Verocytotoxin-producing Escherichia coli (VTEC)

Cross-sectoral genomic surveillance reveals a lack of insight in sources of human infections with Shiga toxin-producing Escherichia coli, the Netherlands, 2017 to 2023

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen associated with illness ranging from mild diarrhoea to haemolytic uremic syndrome (HUS) or even death. Cross-sectoral data sharing provides an opportunity to gain insight in reservoirs and sources of human infections and starting points for pro-active measures. Nevertheless, phylogenetic clustering of STEC strains from animals, food and human cases is low in the Dutch surveillance system. This is partly due to the substantial contribution of international travel and person-to-person spread in the STEC epidemiology. Furthermore, some STEC strains causing disease in humans may have a human reservoir. Although the main reservoirs and sources are included in the Dutch monitoring programmes, some animals and food products may be under-recognised as potential sources of human infections. More effort in investigating the role of other reservoirs beyond the well-known can provide a better understanding on STEC ecology in general, improving surveillance and source attribution, and ultimately provide better guidance for monitoring and source finding. This also implies having good diagnostics in place and isolates available for typing. Therefore, on the human side of the surveillance, the decision has been made to start isolating STEC at national level.

Characterization of non-O157 enterohemorrhagic Escherichia coli isolated from different sources in Egypt

BACKGROUND

Enterohemorrhagic Escherichia coli (EHEC) O157 is implicated in serious food and water-borne diseases as hemorrhagic colitis (HC), and the potentially fatal hemolytic uremic syndrome (HUS). However, new players of non-O157 EHEC have been implicated in serious infections worldwide. This work aims at analyzing serotype and genotypic-based virulence profile of EHEC local isolates.

METHODS

A total of 335 samples were collected from different sources in Egypt. E. coli was isolated and subjected to serotyping. Non-O157 EHEC isolates were tested for virulence genes using PCR, phenotypic examination, phylogenetic typing, and molecular investigation by ERIC typing and MLST to disclose genetic relatedness of isolates. A heat map was used to identify potential associations between the origin of the isolates, their phenotypic and genotypic characteristics.

RESULTS

A total of 105 out of 335 isolates were identified as E. coli. Surprisingly, 49.5% of these isolates were EHEC, where O111, O91, O26 and O55 were the most prevalent serotypes including 38.46% from stool, 21.15% urine, 23.1% cheese, 9.62% meat products, 3.85% from both yogurt and sewage water. Screening 15 different virulence genes revealed that sheA, stx2 and eae were the most prevalent with abundance rates of 85%, 75% and 36%, respectively. Fifteen profiles of virulence gene association were identified, where the most abundant one was stx2/sheA (19%) followed by stx2/stx2g/sheA/eae (11.5%). Both stx2/sheA/eae and stx2/stx2g/sheA were equally distributed in 9.6% of total isolates. Phylogenetic typing revealed that pathogenic phylogroups B2 and D were detected among clinical isolates only. Forty-six different patterns were detected by ERIC genotyping. MLST resolved three sequence types of ST70, ST120 and ST394. The heat map showed that 21 isolates were of 70% similarity, 9 groups were of 100% clonality.

CONCLUSIONS

The prevalence of non-O157 EHEC pathotype was marginally higher among the food isolates compared to the clinical ones. The endemic ST120 was detected in cheese, necessitating crucial measures to prevent the spread of this clone. Clinical EHEC isolates exhibited a higher score, and combination of virulence genes compared to food and sewage water isolates, thereby posing a significant public health concern.

Intestinal Carriage of Two Distinct stx2f-Carrying Escherichia coli Strains by a Child with Uncomplicated Diarrhea

Two distinct stx2f-carrying Escherichia coli (E. coli) strains, isolated from a child with uncomplicated diarrhea fifteen weeks apart, were characterized by combining short- and long-read sequencing to compare their genetic relatedness. One strain was characterized as Shiga toxin-producing E. coli (STEC)/typical enteropathogenic E. coli (tEPEC) O63:H6 with a repertoire of virulence genes including stx2f, eae (α2-subtype), cdt, and bfpA. The other STEC with serotype O157:H16, reported for the first time as stx2f-carrying Escherichia coli in this study, possessed, in addition, eae (ε-subtype) and cdt, amongst other virulence-related genes. BLAST comparison showed that the stx2f-harboring prophage sequences of both strains were highly homologous (99.6% identity and 96.1% coverage). These results were corroborated by core Stx2f phage Multilocus Sequence Typing (cpMLST) as the stx2f-harboring prophages of both isolates clustered together when compared to those of 167 other human stx2f-carrying Escherichia coli. Overall, the stx2f-harboring prophages of the two distinct E. coli strains isolated from the present case were highly similar, suggesting that the stx2f-harboring phage might have been transferred from the STEC/tEPEC O63:H6 strain to the atypical EPEC (aEPEC) O157:H16 strain in the gut of the child.

Emerging of Shiga toxin-producing Escherichia coli O177:H11 and O177:H25 from cattle at slaughter in Italy

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens frequently carried by cattle, responsible in humans of mild to bloody diarrhoea, haemolytic uraemic syndrome (HUS) and even death. In 2023-2024, a study on STEC contamination of hide and carcasses of dairy cattle at slaughter was planned in Emilia-Romagna region (northern Italy). When the study was still in progress and 60 animals were sampled, the detection of STEC O177 isolates reached high rates and gained our attention. A total of five O177 STEC strains were detected, namely four from three carcasses (5.0 %) and one from a hide sample (1.7 %). The isolates were typed by WGS as following: 1) STEC O177:H11 sequence type (ST) 765 (stx2a+, eae+), detected from one carcass; 2) STEC O177:H25 ST659 (stx2c+, eae+) detected from three carcasses and one hide sample. One carcass was contaminated by both STEC serotypes. The isolates carried other virulence determinants often found in STEC strains associated with HUS, namely the exha, astA and espP genes, together with genes for adhesion to the epithelial cells of the gut (lpfA, fdeC, fimH) and non-Locus for Enterocyte Effacement (LEE) effector protein genes (nleA, nleB). The STEC O177:H11 isolate harboured antimicrobial resistance (AMR) genes to β-lactams (blaTEM-1A), aminoglycosides (aadA1, aph(3″)-Ib, aph(6)-Id), trimethoprim (dfrA1), sulphonamides (sul1, sul2), tetracyclines (tetA), (tetB), streptothricin (sat2), and quaternary ammonium compounds (qacEdelta1). On the contrary, the STEC O177:H25 isolates carried no AMR genes. Persistent carriage of STEC O177:H25 ST659 (stx2c+, eae+) at farm level was assessed by testing animals of the same herd sent to slaughter. Interestingly, the colonies of STEC O177:H11 and STEC O177:H25 had different morphology on CHROMagar™ STEC plates, being mauve and colourless, respectively. Since mauve is the colour STEC colonies commonly have on the CHROMagar™ STEC medium, our findings can help microbiologists in the selection of uncommon serotypes. To the best of our knowledge, this is the first detection of STEC O177 from carcasses and hides of dairy cattle at slaughter. Noteworthy, the STEC-positive hide was classified as "very dirty" thus stressing the need of clean animals entering the slaughter chain, as required by Regulation (EC) No 853/2004. Since STEC O177 has been responsible of HUS in Europe, our data could add information on the source of uncommon serogroups in human infections.

