics) was used retrospectively, and results correlated with LD-PCR findings in 25 (89%) of the 28 sorbitol-MacConkey agar culture-negative STEC cases. These findings demonstrate that PCR is more sensitive than EIA and/or culture and distinguishes between O157 and non-O157 STEC in clinical samples and thatE. coliO157:H7 remains the predominant cause of HUS in our institution. PCR is highly recommended for rapid diagnosis of pediatric STEC infections.

scholarly journals Distribution of novel Og-types in Shiga toxin-producing Escherichia coli isolated from healthy cattle

2020 ◽  
pp. JCM.02624-20
Author(s):  
Nguyen Thi Thu Huong ◽  
Atsushi Iguchi ◽  
Ritsuko Ohata ◽  
Hisahiro Kawai ◽  
Tadasuke Ooka ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Foodborne Pathogen ◽  
Genomic Analysis ◽  
Epidemiological Studies ◽  
Biosynthesis Gene Cluster ◽  
E Coli ◽  
Shigella Boydii ◽  
Healthy Cattle ◽  
Type Strains

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen. Although most cases of STEC infection in humans are due to O157 and non-O157 serogroups, there are also reports of infection with STEC strains that cannot be serologically classified into any O-serogroup (O-serogroup untypeable, OUT). Recently, it has become clear that even OUT strains can be subclassified based on the diversity of O-antigen biosynthesis gene cluster (O-AGC) sequences. Cattle are thought to be a major reservoir of STEC strains belonging to various serotypes; however, the internal composition of OUT STEC strains in cattle remains unknown. In this study, we screened 366 STEC strains isolated from healthy cattle by using multiplex PCR kits including primers that targeted novel O-AGC types (Og-types) found in OUT E. coli and Shigella strains in previous studies. Interestingly, 94 (25.7%) of these strains could be classified into 13 novel Og-types. Genomic analysis revealed that the results of the in silico serotyping of novel Og-type strains were perfectly consistent with those of the PCR experiment. In addition, it was revealed that a dual Og8+OgSB17-type strain carried two types of O-AGCs from E. coli O8 and Shigella boydii type 17 tandemly inserted at the locus, with both antigens expressed on the cell surface. The results of this comprehensive analysis of cattle-derived STEC strains may help improve our understanding of the strains circulating in the environment. Additionally, the DNA-based serotyping systems used in this study could be used in future epidemiological studies and risk assessments of other STEC strains.

scholarly journals Prevalence of Hemolysin Genes and Comparison ofehxASubtype Patterns in Shiga Toxin-Producing Escherichia coli (STEC) and Non-STEC Strains from Clinical, Food, and Animal Sources

2013 ◽  
Vol 79 (20) ◽  
pp. 6301-6311 ◽  
Author(s):  
Sandra C. Lorenz ◽  
Insook Son ◽  
Anna Maounounen-Laasri ◽  
Andrew Lin ◽  
Markus Fischer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Shiga Toxin ◽  
Phenotypic Expression ◽  
Food Sources ◽  
Polymorphism Analysis ◽  
Subtype C ◽  
Content Type ◽  
E Coli ◽  
Subtype A

ABSTRACTShiga toxin-producingEscherichia coli(STEC) belonging to certain serogroups (e.g., O157 and O26) can cause serious conditions like hemolytic-uremic syndrome (HUS), but other strains might be equally pathogenic. While virulence factors, likestxandeae, have been well studied, little is known about the prevalence of theE. colihemolysin genes (hlyA,ehxA,e-hlyA, andsheA) in association with these factors. Hemolysins are potential virulence factors, andehxAandhlyAhave been associated with human illness, but the significance ofsheAis unknown. Hence, 435E. colistrains belonging to 62 different O serogroups were characterized to investigate gene presence and phenotypic expression of hemolysis. We further investigatedehxAsubtype patterns inE. coliisolates from clinical, animal, and food sources. WhilesheAandehxAwere widely distributed,e-hlyAandhlyAwere rarely found. Most strains (86.7%) were hemolytic, and significantly more hemolytic (95%) than nonhemolytic strains (49%) carriedstxand/oreae(P< 0.0001).ehxAsubtyping, as performed by using PCR in combination with restriction fragment length polymorphism analysis, resulted in six closely related subtypes (>94.2%), with subtypes A/D beingeae-negative STECs and subtypes B, C, E, and Feaepositive. Unexpectedly,ehxAsubtype patterns differed significantly between isolates collected from different sources (P< 0.0001), suggesting that simple linear models of exposure and transmission need modification; animal isolates carried mostly subtypes A/C (39.3%/42.9%), food isolates carried mainly subtype A (81.9%), and clinical isolates carried mainly subtype C (66.4%). Certain O serogroups correlated with particularehxAsubtypes: subtype A with O104, O113, and O8; B exclusively with O157; C with O26, O111, and O121.

