Search Results (18)

Background: While most Escherichia coli strains are harmless members of the gastrointestinal microbiota, certain pathogenic variants can cause severe intestinal and extraintestinal diseases. A notable outbreak of E. coli O104:H4, involving both enteroaggregative (EAEC) and enterohemorrhagic (EHEC) strains, occurred in Europe, resulting in symptoms ranging from bloody diarrhea to life-threatening colitis and hemolytic uremic syndrome (HUS). Since treatment options remain limited and have changed little over the past 40 years, there is an urgent need for an effective vaccine. Such a vaccine would offer major public health and economic benefits by preventing severe infections and reducing outbreak-related costs. A multiepitope vaccine approach, enabled by advances in immunoinformatics, offers a promising strategy for targeting HUS-causing E. coli (O104:H4 and O157:H7 serotypes) with minimal disruption to normal microbiota. This study aimed to design an immunogenic multiepitope vaccine (MEV) construct using bioinformatics and immunoinformatic tools. Methods and Results: Comparative proteomic analysis identified 672 proteins unique to E. coli O104:H4, excluding proteins shared with the nonpathogenic E. coli K-12-MG1655 strain and those shorter than 100 amino acids. Subcellular localization (P-SORTb) identified 17 extracellular or outer membrane proteins. Four proteins were selected as vaccine candidates based on transmembrane domains (TMHMM), antigenicity (VaxiJen), and conservation among EHEC strains. Epitope prediction revealed ten B-cell, four cytotoxic T-cell, and three helper T-cell epitopes. Four MEVs with different adjuvants were designed and assessed for solubility, stability, and antigenicity. Structural refinement (GALAXY) and docking studies confirmed strong interaction with Toll-Like Receptor 4 (TLR4). In silico immune simulations (C-ImmSim) indicated robust humoral and cellular immune responses. In Conclusions, the proposed MEV construct demonstrated promising immunogenicity and warrants further validation in experimental models. Full article

Untreated water bodies are critical ecological niches where environmental conditions can drive the adaptive evolution of bacterial populations, enabling them to acquire new traits such as antibiotic-resistance genes. Escherichia coli is typically a commensal bacterium but can evolve into a pathogenic form, known as Diarrheagenic E. coli, responsible for both intestinal and extraintestinal diseases. This study focuses on the characterization of E. coli isolates from water samples collected from the Matasnillo River and the influence of the Juan Díaz Wastewater Treatment Plant (WWTP). While isolates from the Matasnillo River were classified as commensal, 18% of the isolates from the WWTP belonged to either phylogroups D or B2. Pathotype analysis revealed the presence of Entero-Toxigenic and Entero-Hemorrhagic E. coli in the WWTP. Moreover, Matasnillo River isolates exhibited resistance mainly to the quinolone ciprofloxacin, whereas those from the WWTP influent showed resistance to multiple broad-spectrum antibiotics. Sequencing analysis revealed the prevalence of the transmissible quinolone resistance qnrB19 among the Matasnillo River isolates and mutations conferring resistance to quinolone in gyrA, parC, and parE. These findings highlight the importance of monitoring antibiotic-resistant bacterial contamination in both freshwater and wastewater to mitigate the risk of the spread of resistant pathogens and potential epidemic outbreaks. Full article

Background: Enterohemorrhagic Escherichia coli (EHEC) is a considerable public health concern associated with several foodborne outbreaks of bloody diarrhea (BD) and the potentially lethal hemolytic uremic syndrome (HUS), the pathophysiology of which is attributable to the Shiga toxin (Stx) produced by this bacterium. In most patients, supportive treatment will be sufficient; however, in some cases, antibiotic treatment may be necessary. Most antibiotics are not recommended for EHEC infection treatment, particularly those that kill the bacteria, since this triggers the release of Stx in the body, inducing or worsening HUS. Azithromycin, which prevents the release of Stx and is a weaker inducer of the SOS system, has been successfully used to reduce EHEC shedding. It is necessary to identify compounds that eliminate EHEC without inducing Stx release. The use of natural compounds such as curcumin (CUR), a polyphenol derived from turmeric, has been highlighted as an alternative bactericidal treatment approach. Objective: The objective of this study was to establish the effect of CUR and its interactions with selected antibiotics on resistant EHEC O157/H7/EDL933. Methods: Bacterial cultures were exposed to CUR at three different concentrations (110, 220, and 330 µg/mL) and 1.2% DMSO, and the antimicrobial activity of CUR was assessed by measuring the optical density at 600 nm (OD600). The synergy of CUR and the antibiotics was determined with the FIC method. RT-PCR was performed to determine the expression levels of the bla_CTX-M-15, catA1, acrAB-tolC stx2A, and stx2B genes. Results: Our data indicate that CUR did not affect the growth of EHEC, but when combined with the antibiotics, it acted as a bacterial resistance breaker. Synergistic combinations of CUR and cefotaxime or chloramphenicol significantly reduced colony counts. Conclusions: Our findings support the potential of CUR as a sensitizer or in combination therapy against EHEC. Full article