Molecular characterization and antibiotic susceptibility of Shiga toxin- producing Escherichia coli (STEC) isolated from raw milk of dairy bovines in Khyber Pakhtunkhwa, Pakistan

This study investigated the virulence potential and antibiotic susceptibility analysis of non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups, which are significant cause of food borne diseases. A study collected 800 samples of dairy bovine raw milk through various sources, 500 from milk shops, 200 from dairy farms, 26 from milk collection centers, and 74 from street vendors. Using a standard method, E. coli was detected in 321 out of the 800 samples collected. Out of the 321 E. coli-positive samples isolated, 148 were identified as STEC using selective media, specifically Cefixime Tellurite Sorbitol MacConkey's Agar (CT-SMA). Out of the 148 positive samples, 40 were confirmed as STEC non-O157 strains using multiplex PCR, indicating a prevalence of 5% (40 out of 800 samples). STEC isolates were subjected to antimicrobial susceptibility testing, and all isolates were resistant to at least one or more antimicrobials tested through the disk diffusion method, revealed high resistance to Amoxicillin 100%, Ceftriaxone 50%, and Penicillin 44.5%, and notably 44% of the strains exhibited Streptomycin resistance, while Enrofloxacin 55%, Florfenicol 50% and Norfloxacin 44%, demonstrated the highest susceptibility. Out of 40 STEC non-O157, twelve were subjected to Multi Locus Sequence Typing (MLST) sequencing through Illumina Inc. MiSeq platform's next-generation sequencing technology, United States. The genome investigation evidenced the persistence of twelve serotypes H4:O82, H30:O9a, H4:O82, H16:O187, H9:O9, H16:O113, H30:O9, H32:O, H32:O, H32, H32, and H38:O187, linked to the potential infections in humans. Conclusion: STEC isolates showed resistance to multiple antimicrobials, raising concerns for both animal and public health due to widespread use of these drugs in treatment and prevention. The study contributes new insights into monitoring STEC in raw milk, emphasizing the critical role of whole genome sequencing (WGS) for genotyping and sequencing diverse isolates. Still a deficiency in understanding STEC pathogenesis mechanisms, ongoing surveillance is crucial for safeguarding human health and enhancing understanding of STEC genetic characteristics.

Species-level characterization of the core microbiome in healthy dogs using full-length 16S rRNA gene sequencing

Despite considerable interest and research in the canine fecal microbiome, our understanding of its species-level composition remains incomplete, as the majority of studies have only provided genus-level resolution. Here, we used full-length 16S rRNA gene sequencing to characterize the fecal microbiomes of 286 presumed healthy dogs living in homes in North America who are devoid of clinical signs, physical conditions, medication use, and behavioral problems. We identified the bacterial species comprising the core microbiome and investigated whether a dog's sex & neuter status, age, body weight, diet, and geographic region predicted microbiome variation. Our analysis revealed that 23 bacterial species comprised the core microbiome, among them Collinsella intestinalis, Megamonas funiformis, Peptacetobacter hiranonis, Prevotella copri, and Turicibacter sanguinis. The 23 taxa comprised 75% of the microbiome on average. Sterilized females, dogs of intermediate body sizes, and those exclusively fed kibble tended to harbor the most core taxa. Host diet category, geographic region, and body weight predicted microbiome beta-diversity, but the effect sizes were modest. Specifically, the fecal microbiomes of dogs fed kibble were enriched in several core taxa, including C. intestinalis, P. copri, and Holdemanella biformis, compared to those fed raw or cooked food. Conversely, dogs on a raw food diet exhibited higher abundances of Bacteroides vulgatus, Caballeronia sordicola, and Enterococcus faecium, among others. In summary, our study provides novel insights into the species-level composition and drivers of the fecal microbiome in healthy dogs living in homes; however, extrapolation of our findings to different dog populations will require further study.

Evidence for Horizontal Transmission and Recirculation of Shiga Toxin-Producing Escherichia coli in the Beef Production Chain in South Africa Using Whole Genome Sequencing

We used whole genome sequencing (WGS) as an epidemiologic surveillance tool to elucidate the transmission dynamics of Shiga toxin-producing Escherichia coli (STEC) strains along the beef production chain in South Africa. Isolates were obtained from a cattle farm, abattoirs and retail outlets. Isolates were analysed using WGS on a MiSeq platform (Illumina, San Diego, CA, USA) and phylogenetic analysis was carried out. Of the 85 isolates, 39% (33) carried the stx gene and 61% (52) had lost the stx gene. The prevalence of stx subtypes was as follows; stx1a 55% (18/33), stx1b 52% (17/33), stx2a 55% (18/33), stx2b 27% (9/33), stx2dB 30% (10/33) and stx2d1A 15% (5/33). Thirty-five different serogenotypes were detected, of which 65% (56) were flagellar H-antigens and 34% (29) were both O-antigens and flagellar H-antigens. We identified 50 different sequence types (STs), and only nine of the isolates were assigned to three different clonal complexes. Core genome phylogenetic analysis revealed genetic relatedness, and isolates clustered mainly according to their STs and serogenotypes regardless of stx subtypes. This study provides evidence of horizontal transmission and recirculation of STEC strains in Gauteng province and demonstrates that every stage of the beef production chain plays a significant role in STEC entry into the food chain.

How to Improve Surveillance Program for Shiga Toxin-Producing E. coli (STEC): Gap Analysis and Pilot Study

Several pathotypes of enteric E. coli have been identified. The group represented by Shiga toxin-producing E. coli (STEC) is of particular interest. Raw milk and raw milk products are significant sources of STEC infection in humans; therefore, identifying pathogens at the herd level is crucial for public health. Most national surveillance programs focus solely on raw milk and raw milk cheeses that are ready for retail sale, neglecting the possibility of evaluating the source of contamination directly at the beginning of the dairy chain. To assess the viability of the application of new molecular methodologies to STEC identification in raw milk filters and in calf feces, we analyzed 290 samples from 18 different dairy herds, including 88 bulk tank milk (BTM), 104 raw milk filters (RMF), and 98 calf feces samples. In total 3.4% of BTM, 41.4% of RMF, and 73.4% of calves' feces were positive for stx, supporting our hypothesis that BTM is not a suitable matrix to assess the presence of STEC at herd level, underestimating it. Our conclusion is that the surveillance program needs critical and extensive improvements such as RMF and calves' feces analysis implementation to be more efficient in detecting and preventing STEC infections. The epidemiology of these infections and the characteristics of the pathogen clearly show how a One Health approach will be pivotal in improving our capabilities to control the spread of these infections.

Proportions and Serogroups of Enterohemorrhagic Shiga Toxin-producing Escherichia coli in Feces of Fed and Cull Beef and Cull Dairy Cattle at Harvest

Cattle are considered a primary reservoir of Shiga toxin (stx)-producing Escherichia coli that cause enterohemorrhagic disease (EHEC), and contaminated beef products are one vehicle of transmission to humans. However, animals entering the beef harvest process originate from differing production systems: feedlots, dairies, and beef breeding herds. The objective of this study was to determine if fed cattle, cull dairy, and or cull beef cattle carry differing proportions and serogroups of EHEC at harvest. Feces were collected via rectoanal mucosal swabs (RAMSs) from 1,039 fed cattle, 1,058 cull dairy cattle, and 1,018 cull beef cattle at harvest plants in seven U.S. states (CA, GA, NE, PA, TX, WA, and WI). The proportion of the stx gene in feces of fed cattle (99.04%) was not significantly different (P > 0.05) than in the feces of cull dairy (92.06%) and cull beef (91.85%) cattle. When two additional factors predictive of EHEC (intimin and ecf1 genes) were considered, EHEC was significantly greater (P < 0.05) in fed cattle (77.29%) than in cull dairy (47.54%) and cull beef (38.51%) cattle. The presence of E. coli O157:H7 and five common non-O157 EHEC of serogroups O26, O103, O111, O121, and O145 was determined using molecular analysis for single nucleotide polymorphisms (SNPs) followed by culture isolation. SNP analysis identified 23.48%, 17.67%, and 10.81% and culture isolation confirmed 2.98%, 3.31%, and 3.00% of fed, cull dairy, and cull beef cattle feces to contain one of these EHEC, respectively. The most common serogroups confirmed by culture isolation were O157, O103, and O26. Potential EHEC of fourteen other serogroups were isolated as well, from 4.86%, 2.46%, and 2.01% of fed, cull dairy, and cull beef cattle feces, respectively; with the most common being serogroups O177, O74, O98, and O84. The identification of particular EHEC serogroups in different types of cattle at harvest may offer opportunities to improve food safety risk management.