scholarly journals Molecular Identification of Virulence Genes of Escherichia coli Isolated from Cow Milk and Its Products in Abuja, Nigeria

2020 ◽  
pp. 11-18
Author(s):  
E. C. Okechukwu ◽  
E. U. Amuta ◽  
G. M. Gberikon ◽  
N. Chima ◽  
B. Yakubu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Virulence Genes ◽  
Foodborne Pathogen ◽  
Cow Milk ◽  
E Coli ◽  
Milk Samples ◽  
The Family ◽  
High Prevalence ◽  
Polymerase Chain

Shiga toxin-producing Escherichia coli have been identified as an emerging foodborne pathogen which portends serious risk to human health. Cow milk and its products are potential sources of shiga toxin-producing Escherichia coli. A relatively small number from the family of shiga toxin-producing Escherichia coli are pathogenic. It becomes necessary that Cow milk and milk products are regularly screened for the presence of virulence genes in microbes. The study aimed to genetically determine the presence of virulence genes that are characteristic of Enterohaemorrhagic E. coli in 600 milk samples. The E. coli isolates were recovered from the milk samples (n=35), biochemically examined and genetically screened for virulence genes by multiplex Polymerase Chain Reaction (PCR). The results of the molecular profiling revealed that (stx2) was detected in 17(60.7%), (hlyA) 11(39.3%) and eae genes 8(28.6%) of the E. coli isolates respectively, while (stx1) was not detected. The results indicated a high prevalence of virulent shiga toxin-producing Escherichia coli in the milk samples. Priority attention should be given to this microbe as it will demand stringent steps in the detection given that they are known to be rigorous in identification.

scholarly journals DiarrhoeagenicEscherichia coliandEscherichia albertiiin Brazil: pathotypes and serotypes over a 6-year period of surveillance

2018 ◽  
Vol 147 ◽  
Author(s):  
E. L. Ori ◽  
E. H. Takagi ◽  
T. S. Andrade ◽  
B. T. Miguel ◽  
M. C. Cergole-Novella ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Active Surveillance ◽  
Shiga Toxin ◽  
Control Strategies ◽  
Clinical Samples ◽  
Haemolytic Uremic Syndrome ◽  
E Coli ◽  
Enteric Diseases ◽  
Uremic Syndrome ◽  
And Control

AbstractDiarrhoeagenicEscherichia coli(DEC) is a leading cause of infectious diarrhoea worldwide. In recent years,Escherichia albertiihas also been implicated as a cause of human enteric diseases. This study describes the occurrence ofE. colipathotypes and serotypes associated with enteric illness and haemolytic uremic syndrome (HUS) isolated in Brazil from 2011 to 2016. Pathotypes isolated included enteropathogenicE. coli(EPEC), enteroaggregativeE. coli(EAEC), enterotoxigenicE. coli(ETEC), enteroinvasiveE. coli(EIEC) and Shiga toxin-producingE. coli(STEC). PCR of stool enrichments for DEC pathotypes was employed, andE. albertiiwas also sought. O:H serotyping was performed on all DEC isolates. A total of 683 DEC and 10E. albertiistrains were isolated from 5047 clinical samples. The frequencies of DEC pathotypes were 52.6% (359/683) for EPEC, 32.5% for EAEC, 6.3% for ETEC, 4.4% for EIEC and 4.2% for STEC. DEC strains occurred in patients from 3 months to 96 years old, but EPEC, EAEC and STEC were most prevalent among children. Both typical and atypical isolates of EPEC and EAEC were recovered and presented great serotype heterogeneity. HUS cases were only associated with STEC serotype O157:H7. TwoE. albertiiisolates belonged to serogroup O113 and one had thestx2f gene. The higher prevalence of atypical EPEC in relation to EAEC in community-acquired diarrhoea in Brazil suggests a shift in the trend of DEC pathotypes circulation as previously EAEC predominated. This is the first report ofE. albertiiisolation from active surveillance. These results highlight the need of continuing DEC andE. albertiisurveillance, as a mean to detect changes in the pattern of pathotypes and serotypes circulation and provide useful information for intervention and control strategies.