For several decades, recurring outbreaks of human gastrointestinal infections associated with contaminated sprouts have posed an enduring challenge, highlighting the necessity of controlling the etiological agents on contaminated sprout seeds. This study investigated the efficacy of calcium hypochlorite and peroxyacetic acid treatments in inactivating the cells of four enterohemorrhagic Escherichia coli (EHEC) isolates—viz. E. coli O157:H7 K4492, F4546, and H1730, as well as E. coli O104:H4 BAA-2326—on alfalfa seeds and sprouts. The 2–3 log CFU/g of EHEC cells inoculated to sprout seeds became undetectable (≤1.40 log CFU/g) after treatment with the two sanitizers, even with the enrichment steps. Sprouts grown from calcium hypochlorite- and peroxyacetic acid-treated seeds had mean EHEC populations that were 4.54–4.60 log CFU/g and 1.25–1.52 log CFU/g lower, respectively, compared to those on sprouts grown from the untreated control seeds. Significantly (p ≤ 0.05) different from one another, the mean populations of the four EHEC isolates on harvested sprout samples were in the descending order of E. coli O157:H7 K4492, F4546, H1730, and E. coli O104:H4 BAA-2326. The results suggest that both sanitizing treatments effectively suppressed EHEC growth on alfalfa seeds and sprouts, but their effectiveness was bacterial-isolate-dependent. Full article

Contamination of beef by certain strains of Shiga toxin-producing Escherichia coli (STEC) called enterohemorrhagic E. coli (EHEC) can lead to outbreaks of severe disease. Therefore, accurate monitoring tests are needed to identify high risk beef products and divert them from consumers. Most EHEC testing focuses on the detection of their key virulence factors Shiga toxin (stx) and intimin (eae). However, these two factors can occur separately in lower risk nonpathogenic E. coli (STEC and enteropathogenic E. coli; EPEC) and confound testing if both are present. Accessory virulence factors like the Type III secreted effectors espK and espV may aid in increasing the specificity of EHEC testing. This work first evaluated collections of EHEC (n = 83), STEC (n = 100) and EPEC (n = 95), finding espK and/or espV in 100%, 0%, and 60% of each, respectively. Next, an inoculation study of beef trim samples (n = 118) examined the ability of including espK and espV in the monitoring test scheme to distinguish samples inoculated with EHEC from those inoculated with mixtures of STEC and EPEC (non-EHEC). Test accuracy was calculated as Area Under the Receiver Operating Characteristic curve (AUC) and found to be significantly (p < 0.05) different, increasing from 68.0% (stx/eae) to 76.8% by including espK and espV. Finally, 361 regulatory agency beef samples that had been identified as suspect for EHEC (stx+/eae+) were examined with the addition of espK and espV, and results compared to culture isolation. Culture isolation identified 42 EHEC, 82 STEC, and 67 EPEC isolates in 146 of the samples. In the case of these naturally contaminated samples, inclusion of espK and espV increased test accuracy compared to culture isolation from an AUC of 50.5% (random agreement) to 69.8% (good agreement). Results show that the inclusion of espK and espV can increase the specificity of identifying high risk EHEC contaminated beef and release beef contaminated with nonpathogenic or low risk E. coli. Further, use of espK and espV identified samples contaminated by common EHEC of serogroups O157, O26, and O103, as well as of less common serogroups O182, O177, and O5. Full article

Enterohemorrhagic Escherichia coli (EHEC) is a common pathotype of E. coli that causes numerous outbreaks of foodborne illnesses. EHEC is a zoonotic pathogen that is transmitted from animals to humans. Ruminants, particularly cattle, are considered important reservoirs for virulent EHEC strains. Humans can become infected with EHEC through the consumption of contaminated food and water or through direct contact with infected animals or humans. E. coli O157:H7 is one of the most commonly reported causes of foodborne illnesses in developed countries. The formation of attaching and effacing (A/E) lesions on the intestinal epithelium, combined with Shiga toxin production, is a hallmark of EHEC infection and can lead to lethal hemolytic–uremic syndrome (HUS). For the phage-dependent regulation of Shiga toxin production, antibiotic treatment is contraindicated, as it may exacerbate toxin production, limiting therapeutic options to supportive care. In response to this challenge and the growing threat of antibiotic resistance, phytochemicals have emerged as promising antivirulence agents. These plant-derived compounds target bacterial virulence mechanisms without promoting resistance. Therefore, the aim of this study is to summarize the recent knowledge on the use of phytochemicals targeting EHEC. We focused on the molecular basis of their action, targeting the principal virulence determinants of EHEC. Full article