CobB-mediated deacetylation of the chaperone CesA regulates Escherichia coli O157:H7 virulence

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a common food-borne pathogen that can cause acute diseases. Lysine acetylation is a post-translational modification (PTM) that occurs in various prokaryotes and is regulated by CobB, the only deacetylase found in bacteria. Here, we demonstrated that CobB plays an important role in the virulence of EHEC O157:H7 and that deletion of cobB significantly decreased the intestinal colonization ability of bacteria. Using acetylation proteomic studies, we systematically identified several proteins that could be regulated by CobB in EHEC O157:H7. Among these CobB substrates, we found that acetylation at the K44 site of CesA, a chaperone for the type-III secretion system (T3SS) translocator protein EspA, weakens its binding to EspA, thereby reducing the stability of this virulence factor; this PTM ultimately attenuating the virulence of EHEC O157:H7. Furthermore, we showed that deacetylation of the K44 site, which is deacetylated by CobB, promotes the interaction between CesA and EspA, thereby increasing bacterial virulence in vitro and in animal experiments. In summary, we showed that acetylation influences the virulence of EHEC O157:H7, and uncovered the mechanism by which CobB contributes to bacterial virulence based on the regulation of CesA deacetylation.

[Modern concept of differential diagnosis of colitis: from G.F. Lang to the present day. A review]

The aim of the article is to improve the differential diagnosis of specific and nonspecific inflammatory bowel diseases. In Russia, this scientific direction is associated with the name of G.F. Lang, who performed in 1901-1902 the study "On ulcerative inflammation of the large intestine caused by balantidiasis". The etiology of specific colitis is associated with infection with parasites, bacteria and viruses that cause inflammation of the intestinal wall, diarrhea, often with an admixture of mucus, pus and blood. Specific colitis (SC) may be accompanied by fever, abdominal pain, and tenesmus. Bacterial colitis is commonly caused by Salmonella, Shigella, Escherichia coli, Clostridium difficile, Campylobacter jejuni, Yersinia enterocolitica, and Mycobacterium tuberculosis. Viral colitis is caused by rotavirus, adenovirus, cytomegalovirus, and norovirus. Parasitic colitis can be caused by Entamoeba histolytica and balantidia. In gay people, SC can cause sexually transmitted infections: Neisseria gonorrhoeae, Chlamydia trachomatis, and treponema pallidum, affecting the rectum. Stool microscopy, culture, and endoscopy are used to establish the diagnosis. Stool culture helps in the diagnosis of bacterial colitis in 50% of patients, and endoscopic studies reveal only nonspecific pathological changes. Differential diagnosis of SC should be carried out with immune-inflammatory bowel diseases (ulcerative colitis, Crohn's disease, undifferentiated colitis), radiation colitis and other iatrogenic bowel lesions. The principles of diagnosis and therapy of inflammatory bowel diseases associated with various etiological.

Antimicrobial and Mycotoxin Reducing Properties of Lactic Acid Bacteria and Their Influence on Blood and Feces Parameters of Newborn Calves

The aim of this study was to evaluate the influence of in acid whey (AW) multiplied Lactiplantibacillus plantarum LUHS135 (L.pl135), Lacticaseibacillus paracasei LUHS244 (L.pc244), and their biomass combination on newborn calves' feces and blood parameters. Additionally, the antimicrobial and mycotoxin-reducing properties and the resistance to antibiotics of the tested lactic acid bacteria (LAB) strains were analyzed. In order to ensure effective biomass growth in AW, technological parameters for the supplement preparation were selected. Control calves were fed with a standard milk replacer (SMR) and treated groups (from the 2nd day of life until the 14th day) were supplemented with 50 mL of AWL.pl135, AWL.pc244, and AWL.pl135×L.pc244 (25 mL AWL.pl135 + 25 mL AWL.pc244) in addition to SMR. It was established that L.pl135 and L.pc244 possess broad antimicrobial activities, are non-resistant to the tested antibiotics, and reduce mycotoxin concentrations in vitro. The optimal duration established for biomass growth was 48 h (LAB count higher than 7.00 log10 CFU mL-1 was found after 48 h of AW fermentation). It was established that additional feeding of newborn calves with AWL.pl135, AWL.pc244, and AWL.pl135×L.pc244 increased lactobacilli (on average by 7.4%), and AWL.pl135 and AWL.pc244 reduced the numbers of Enterobacteriaceae in calves' feces. The tested supplements also reduced the lactate concentration (on average, by 42.5%) in calves' blood. Finally, the tested supplements had a positive influence on certain health parameters of newborn calves; however, further research is needed to validate the mechanisms of the beneficial effects.

Focal Active Colitis: What Are Its Clinical Implications? A Narrative Review

Focal active colitis (FAC) is described as a histolopathological term indicating the isolated finding of focal neutrophil infiltration in the colonic crypts. Currently, there exist numerous debates regarding the clinical significance of diagnosing FAC, which may or may not have clinical relevance as it is frequently detected in colorectal biopsies without any other microscopic abnormalities. The objective of this narrative review is to provide an overview of the available evidence concerning the clinical implications of FAC, both in the adult population (among five studies available in the scientific literature) and in the pediatric context (based on two available studies).

Escherichia coli O157:H7 strains in bovine carcasses and the impact on the animal production chain

Foodborne diseases are characterized by conditions that can induce symptomatic illnesses in their carriers, and therefore represent a serious problem. They are important conditions from a clinical and epidemiological point of view, and are associated with the occurrence of serious public health problems, with a strong impact on morbidity and mortality. The Escherichia coli (E. coli) is an enterobacterium associated with enteric conditions of variable intensity and which are accompanied by blood. The transmission routes are mainly based on the consumption of contaminated food and water sources. Shiga toxin-producing E. coli (STEC) are considered a serogroup of E. coli, are capable of producing Shiga-type toxins (Stx 1 and Stx 2) and the O157:H7 strain is one of the best-known serotypes. The early detection of this pathogen is very important, especially due to the capacity of contamination of carcasses destined for food consumption and supply of productive markets. Sanitary protocols must be developed and constantly reviewed in order to prevent/control the presence of the pathogen.

Study of Zoonotic Pathogens in Alien Population of Veiled Chameleons (Chamaeleo calyptratus) in the Canary Islands (Spain)

Veiled chameleons (Chamaeleo calyptratus) are native to the Arabian Peninsula that have been introduced as pets in many regions around the world, such as the Canary Islands (Spain). In this work, the gastrointestinal content from veiled chameleons of Gran Canaria island (Canary Islands) has been analyzed to determine the presence of zoonotic bacteria. Forty animals were analyzed using different selective culture media and PCR. The most isolated bacteria were Yersinia enterocolitica (52.4%), followed by Salmonella spp. (40.0%), with positive isolates for Salmonella Tyhpi and Salmonella Typhimurium. Pseudomonas spp. was found in 32.5% of the chameleons. More than half were positive for Pseudomonas aeruginosa. Antibiotic-resistant Staphylococcus spp. was detected in six animals plus one isolate of non-resistant Staphylococcus hominis. Multiple mycobacteria species belonging to both tuberculous and non-tuberculous complexes were identified as well as Escherichia coli carrying the stx₁ and eae virulence genes with 12.5% and 7.5% prevalence, respectively. Listeria monocytogenes, Campylobacter spp., and Vibrio spp. were found in lower proportion (<5%). The results obtained indicate that veiled chameleons in Gran Canaria could be playing a role in the maintenance and dissemination of the pathogens detected, harming public health and biodiversity.