scholarly journals Draft Genome Sequences of Shiga Toxin-Producing Escherichia coli O157:H7 Strains Recovered from a Major Production Region for Leafy Greens in California

2019 ◽  
Vol 8 (27) ◽  
Author(s):  
Beatriz Quiñones ◽  
Jaszemyn C. Yambao ◽  
Christopher J. Silva ◽  
Bertram G. Lee
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Draft Genome ◽  
Foodborne Pathogen ◽  
Toxin Gene ◽  
Genome Sequences ◽  
Content Type ◽  
Production Region ◽  
Leafy Greens ◽  
Different Levels

ABSTRACT Shiga toxin-producing Escherichia coli O157:H7 is a foodborne pathogen and is responsible for outbreaks of human gastroenteritis. This report documents the draft genome sequences of nine O157:H7 cattle strains, which were identified to be PCR positive for a Shiga toxin gene but displayed different levels of functional toxin activity.

scholarly journals Role of verocytotoxigenic Escherichia coli in the swine production chain

2015 ◽  
Vol 4 (2) ◽  
Author(s):  
Laura Ercoli ◽  
Silvana Farneti ◽  
David Ranucci ◽  
Stefania Scuota ◽  
Raffaella Branciari
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Clinical Symptoms ◽  
Food Products ◽  
Intestinal Epithelial ◽  
Production Chain ◽  
Pork Products ◽  
Key Factor ◽  
Uremic Syndrome

Shiga toxin-producing <em>Escherichia coli</em> (STEC) can cause severe clinical diseases in humans, such as haemorrhagic colitis (HC) and haemolytic-uremic syndrome (HUS). Although ruminants, primarily cattle, have been suggested as typical reservoirs of STEC, many food products of other origins, including pork products, have been confirmed as vehicles for STEC transmission. Only in rare cases, pork consumption is associated with severe clinical symptoms caused by high pathogenic STEC strains. However, in these outbreaks, it is unknown whether the contamination of food products occurs during swine processing or via cross-contamination from foodstuffs of different sources. In swine, STEC plays an important role in the pathogenesis of oedema disease. In particular a Shiga toxin subtype, named stx2e, it is considered as a key factor involved in the damage of swine endothelial cells. On the contrary, stx2e-producing <em>Escherichia coli</em> has rarely been isolated in humans, and usually only from asymptomatic carriers or from patients with mild symptoms, such as uncomplicated diarrhoea. In fact, the presence of gene stx2e, encoding for stx2e, has rarely been reported in STEC strains that cause HUS. Moreover, stx2e-producing STEC isolated from humans and pigs were found to differ in serogroup, their virulence profile and interaction with intestinal epithelial cells. Because of the limited epidemiologic data of STEC in swine and the increasing role of non-O157 STEC in human illnesses, the relationship between swine STEC and human disease needs to be further investigated.

scholarly journals Draft Genome Sequences of 12 Shiga Toxin-Producing Escherichia coli Strains Isolated from Dairy Cattle in Portugal

2020 ◽  
Vol 9 (38) ◽  
Author(s):  
Gregor Fiedler ◽  
Andressa Ballem ◽  
Erik Brinks ◽  
Carina Almeida ◽  
Charles M. A. P. Franz ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genetic Diversity ◽  
Dairy Cattle ◽  
Shiga Toxin ◽  
Draft Genome ◽  
Foodborne Pathogen ◽  
Genome Sequences ◽  
Content Type ◽  
The North ◽  
Contaminated Food

ABSTRACT Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen transmitted from animals to humans through contaminated food. Cattle are the main reservoir of STEC, but their genetic diversity is still poorly characterized, especially regarding strains isolated in Portugal. We therefore present the draft genomic sequences of 12 STEC strains isolated from cattle in the north of Portugal.

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