Enterohemorrhagic Escherichia coli (EHEC) outbreaks have been frequently linked to the consumption of produce. Furthermore, produce grown on organic farms possess a higher risk, as the farmers avoid antibiotics and chemicals. This study sets out to evaluate the effectiveness of advanced postharvest disinfection processes using berry pomace extracts (BPEs) in reducing EHEC load in two common leafy greens, spinach and lettuce. Spinach and lettuce were inoculated with ~5 log CFU/leaf EHEC EDL-933 and then treated with three different concentrations of BPE (1, 1.5, and 2 gallic acid equivalent, GAE mg/mL) for increasing periods of time. After the wash, the bacteria were quantified. Changes in the relative expression of virulence genes and the genes involved in cell division and replication and response against stress/antibiotics were studied. We observed a significant reduction in EHEC EDL933, ranging from 0.5 to 1.6 log CFU/spinach leaf (p < 0.05) washed with BPE water. A similar trend of reduction, ranging from 0.3 to 1.3 log CFU/mL, was observed in pre-inoculated lettuce washed with BPE water. We also quantified the remaining bacterial population in the residual treatment solutions and found the survived bacterial cells (~3 log CFU/mL) were low despite repeated washing with the same solution. In addition, we evaluated the phenolic concentration in leftover BPE, which did not change significantly, even after multiple uses. Alterations in gene expression levels were observed, with downregulation ranging from 1 to 3 log folds in the genes responsible for the adhesion and virulence of EHEC EDL933 and significant upregulation of genes responsible for survival against stress. All other genes were upregulated, ranging from 2 to 7 log folds, with a dose-dependent decrease in expression. This finding shows the potential of BPE to be used for sanitation of fresh produce as a natural and sustainable approach. Full article

Outbreaks of Enterohemorrhagic Escherichia coli (EHEC), Salmonella enterica, and Listeria monocytogenes linked to fresh produce consumption pose significant food safety concerns. These pathogens can contaminate pre-harvest produce through various routes, including contaminated water. Soil physicochemical properties and flooding can influence pathogen survival in soils. We investigated survival of EHEC, S. enterica, and L. monocytogenes in soil extracts designed to represent soils with stagnant water. We hypothesized pathogen survival would be influenced by soil extract nutrient levels and the presence of native microbes. A chemical analysis revealed higher levels of total nitrogen, phosphorus, and carbon in high-nutrient soil extracts compared to low-nutrient extracts. Pathogen survival was enhanced in high-nutrient, sterile soil extracts, while the presence of native microbes reduced pathogen numbers. A microbiome analysis showed greater diversity in low-nutrient soil extracts, with distinct microbial compositions between extract types. Our findings highlight the importance of soil nutrient composition and microbial dynamics in influencing pathogen behavior. Given key soil parameters, a long short-term memory model (LSTM) effectively predicted pathogen survival. Integrating these factors can aid in developing predictive models for pathogen persistence in agricultural systems. Overall, our study contributes to understanding the complex interplay in agricultural ecosystems, facilitating informed decision-making for crop production and food safety enhancement. Full article