Intestinal organoids: A versatile platform for modeling gastrointestinal diseases and monitoring epigenetic alterations

Considering the significant limitations of conventional 2D cell cultures and tissue in vitro models, creating intestinal organoids has burgeoned as an ideal option to recapitulate the heterogeneity of the native intestinal epithelium. Intestinal organoids can be developed from either tissue-resident adult stem cells (ADSs) or pluripotent stem cells (PSCs) in both forms induced PSCs and embryonic stem cells. Here, we review current advances in the development of intestinal organoids that have led to a better recapitulation of the complexity, physiology, morphology, function, and microenvironment of the intestine. We discuss current applications of intestinal organoids with an emphasis on disease modeling. In particular, we point out recent studies on SARS-CoV-2 infection in human intestinal organoids. We also discuss the less explored application of intestinal organoids in epigenetics by highlighting the role of epigenetic modifications in intestinal development, homeostasis, and diseases, and subsequently the power of organoids in mirroring the regulatory role of epigenetic mechanisms in these conditions and introducing novel predictive/diagnostic biomarkers. Finally, we propose 3D organoid models to evaluate the effects of novel epigenetic drugs (epi-drugs) on the treatment of GI diseases where epigenetic mechanisms play a key role in disease development and progression, particularly in colorectal cancer treatment and epigenetically acquired drug resistance.

Optimized Bioorthogonal Non-canonical Amino Acid Tagging to Identify Serotype-Specific Biomarkers in Verotoxigenic Escherichia coli

According to Canada's Food Report Card 2016, there are 4 million foodborne illnesses acquired each year in the nation alone. The leading causes of foodborne illness are pathogenic bacteria such as shigatoxigenic/verotoxigenic Escherichia coli (STEC/VTEC) and Listeria monocytogenes. Most current detection methods used to identify these bacterial pathogens are limited in their validity since they are not specific to detecting metabolically active organisms, potentially generating false-positive results from non-living or non-viable bacteria. Previously, our lab developed an optimized bioorthogonal non-canonical amino acid tagging (BONCAT) method which allows for the labeling of translationally active wild-type pathogenic bacteria. Incorporation of homopropargyl glycine (HPG) into the cellular surfaces of bacteria allows for protein tagging using the bioorthogonal alkyne handle to report on the presence of pathogenic bacteria. Here, we use proteomics to identify more than 400 proteins differentially detected by BONCAT between at least two of five different VTEC serotypes. These findings pave the way for future examination of these proteins as biomarkers in BONCAT-utilizing assays.

Boundaries That Prevent or May Lead Animals to be Reservoirs of Escherichia coli O104:H4

Escherichia coli O104:H4, a hybrid serotype carrying virulence factors from enteroaggregative (EAEC) and Shiga toxin-producing (STEC) pathotypes, is the reported cause of a multicountry outbreak in 2011. Evaluation of potential routes of human contamination revealed that this strain is a foodborne pathogen. In contrast to STEC strains, whose main reservoir is cattle, serotype O104:H4 has not been commonly isolated from animals or related environments, suggesting an inability to naturally colonize the gut in hosts other than humans. However, contrary to this view, this strain has been shown to colonize the intestines of experimental animals in infectious studies. In this minireview, we provide a systematic summary of reports highlighting potential evolutionary changes that could facilitate the colonization of new reservoirs by these bacteria.

Disease Occurrence in- and the Transferal of Zoonotic Agents by North American Feedlot Cattle

North America is a large producer of beef and contains approximately 12% of the world's cattle inventory. Feedlots are an integral part of modern cattle production in North America, producing a high-quality, wholesome protein food for humans. Cattle, during their final stage, are fed readily digestible high-energy density rations in feedlots. Cattle in feedlots are susceptible to certain zoonotic diseases that impact cattle health, growth performance, and carcass characteristics, as well as human health. Diseases are often transferred amongst pen-mates, but they can also originate from the environment and be spread by vectors or fomites. Pathogen carriage in the gastrointestinal tract of cattle often leads to direct or indirect contamination of foods and the feedlot environment. This leads to the recirculation of these pathogens that have fecal-oral transmission within a feedlot cattle population for an extended time. Salmonella, Shiga toxin-producing Escherichia coli, and Campylobacter are commonly associated with animal-derived foods and can be transferred to humans through several routes such as contact with infected cattle and the consumption of contaminated meat. Brucellosis, anthrax, and leptospirosis, significant but neglected zoonotic diseases with debilitating impacts on human and animal health, are also discussed.

GlnH, a Novel Antigen That Offers Partial Protection against Verocytotoxigenic Escherichia coli Infection

Verotoxin-producing Escherichia coli (VTEC) causes zoonotic infections, with potentially devastating complications, and children under 5 years old are particularly susceptible. Antibiotic treatment is contraindicated, and due to the high proportion of infected children that suffer from severe and life-changing complications, there is an unmet need for a vaccine to prevent VTEC infections. Bacterial adhesins represent promising candidates for the successful development of a vaccine against VTEC. Using a proteomic approach to identify bacterial proteins interacting with human gastrointestinal epithelial Caco-2 and HT-29 cells, we identified eleven proteins by mass spectrometry. These included a glutamine-binding periplasmic protein, GlnH, a member of the ABC transporter family. The glnH gene was identified in 13 of the 15 bovine and all 5 human patient samples tested, suggesting that it is prevalent. We confirmed that GlnH is involved in the host cell attachment of an O157:H7 prototype E. coli strain to gastrointestinal cells in vitro. Recombinant GlnH was expressed and purified prior to the immunisation of mice. When alum was used as an adjuvant, GlnH was highly immunogenic, stimulating strong serological responses in immunised mice, and it resulted in a modest reduction in faecal shedding but did not reduce colonisation. GlnH immunisation with a T-cell-inducing adjuvant (SAS) also showed comparable antibody responses and an IgG1/IgG2a ratio suggestive of a mixed Th1/Th2 response but was partially protective, with a 1.5-log reduction in colonisation of the colon and caecum at 7 days relative to the adjuvant only (p = 0.0280). It is clear that future VTEC vaccine developments should consider the contribution of adjuvants in addition to antigens. Moreover, it is likely that a combined cellular and humoral response may prove more beneficial in providing protective interventions against VTEC.

Tunable Magneto-Plasmonic Nanosensor for Sensitive Detection of Foodborne Pathogens

Frequent outbreaks of food-borne pathogens, particularly E. coli O157:H7, continue to impact human health and the agricultural economy tremendously. The required cell count for this pathogenic strain of E. coli O157:H7 is relatively low and hence it is vital to detect at low colony forming unit (CFU) counts. Available detection methods, though sensitive, fall short in terms of timeliness and often require extensive sample processing. To overcome these limitations, we propose a novel magneto-plasmonic nanosensor (MPnS) by integrating surface plasmon resonance (SPR) properties with spin-spin magnetic relaxation (T2 MR) technology. We engineered MPnS by encapsulating several gold nanoparticles (GNPs) within the polymer-coating of iron oxide nanoparticles (IONPs). First, the polyacrylic acid (PAA)-coated IONPs were synthesized using a solvent precipitation method, then gold chloride solution was used to synthesize GNPs and encapsulate them within the PAA-coatings of IONPs in one step. A magnetic separation technique was used to purify the MPnS and the presence of GNPs within IONPs was characterized using transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and other spectroscopic methods. The synthesized MPnS exhibits MR relaxation properties while possessing amplified optical properties than conventional GNPs. This allows for rapid and ultrasensitive detection of E. coli O157:H7 by SPR, T2 MR, and colorimetric readout. Experiments conducted in simple buffer and in milk as a complex media demonstrated that our MPnS-based assay could detect as low as 10 CFUs of this pathogenic strain of E. coli O157:H7 in minutes with no cross-reactivity. Overall, the formulated MPnS is robust and holds great potential for the ultrasensitive detection of E. coli O157:H7 in a simple and timely fashion. Moreover, this platform is highly customizable and can be used for the detection of other foodborne pathogens.

Spatiotemporal dynamics of Escherichia coli presence and magnitude across a national groundwater monitoring network, Republic of Ireland, 2011-2020

Groundwater is a vital drinking water resource and its protection from microbiological contamination is paramount to safeguard public health. The Republic of Ireland (RoI) is characterised by the highest incidence of verocytotoxigenic Escherichia coli (VTEC) enteritis in the European Union (EU), linked to high reliance on unregulated groundwater sources (~16% of the population). Yet, the spatio-temporal factors influencing the frequency and magnitude of microbial contamination remain largely unknown, with past studies typically constrained to spatio-temporally 'limited' sampling campaigns. Accordingly, the current investigation sought to analyse an extensive spatially distributed time-series (2011-2020) of groundwater monitoring data in the RoI. The dataset, compiled by the Environmental Protection Agency (EPA), showed 'high' contamination rates, with 66.7% (88/132) of supplies testing positive for E. coli, and 29.5% (39/132) exceeding concentrations of 10MPN/100 ml (i.e. gross contamination) at least once during the 10-year monitoring period. Seasonal decomposition analyses indicate that E. coli detection rates peak during late autumn/early winter, coinciding with increases in annual rainfall, while gross contamination peaks in spring (May) and late-summer (August), likely reflecting seasonal shifts in agricultural practices. Mixed effects logistic regression modelling indicates that monitoring sources located in karst limestone are statistically associated with E. coli presence (OR = 2.76, p = 0.03) and gross contamination (OR = 2.54, p = 0.037) when compared to poorly productive aquifers (i.e., transmissivity below 10m²/d). Moreover, 5-day and 30-day antecedent rainfall increased the likelihood of E. coli contamination (OR = 1.027, p < 0.001 and OR = 1.005, p = 0.016, respectively), with the former also being associated with gross contamination (OR = 1.042, p < 0.001). As such, it is inferred that preferential flow and direct ingress of surface runoff are the most likely ingress mechanisms associated with E. coli groundwater supply contamination. The results presented are expected to inform policy change around groundwater source protection and provide insight for the development of groundwater monitoring programmes in geologically heterogeneous regions.

Examining the role of person-to-person transmission during a verocytotoxigenic Escherichia coli outbreak in Ontario, Canada

OBJECTIVE

Person-to-person transmission can occur during outbreaks of verotoxigenic Escherichia coli (VTEC), however the impact of this transmission route is not well understood. This study aimed to examine the role of person-to-person transmission during a VTEC outbreak, and how targeting this route may reduce outbreak size. A deterministic compartmental model describing a VTEC outbreak was constructed and fit to data from a 2008 outbreak in Ontario, Canada. Using the best-fit model, simulations were run to calculate the: reduction in transmission rate after implementing interventions, proportion of cases infected through both transmission routes, and number of cases prevented by interventions. Latin hypercube sensitivity analysis was conducted to examine the sensitivity of the outbreak size to the model parameters.

RESULTS

Based on the best-fit model, ~ 14.25% of the cases likely arose due to person-to-person transmission. Interventions reduced this transmission rate by ~ 73%, causing a reduction in outbreak size of ~ 17% (47 cases). Sensitivity analysis showed that the model was highly sensitive to changes in all parameters of the model. The model demonstrates that person-to-person could be an important transmission route during VTEC outbreaks. Targeting this route of transmission through hand hygiene and work exclusions could reduce the final outbreak size.

Shiga Toxin-Producing Escherichia coli and Milk Fat Globules

Shiga toxin-producing Escherichia coli (STEC) are zoonotic Gram-negative bacteria. While raw milk cheese consumption is healthful, contamination with pathogens such as STEC can occur due to poor hygiene practices at the farm level. STEC infections cause mild to serious symptoms in humans. The raw milk cheese-making process concentrates certain milk macromolecules such as proteins and milk fat globules (MFGs), allowing the intrinsic beneficial and pathogenic microflora to continue to thrive. MFGs are surrounded by a biological membrane, the milk fat globule membrane (MFGM), which has a globally positive health effect, including inhibition of pathogen adhesion. In this review, we provide an update on the adhesion between STEC and raw MFGs and highlight the consequences of this interaction in terms of food safety, pathogen detection, and therapeutic development.

Selected Livestock-Associated Zoonoses as a Growing Challenge for Public Health

The aim of this paper is to review the most significant livestock-associated zoonoses. Human and animal health are intimately connected. This idea has been known for more than a century but now it has gained special importance because of the increasing threat from zoonoses. Zoonosis is defined as any infection naturally transmissible from vertebrate animals to humans. As the frequency and prevalence of zoonotic diseases increase worldwide, they become a real threat to public health. In addition, many of the newly discovered diseases have a zoonotic origin. Due to globalization and urbanization, some of these diseases have already spread all over the world, caused by the international flow of goods, people, and animals. However, special attention should be paid to farm animals since, apart from the direct contact, humans consume their products, such as meat, eggs, and milk. Therefore, zoonoses such as salmonellosis, campylobacteriosis, tuberculosis, swine and avian influenza, Q fever, brucellosis, STEC infections, and listeriosis are crucial for both veterinary and human medicine. Consequently, in the suspicion of any zoonoses outbreak, the medical and veterinary services should closely cooperate to protect the public health.

Innovative Treatments Enhancing the Functionality of Gut Microbiota to Improve Quality and Microbiological Safety of Foods of Animal Origin

The gastrointestinal tract, or gut, microbiota is a microbial community containing a variety of microorganisms colonizing throughout the gut that plays a crucial role in animal health, growth performance, and welfare. The gut microbiota is closely associated with the quality and microbiological safety of foods and food products originating from animals. The gut microbiota of the host can be modulated and enhanced in ways that improve the quality and safety of foods of animal origin. Probiotics—also known as direct-fed microbials—competitive exclusion cultures, prebiotics, and synbiotics have been utilized to achieve this goal. Reducing foodborne pathogen colonization in the gut prior to slaughter and enhancing the chemical, nutritional, or sensory characteristics of foods (e.g., meat, milk, and eggs) are two of many positive outcomes derived from the use of these competitive enhancement–based treatments in food-producing animals.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Rapid Detection of Single Viable Escherichia coli O157 Cells in Fresh Lettuce and Strawberry by Immunomagnetic Flow Cytometry in Combination with Pre-Enrichment

Enterohemorrhagic Escherichia coli are an important pathogen causing food poisoning. The rapid detection of viable E. coli O157 in vegetables and fruits at single-cell level is critical because of the low infective dose of this pathogen. In this study, an immunomagnetic flow cytometry (IMFC)-based method was developed to detect E. coli O157 in lettuce and strawberries inoculated with 1 CFU/25 g. This method developed immunomagnetic (IM)-beads to capture E. coli O157 cells. The pre-enrichment of E. coli O157 and IM-bead separation rapidly increased the concentration of cells to a detectable range for flow cytometry. Compared with the plate-based method, the diagnostic sensitivity and specificity of the IMFC-based method were 100% in 166 samples, including 100 artificially contaminated samples, 60 retail samples, and six O157-positive samples for proficiency testing. The developed IMFC-based method was found to be effective in detecting E. coli O157 at single-cell level in 25 g of lettuce or strawberry with relatively shorter associated time to results of 5.7 h. Therefore, the IMFC-based method could improve detection efficiency and also make early warnings in a short time.

Chemical Composition and Antibacterial Activity of the Lippia origanoides Kunth Essential Oil from the Carajás National Forest, Brazil

Species of the genus Lippia are rich in essential oils and have shown antibacterial properties, which may be related to oils' chemical composition. The present work aimed to evaluate the antimicrobial potential of Lippia origanoides Kunth against two bacteria strains: Escherichia coli and Staphylococcus aureus. Leaf essential oils were obtained by hydrodistillation in a modified Clevenger-type apparatus, and their chemical composition was determined by gas chromatography coupled to mass spectrometry (GC/MS) and flame ionization detection (GC/FID). We identified 28 compounds, representing 98.87% of the total concentration of the essential oil. The compounds identified at the highest concentrations were 1,8-cineole (35.04%), carvacrol (11.32%), p-cymene (8.53%), α-pinene (7.17%), and γ-terpinene (7.16%). The leaf essential oil of L. origanoides showed antibacterial action on biological isolates of Escherichia coli and Staphylococcus aureus. For Escherichia coli, the oil presented bactericidal action at concentrations of 5-20 μL/mL. Regarding Staphylococcus aureus, the bactericidal effect was noted at 20 μL/mL and the bacteriostatic action was noted around 2.5-10 μL/mL. Given the results obtained, L. origanoides essential oil showed promising biological potential against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, thus encouraging further studies on substances isolated from this species to contribute to the development of new antimicrobial drugs.