(1) Background: In recent years, serious disease outbreaks have occurred caused by pathogens like Escherichia coli, Listeria and Salmonella. The EHEC epidemic in 2011, in Germany, caused by enterohemorrhagic E. coli, resulted in the death of about 50 people. This illustrates the potential impact of contaminated food and the associated importance of decontaminating food that can be consumed raw. One possible approach is disinfection using UV radiation, which is a fast and environmentally friendly technique. (2) Methods: The objective of this study is to investigate the germicidal effect of ultraviolet radiation on E. coli × pGLO on bagged lettuce and on chicory seedlings. Irradiation is performed both by a conventional mercury vapor lamp with its 254 nm UV-C emission and, for comparison, with the 222 nm Far-UV-C radiation of a KrCl excimer lamp as in contrast to 254 nm radiation, Far-UV-C-radiation is known to inactivate pathogens without harming humans. (3) Results: For 222 nm radiation, a mean log reduction dose of 7.6 mJ/cm² was found for E. coli on Cichorium intybus var. foliosum seedlings. Similar experimental results were obtained for the packaged lettuce with a 222 nm D90 dose of 12.7 mJ/cm². A mean E. coli log reduction dose of 5.5 mJ/cm² was observed for Valerianella locusta when irradiated at 254 nm. When this wavelength was applied to E. coli on the chicory seedlings, a mean log reduction dose of 3.6 mJ/cm² was determined. The irradiation of the seedlings was more effective than that of the packaged lettuce. Both plants did not show visible damage after irradiation. (4) Conclusions: UV-C radiation seems to be suitable for germ reduction on plants, with 254 nm radiation exhibiting a larger antimicrobial impact than 222 nm radiation for both plants. Full article

Escherichia albertii is an emerging foodborne pathogen. To better understand the pathogenesis and health risk of this pathogen, comparative genomics and phenotypic characterization were applied to assess the pathogenicity potential of E. albertii strains isolated from wild birds in a major agricultural region in California. Shiga toxin genes stx_2f were present in all avian strains. Pangenome analyses of 20 complete genomes revealed a total of 11,249 genes, of which nearly 80% were accessory genes. Both core gene-based phylogenetic and accessory gene-based relatedness analyses consistently grouped the three stx_2f-positive clinical strains with the five avian strains carrying ST7971. Among the three Stx2f-converting prophage integration sites identified, ssrA was the most common one. Besides the locus of enterocyte effacement and type three secretion system, the high pathogenicity island, OI-122, and type six secretion systems were identified. Substantial strain variation in virulence gene repertoire, Shiga toxin production, and cytotoxicity were revealed. Six avian strains exhibited significantly higher cytotoxicity than that of stx_2f-positive E. coli, and three of them exhibited a comparable level of cytotoxicity with that of enterohemorrhagic E. coli outbreak strains, suggesting that wild birds could serve as a reservoir of E. albertii strains with great potential to cause severe diseases in humans. Full article

The consumption of contaminated fresh produce caused outbreaks of enterohemorrhagic (EHEC) Escherichia coli. Agricultural soil might be a reservoir for EHEC strains and represent a contamination source for edible plants. Furthermore, the application of manure as fertilizer is an important contamination route. Thus, the German fertilizer ordinance prohibits the use of manure 12 weeks before crop harvest to avoid pathogen transmission into the food chain. In this study, the survival of E. coli O104:H4 strain C227/11Φcu in soil microenvironments with either diluvial sand or alluvial loam at two temperatures was investigated for more than 12 weeks. It was analyzed whether the addition of cattle manure extends EHEC survival in these microenvironments. The experiments were additionally performed with isogenic ΔrpoS and ΔfliC deletion mutants of C227/11Φcu. The survival of C227/11Φcu was highest at 4 °C, whereas the soil type had a minor influence. The addition of cattle manure increased the survival at 22 °C. Deletion of rpoS significantly decreased the survival period under all cultivation conditions, whereas fliC deletion did not have any influence. The results of our study demonstrate that EHEC C227/11Φcu is able to survive for more than 12 weeks in soil microenvironments and that RpoS is an important determinant for survival. Full article

Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is a form of thrombotic microangiopathy secondary to an infection by an enterohemorrhagic E. coli. Historically considered a pediatric disease, its presentation has been described as typical, with bloody diarrhea at the forefront. However, in adults, the clinical presentation is more diverse and makes the early diagnosis hazardous. In this review, we review the epidemiology, most important outbreaks, physiopathology, clinical presentation and prognosis of STEC-HUS, focusing on the differential features between pediatric and adult disease. We show that the clinical presentation of STEC-HUS in adults is far from typical and marked by the prevalence of neurological symptoms and a poorer prognosis. Of note, we highlight knowledge gaps and the need for studies dedicated to adult patients. The differences between pediatric and adult patients have implications for the treatment of this disease, which remains a public health threat and lack a specific treatment. Full article