Genetic features of verotoxigenic Escherichia coli O157:H7 isolated from clinical cases of Argentina and Chile

We aimed to compare the genetic diversity existing in VTEC O157:H7 strains isolated from cases of human disease from Argentina and Chile. For it, 76 strains were studied in relation to the distribution of genes encoding virulence factors and subtyped by lineage-specific polymorphisms (LSPA-6), and phylogroups assignment. Our results show the almost exclusive circulation of VTEC O157:H7 isolates belonging to lineage I/II, associated with hypervirulent strains, and to the phylogroup E and, on the other hand, genetic diversity present among Argentinean and Chilean strains analyzed, mainly in relation to putative virulence determinants and nle profiles.

Spatiotemporal Dynamics of Sporadic Shiga Toxin-Producing Escherichia coli Enteritis, Ireland, 2013-2017

The Republic of Ireland regularly reports the highest annual crude incidence rates of Shiga toxin–producing Escherichia coli (STEC) enteritis in the European Union, ≈10 times the average. We investigated spatiotemporal patterns of STEC enteritis in Ireland using multiple statistical tools. Overall, we georeferenced 2,755 cases of infection during January 2013–December 2017; we found >1 case notified in 2,340 (12.6%) of 18,641 Census Small Areas. We encountered the highest case numbers in children 0–5 years of age (n = 1,101, 39.6%) and associated with serogroups O26 (n = 800, 29%) and O157 (n = 638, 23.2%). Overall, we identified 17 space-time clusters, ranging from 2 (2014) to 5 (2017) clusters of sporadic infection per year; we detected recurrent clustering in 3 distinct geographic regions in the west and mid-west, all of which are primarily rural. Our findings can be used to enable targeted epidemiologic intervention and surveillance.

Molecular detection of Shiga toxin-producing Escherichia coli (STEC) O157 in sheep, goats, cows and buffaloes

BACKGROUND

Shiga toxin-producing E. coli (STEC) are important foodborne pathogens that causing serious public health consequences worldwide. The present study aimed to estimate the prevalence ratio and to identify the zoonotic potential of E. coli O157 isolates in slaughtered adult sheep, goats, cows and buffaloes.

MATERIALS AND METHODS

A total of 400 Recto-anal samples were collected from two targeted sites Rawalpindi and Islamabad. Among them, 200 samples were collected from the slaughterhouse of Rawalpindi included sheep (n = 75) and goats (n = 125). While, 200 samples were collected from the slaughterhouse of Islamabad included cows (n = 120) and buffalos (n = 80). All samples were initially processed in buffered peptone water and then amplified by conventional PCR. Samples positive for E. coli O157 were then streaked onto SMAC media plates. From each positive sample, six different Sorbitol fermented pink-colored colonies were isolated and analyzed again via conventional PCR to confirm the presence of rfbE O157 gene. Isolates positive for rfbE O157 gene were then further analyzed by multiplex PCR for the presence of STEC other virulent genes (sxt1, stx2, eae and ehlyA) simultaneously.

RESULTS

Of 400 RAJ samples only 2 (0.5%) showed positive results for E. coli O157 gene, included sheep 1/75 (1.33%) and buffalo 1/80 (1.25%). However, goats (n = 125) and cows (n = 120) found negative for E. coli O157. Only 2 isolates from each positive sample of sheep (1/6) and buffalo (1/6) harbored rfbE O157 genes, while five isolates could not. The rfbE O157 isolate (01) of sheep sample did not carry any of STEC genes, while the rfbE O157 isolate (01) of buffalo sample carried sxt1, stx2, eae and ehlyA genes simultaneously.

CONCLUSION

It was concluded that healthy adult sheep and buffalo are possibly essential carriers of STEC O157. However, rfbE O157 isolate of buffalo RAJ sample carried 4 STEC virulent genes, hence considered an important source of STEC infection to humans and environment which should need to devise proper control systems.

High Occurrence of Shiga Toxin-Producing Escherichia coli in Raw Meat-Based Diets for Companion Animals-A Public Health Issue

Feeding pets raw meat-based diets (RMBDs) is becoming increasingly popular but comes with a risk of pathogenic bacteria, including Shiga toxin-producing Escherichia coli (STEC). In humans, STEC may cause gastrointestinal illnesses, including diarrhea, hemorrhagic colitis (HC), and the hemolytic uremic syndrome (HUS). The aim of this study was to evaluate commercially available RMBDs with regard to the occurrence of STEC. Of 59 RMBD samples, 59% tested positive by real-time PCR for the presence of Shiga toxin genes stx1 and/or stx2. STECs were recovered from 41% of the 59 samples, and strains were subjected to serotyping and virulence gene profiling, using whole genome sequencing (WGS)-based methods. Of 28 strains, 29% carried stx2a or stx2d, which are linked to STEC with high pathogenic potential. Twenty different serotypes were identified, including STEC O26:H11, O91:H10, O91:H14, O145:H28, O146:H21, and O146:H28, which are within the most common non-O157 serogroups associated with human STEC-related illnesses worldwide. Considering the low infectious dose and potential severity of disease manifestations, the high occurrence of STEC in RMBDs poses an important health risk for persons handling raw pet food and persons with close contact to pets fed on RMBDs, and is of concern in the field of public health.

Antimicrobial Effects of Aqueous Extract from Calyces of Hibiscus sabdariffa in CD-1 Mice Infected with Multidrug-Resistant Enterohemorrhagic Escherichia coli and Salmonella Typhimurium

To determinate the antimicrobial effect of chloramphenicol and aqueous extract against multidrug-resistant enterohemorrhagic Escherichia coli (EHEC) and Salmonella enterica serovar Typhimurium in CD-1 mice. Aqueous extract was isolated from Hibiscus sabdariffa calyces. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of chloramphenicol and aqueous extract were determined for EHEC and S. Typhimurium. Nine groups of six mice each were formed. Three groups were inoculated orally with 1 × 10⁴ colony-forming units (CFU) of S. Typhimurium, three groups were inoculated with 1 × 10⁴ CFU of EHEC and the remaining three groups were not inoculated. Six hours postinoculation, the mice of some groups were orally administered solutions of aqueous extract (50 mg/mL), chloramphenicol (82 μg/mL), or isotonic saline. The EHEC and S. Typhimurium concentration in all mice feces was determined. For both pathogens, the MIC and MBC values of aqueous extract were 20 y 50 mg/mL, respectively; for chloramphenicol, they were between 17.5 and 82 μg/mL. EHEC and S. Typhimurium were not detected in the feces of mice that were administered aqueous extract on the 2nd and 3rd days posttreatment. Furthermore, these mice recovered from the infection. In contrast, in mice not treated, or treated with chloramphenicol alone, pathogens were isolated from their feces throughout the study, and some mice died. The H. sabdariffa calyx extracts could be an alternative to control multidrug-resistant bacteria in humans and animals.

Shiga Toxin-Producing Escherichia coli in Wheat Grains: Detection and Isolation by Polymerase Chain Reaction and Culture Methods

Shiga toxin-producing Escherichia coli (STEC) are major foodborne pathogens and seven serogroups, O26, O45, O103, O111, O121, O145, and O157, often called top-7 STEC, account for the majority of the STEC-associated human illnesses in the United States. Two Shiga toxins, Shiga toxins 1 and 2, encoded by stx1 and stx2 genes, are major virulence factors that are involved in STEC infections. Foodborne STEC infections have been linked to a variety of foods of both animal and plant origin, including products derived from cereal grains. In recent years, a few STEC outbreaks have been linked to contaminated wheat flour. The microbiological quality of the wheat grains is a major contributor to the safety of wheat flour. The objective of the study was to utilize polymerase chain reaction (PCR)- and culture-based methods to detect and isolate STEC in wheat grains. Wheat grain samples (n = 625), collected from different regions of the United States, were enriched in modified buffered peptone water with pyruvate (mBPWp) or E. coli (EC) broth, and they were then subjected to PCR- and culture-based methods to detect and isolate STEC. Wheat grains enriched in EC broth yielded more samples positive for stx genes (1.6% vs. 0.32%) and STEC serogroups (5.8% vs. 2.4%) than mBPWp. The four serogroups of top-7 detected and isolated were O26, O45, O103, and O157 and none of the isolates was positive for the Shiga toxin genes. A total of five isolates that carried the stx2 gene were isolated and identified as serogroups O8 (0.6%) and O130 (0.2%). The EC broth was a better medium to enrich wheat grains than mBPWp for the detection and isolation of STEC. The overall prevalence of virulence genes and STEC serogroups in wheat grains was low. The stx2-positive serogroups isolated, O8 and O130, are not major STEC pathogens and have only been implicated in sporadic infections in animals and humans.

Optimization of Notification Criteria for Shiga Toxin-Producing Escherichia coli Surveillance, the Netherlands

We describe the consequences of 2 major changes in notification criteria for Shiga toxin–producing Escherichia coli surveillance in the Netherlands. The change to reporting acute, more severe infections appears to be a good compromise between workload, redundancy, and public health relevance, provided isolates remain available for typing and sequencing.

Severely ill pediatric patients with Shiga toxin-associated hemolytic uremic syndrome (STEC-HUS) who suffered from multiple organ involvement in the early stage

BACKGROUND

Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is the main cause of pediatric acute kidney injury (AKI) in Argentina. Endothelial injury is the trigger event in the microangiopathic process. The host inflammatory response to toxin and E. coli lipopolysaccharide (LPS) is involved in disease pathophysiology.

METHODS

This retrospective study describes pediatric STEC-HUS patients with multiorgan involvement at the initial phase of disease. A retrospective study of critically ill HUS patients with evidence of E. coli infection was conducted through a period of 15 years.

RESULTS

Forty-four patients 35.4 ± 4.1 months were admitted to the intensive care unit for 21 ± 2 days. Mechanical ventilation was required in 41 patients, early inotropic support in 37, and 28 developed septic shock. Forty-one patients required kidney replacement therapy for 12 ± 1 days. Forty-one patients showed neurological dysfunction. Dilated cardiomyopathy was demonstrated in 3 patients, left ventricular systolic dysfunction in 4, and hypertension in 17. Four patients had pulmonary hemorrhage, and acute respiratory distress syndrome in 2. Colectomy for transmural colonic necrosis was performed in 3 patients. Thirty-seven patients were treated with therapeutic plasma exchange, and 28 patients received methylprednisolone (10 mg/kg for 3 days). Of the surviving 32 patients, neurological sequelae were seen in 11 and chronic kidney failure in 5.

CONCLUSIONS

Severe clinical outcome at onset suggests an amplified inflammatory response after exposure to Shiga toxin and/or E. coli LPS. STEC-HUS associated with severe neurological involvement, hemodynamic instability, and AKI requires intensive care and focused therapy.

Insights into Emergence of Antibiotic Resistance in Acid-Adapted Enterohaemorrhagic Escherichia coli

The emergence of multidrug-resistant pathogens presents a global challenge for treating and preventing disease spread through zoonotic transmission. The water and foodborne Enterohaemorrhagic Escherichia coli (EHEC) are capable of causing intestinal and systemic diseases. The root cause of the emergence of these strains is their metabolic adaptation to environmental stressors, especially acidic pH. Acid treatment is desired to kill pathogens, but the protective mechanisms employed by EHECs cross-protect against antimicrobial peptides and thus facilitate opportunities for survival and pathogenesis. In this review, we have discussed the correlation between acid tolerance and antibiotic resistance, highlighting the identification of novel targets for potential production of antimicrobial therapeutics. We have also summarized the molecular mechanisms used by acid-adapted EHECs, such as the two-component response systems mediating structural modifications, competitive inhibition, and efflux activation that facilitate cross-protection against antimicrobial compounds. Moving beyond the descriptive studies, this review highlights low pH stress as an emerging player in the development of cross-protection against antimicrobial agents. We have also described potential gene targets for innovative therapeutic approaches to overcome the risk of multidrug-resistant diseases in healthcare and industry.

Identification, Shiga toxin subtypes and prevalence of minor serogroups of Shiga toxin-producing Escherichia coli in feedlot cattle feces

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens that cause illnesses in humans ranging from mild to hemorrhagic enteritis with complications of hemolytic uremic syndrome and even death. Cattle are a major reservoir of STEC, which reside in the hindgut and are shed in the feces, a major source of food and water contaminations. Seven serogroups, O26, O45, O103, O111, O121, O145 and O157, called ‘top-7’, are responsible for the majority of human STEC infections in North America. Additionally, 151 serogroups of E. coli are known to carry Shiga toxin genes (stx). Not much is known about fecal shedding and prevalence and virulence potential of STEC other than the top-7. Our primary objectives were to identify serogroups of STEC strains, other than the top-7, isolated from cattle feces and subtype stx genes to assess their virulence potential. Additional objective was to develop and validate a novel multiplex PCR assay to detect and determine prevalence of six serogroups, O2, O74, O109, O131, O168, and O171, in cattle feces. A total of 351 strains, positive for stx gene and negative for the top-7 serogroups, isolated from feedlot cattle feces were used in the study. Of the 351 strains, 291 belonged to 16 serogroups and 60 could not be serogrouped. Among the 351 strains, 63 (17.9%) carried stx1 gene and 300 (82.1%) carried stx2, including 12 strains positive for both. The majority of the stx1 and stx2 were of stx1a (47/63; 74.6%) and stx2a subtypes (234/300; 78%), respectively, which are often associated with human infections. A novel multiplex PCR assay developed and validated to detect six serogroups, O2, O74, O109, O131, O168, and O171, which accounted for 86.9% of the STEC strains identified, was utilized to determine their prevalence in fecal samples (n = 576) collected from a commercial feedlot. Four serogroups, O2, O109, O168, and O171 were identified as the dominant serogroups prevalent in cattle feces. In conclusion, cattle shed in the feces a number of STEC serogroups, other than the top-7, and the majority of the strains isolated possessed stx2, particularly of the subtype 2a, suggesting their potential risk to cause human infections.

Designing of a chimeric protein contains StxB, intimin and EscC against toxicity and adherence of enterohemorrhagic Escherichia coli O157:H7 and evaluation of serum antibody titers against it

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain is known as one of the major human foodborne pathogens. Lack of effective clinical treatment for human diarrheal diseases confirms the need for vaccine production against enteric bacteria such as E.coli O157:H7. Shiga-like toxin (Stx), EscC, and Intimin are the main important virulent factors of this enteric pathogen. In the present study, a comparative Omics analysis was conducted to identify most invasion EHEC antigenic factors as a potential immunogen. SEI (Stx-EscC-Intimin) trivalent chimeric protein was designed from the exposed and epitope rich part of these virulence factors. Sequence optimization, physicochemical properties, mRNA folding, three-dimensional structure and immunoinformatics data were investigated. The chimeric gene was synthesized with codon bias of E. coli. Recombinant protein was expressed and confirmed by western blot analysis. To evaluate the immunogenicity of the designed protein, the protein was administered to BALB/c mice and the serum IgG was determined by ELISA. Based on the Ramachandran plot, the validation data showed that 90.1 % of residues lie in the favored region. The high antigenicity of the multimeric protein was predicted by the immunoinformatic analysis. Epitope prediction had shown the proper distribution of linear and conformational B-cell epitopes and the competition of T-cell epitopes to bind MHC molecules too. Recombinant ESI Protein with 74.5 kDa was expressed in E. coli. Western blot analysis by anti-Stx antibody, confirmed a single band of chimeric protein. Consequently, the chimeric gene was designed and constructed after assessments. From in silico approach, the protein deduced from this cassette can be an immunogen candidate, and act against toxicity and adherence of EHEC.