Crop plants can become contaminated with human pathogenic bacteria in agro-production systems. Some of the transmission routes of human pathogens to growing plants are well explored such as water, manure and soil, whereas others are less explored such as seeds. Fenugreek seeds contaminated with the entero-hemorrhagic Escherichia coli O104:H4 were suspected to be the principle vectors for transmission of the pathogen to sprouts at the food-borne disease outbreak in Hamburg and surrounding area in 2011. In this study we raised the questions of whether cells of the entero-aggregative E. coli O104:H4 strain 55989 is capable of colonizing developing plants from seeds and if it would be possible that, via plant internalization, these cells can reach the developing embryonic tissue of the next generation of seeds. To address these questions, we followed the fate of strain 55989 and of two other E. coli strains from artificially contaminated seeds to growing plants, and from developing flower tissue to mature seeds upon proximate introductions to the plant reproductive organs. Escherichia coli strains differing in origin, adherence properties to epithelial cells, and virulence profile were used in our experimentation to relate eventual differences in seed and plant colonization to typical E. coli properties. Experiments were conducted under realistic growth circumstances in greenhouse and open field settings. Entero-aggregative E. coli strain 55989 and the two other E. coli strains were able to colonize the root compartment of pea plants from inoculated seeds. In roots and rhizosphere soil, the strains could persist until the senescent stage of plant growth, when seeds had ripened. Colonization of the above-soil parts was only temporary at the start of plant growth for all three E. coli strains and, therefore, the conclusion was drawn that translocation of E. coli cells via the vascular tissue of the stems to developing pea seeds seems unlikely under circumstances realistic for agricultural practices. Proximate introductions of cells of E. coli strains to developing flowers also did not result in internal seed contamination, indicating that internal seed contamination with E. coli is an unlikely event. The fact that all three E. coli strains showed stronger preference for the root-soil zones of growing pea plants than for the above soil plant compartments, in spite of their differences in clinical behaviour and origin, indicate that E. coli in general will colonize root compartments of crop plants in production systems. Full article

Enteroaggregative haemorrhagic Escherichia coli (E. Coli, EAHEC) has been identified as the agent responsible for one of the largest outbreaks of gastroenteritis and Haemolytic-uremic syndrome (HUS) that is transmitted through food in Germany in 2011. The hypervirulent pathotype has a unique combination of two pathogens namely enterohemorrhagic E.coli strain (EHEC) which produces shiga/verotoxin and enteroaggregative E.coli toxins (EAEC) which produces toxins similar to ST and hemolysin. The toxin produced by the EAHEC strain is a hybrid pathotype that combines the virulence potential of the EAEC and EHEC strains that will damage the microcirculation, cause vasculitis and other toxic effects. The purpose of this study was to determine the percentage of samples infected with enteroaggregative hemorrhagic E. coli bacteria (EAHEC) in pediatric diarrhea patients at DR. Soetomo Hospital, Surabaya, Indonesia, 2015. This study used PCR (Polymerase Chain Reaction) method to detect enteroaggregative E. coli strains (CVD432 and aaic genes) and enterohemorrhagic E.coli (eae gene).The results showed that 33 out of 40 (82.5%) stool samples examined were detected enteroaggregative E. coli (EAEC), 4 out of 40 (10%) enterohemorrhagic E. coli (EHEC) and 3 out of 40 (7.5%) enteroaggregative haemorrhagic E. coli bacteria (EAHEC) , which caused diarrhea in pediatric diarrhea patients at Dr. Soetomo General Hospital. The unique combination of genomic features of the Surabaya outbreak strain, containing characteristics from pathotypes EAEC and EHEC, suggested that it represents a new pathotype enteroaggregative haemorrhagic E. coli (EAHEC). It is expected that development of specific primer design and sequencing are needed to continue in this research. Full article

Shiga toxins (Stxs), syn. Vero(cyto)toxins, are potent bacterial exotoxins and the principal virulence factor of enterohemorrhagic Escherichia coli (EHEC), a subset of Shiga toxin-producing E. coli (STEC). EHEC strains, e.g., strains of serovars O157:H7 and O104:H4, may cause individual cases as well as large outbreaks of life-threatening diseases in humans. Stxs primarily exert a ribotoxic activity in the eukaryotic target cells of the mammalian host resulting in rapid protein synthesis inhibition and cell death. Damage of endothelial cells in the kidneys and the central nervous system by Stxs is central in the pathogenesis of hemolytic uremic syndrome (HUS) in humans and edema disease in pigs. Probably even more important, the toxins also are capable of modulating a plethora of essential cellular functions, which eventually disturb intercellular communication. The review aims at providing a comprehensive overview of the current knowledge of the time course and the consecutive steps of Stx/cell interactions at the molecular level. Intervention measures deduced from an in-depth understanding of this molecular interplay may foster our basic understanding of cellular biology and microbial pathogenesis and pave the way to the creation of host-directed active compounds to mitigate the pathological conditions of STEC infections in the mammalian body. Full article