Occurrence and Antibiogram of Escherichia coli O157 : H7 in Raw Beef and Hygienic Practices in Abattoir and Retailer Shops in Ambo Town, Ethiopia

Foodborne infections are widespread and growing public health problems in the world. Shiga toxin-producing Escherichia coli O157 : H7 is one of the most significant foodborne pathogens. This study was conducted to assess the occurrence and antibiogram of E. coli O157 : H7 from raw beef as well as hygienic and sanitary practices of meat handling in abattoir and retailer shops. Systematic random sampling technique and census methods were used to collect samples from abattoir and retailer shops, respectively. All tryptone soya broth preenriched carcass samples were subcultured onto MacConkey agar. Then, the bacterium confirmed as Escherichia coli using biochemical tests was streaked onto Sorbitol-MacConkey agar and incubated at 37°C for 24 hrs. Escherichia coli O157 : H7 was confirmed by latex agglutination kit. In vitro antimicrobial susceptibility test of Escherichia coli O157 : H7 isolates was done against 13 antimicrobials. Hygiene and sanitation data were collected using a pretested structured questionnaire and observational checklist. Pearson Chi-square and Fisher's exact two-tailed tests were performed and differences were considered significant at P ≤ 0.05. Out of 197 meat samples, 23.4% (95% confidence interval (CI): 17.6-29.9%) and 9.1% (95% CI: 5.5-14.1%) were contaminated with Escherichia coli and Escherichia coli O157 : H7, respectively. There was a significant variation in the occurrence of Escherichia coli O157 : H7 between retailer shops (19.1%) and abattoir (7.2%) (P = 0.03). The study revealed that the municipal abattoir and retailer shops in Ambo town did not adhere to the required sanitation and hygienic standards. All Escherichia coli O157 : H7 isolates were susceptible to norfloxacin, sulfamethoxazole-trimethoprim, chloramphenicol, and ceftazidime. However, all isolates were resistant to amoxicillin. Multidrug resistance was widespread and was found in 66.3% of Escherichia coli O157 : H7 isolates. The occurrence of Escherichia coli O157 : H7 was high. Therefore, fulfilling national and international meat safety requirements, training and monitoring of meat handlers, and rational use of antimicrobials are recommended.

Chemically synthesized Gb3 glycosphingolipids: tools to access their function in lipid membranes

Gb3 glycosphingolipids are the specific receptors for bacterial Shiga toxin. Whereas the trisaccharidic head group of Gb3 defines the specificity of Shiga toxin binding, the lipophilic part composed of sphingosine and different fatty acids is suggested to determine its localization within membranes impacting membrane organisation and protein binding eventually leading to protein internalisation. While most studies use Gb3 extracts, chemical synthesis provides a unique tool to access different tailor-made Gb3 glycosphingolipids. In this review, strategies to synthesize these complex glycosphingolipids are presented. Special emphasis is put on the preparation of Gb3 molecules differing only in their fatty acid part (saturated, unsaturated, α-hydroxylated and both, unsaturated and α-hydroxylated). With these molecules in hand, it became possible to investigate the phase behaviour of liquid ordered/liquid disordered supported membranes doped with the Gb3 species by means of fluorescence and atomic force microscopy. The results clearly highlight the influence of the different fatty acids of the Gb3 sphingolipids on the phase behaviour and the binding properties of Shiga toxin B subunits, even though the membranes were only doped with 5 mol% of the receptor lipid. To obtain fluorescent Gb3 derivatives, either fatty acid labelled Gb3 molecules or head group labelled ones were synthesized. These molecules enabled us to address the question, where the Gb3 sphingolipids are localized prior protein binding by means of fluorescence microscopy on giant unilamellar vesicles. The results again demonstrate that the fatty acid of Gb3 plays a pivotal role for the overall membrane organisation.

Extracellular Vesicles and Renal Endothelial Cells: A Fatal Attraction in Hemolytic Uremic Syndrome

This review focuses on typical hemolytic uremic syndrome (HUS), a life-threatening sequela of human infections caused, particularly in children, by Shiga toxin-producing Escherichia coli strains. Thrombotic microangiopathy of the brain and the kidney is the end point of toxin action, resulting in the hallmarks of HUS (ie, thrombocytopenia, anemia, and acute renal failure). A growing body of evidence points to the role of extracellular vesicles released in the blood of patients by toxin-challenged circulating cells (monocytes, neutrophils, and erythrocytes) and platelets, as a key factor in the pathogenesis of HUS. This review provides i) an updated description of the pathogenesis of Shiga toxin-producing E. coli infections; ii) an analysis of blood cell-derived extracellular vesicles, and of their parent cells, as triggering factors in HUS; and iii) a model explaining why Shiga toxin-containing vesicles dock preferentially to the endothelia of target organs.

Integrating evolutionary aspects into dual-use discussion: the cases of influenza virus and enterohemorrhagic Escherichia coli

Research in infection biology aims to understand the complex nature of host–pathogen interactions. While this knowledge facilitates strategies for preventing and treating diseases, it can also be intentionally misused to cause harm. Such dual-use risk is potentially high for highly pathogenic microbes such as Risk Group-3 (RG3) bacteria and RG4 viruses, which could be used in bioterrorism attacks. However, other pathogens such as influenza virus (IV) and enterohemorrhagic Escherichia coli (EHEC), usually classified as RG2 pathogens, also demonstrate high dual-use risk. As the currently approved therapeutics against these pathogens are not satisfactorily effective, previous outbreaks of these pathogens caused enormous public fear, media attention and economic burden. In this interdisciplinary review, we summarize the current perspectives of dual-use research on IV and EHEC, and further highlight the dual-use risk associated with evolutionary experiments with these infectious pathogens. We support the need to carry out experiments pertaining to pathogen evolution, including to gain predictive insights on their evolutionary trajectories, which cannot be otherwise achieved with stand-alone theoretical models and epidemiological data. However, we also advocate for increased awareness and assessment strategies to better quantify the risks-versus-benefits associated with such evolutionary experiments. In addition to building public trust in dual-use research, we propose that these approaches can be extended to other pathogens currently classified as low risk, but bearing high dual-use potential, given the particular pressing nature of their rapid evolutionary potential.

Antibiotic Resistance in Shiga Toxigenic Escherichia coli Isolates from Surface Waters and Sediments in a Mixed Use Urban Agricultural Landscape

Antibiotic resistance (AR) phenotypes and acquired resistance determinants (ARDs) detected by in silico analysis of genome sequences were examined in 55 Shiga toxin-producing Escherichia coli (STEC) isolates representing diverse serotypes recovered from surfaces waters and sediments in a mixed use urban/agricultural landscape in British Columbia, Canada. The isolates displayed decreased susceptibility to florfenicol (65.5%), chloramphenicol (7.3%), tetracycline (52.7%), ampicillin (49.1%), streptomycin (34.5%), kanamycin (20.0%), gentamycin (10.9%), amikacin (1.8%), amoxicillin/clavulanic acid (21.8%), ceftiofur (18.2%), ceftriaxone (3.6%), trimethoprim-sulfamethoxazole (12.7%), and cefoxitin (3.6%). All surface water and sediment isolates were susceptible to ciprofloxacin, nalidixic acid, ertapenem, imipenem and meropenem. Eight isolates (14.6%) were multidrug resistant. ARDs conferring resistance to phenicols (floR), trimethoprim (dfrA), sulfonamides (sul1/2), tetracyclines (tetA/B), and aminoglycosides (aadA and aph) were detected. Additionally, narrow-spectrum β-lactamase blaTEM-1b and extended-spectrum AmpC β-lactamase (cephalosporinase) blaCMY-2 were detected in the genomes, as were replicons from plasmid incompatibility groups IncFII, IncB/O/K/Z, IncQ1, IncX1, IncY and Col156. A comparison with surveillance data revealed that AR phenotypes and ARDs were comparable to those reported in generic E. coli from food animals. Aquatic environments in the region are potential reservoirs for the maintenance and transmission of antibiotic resistant STEC, associated ARDs and their plasmids.