Hemolytic uremic syndrome due to Shiga toxin-producing Escherichia coli infection

Clinical Outcomes and Virulence Factors of Shiga Toxin-Producing Escherichia coli (STEC) from Southern Alberta, Canada, from 2020 to 2022

Shiga toxin-producing Escherichia coli (STEC) can cause severe clinical disease in humans, particularly in young children. Recent advances have led to greater availability of sequencing technologies. We sought to use whole genome sequencing data to identify the presence or absence of known virulence factors in all clinical isolates submitted to our laboratory from Southern Alberta dated 2020-2022 and correlate these virulence factors with clinical outcomes obtained through chart review. Overall, the majority of HUS and hospitalizations were seen in patients with O157:H7 serotypes, and HUS cases were primarily in young children. The frequency of virulence factors differed between O157:H7 and non-O157 serotypes. Within the O157:H7 cases, certain virulence factors, including espP, espX1, and katP, were more frequent in HUS cases. The number of samples was too low to determine statistical significance.

Practical approach to thrombocytopenia in patients with sepsis: a narrative review

Thrombocytopenia frequently occurs in patients with sepsis. Disseminated intravascular coagulation (DIC) may be a possible cause of thrombocytopenia owing to its high prevalence and association with poor outcomes; however, it is important to keep the presence of other diseases in mind in sepsis practice. Thrombotic microangiopathy (TMA), which is characterized by thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (HUS), and complement-mediated HUS, is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ damage. TMA has become widely recognized in recent years because of the development of specific treatments. Previous studies have reported a remarkably lower prevalence of TMA than DIC; however, its epidemiology is not well defined, and there may be cases in which TMA is not correctly diagnosed, resulting in poor outcomes. Therefore, it is important to differentiate DIC from TMA. Nevertheless, differentiating between DIC and TMA remains a challenge as indicated by previous reports that most patients with TMA can be diagnosed as DIC using the universal coagulation scoring system. Several algorithms to differentiate sepsis-related DIC from TMA have been suggested, contributing to improving the care of septic patients with thrombocytopenia; however, it may be difficult to apply these algorithms to patients with coexisting DIC and TMA, which has recently been reported. This review describes the disease characteristics, including epidemiology, pathophysiology, and treatment, of DIC, TMA, and other diseases with thrombocytopenia and proposes a novel practical approach flow, which is characterized by the initiation of the diagnosis of TMA in parallel with the diagnosis of DIC. This practical flow also refers to the longitudinal diagnosis and treatment flow with TMA in mind and real clinical timeframes. In conclusion, we aim to widely disseminate the results of this review that emphasize the importance of incorporating consideration of TMA in the management of septic DIC. We anticipate that this practical new approach for the diagnostic and treatment flow will lead to the appropriate diagnosis and treatment of complex cases, improve patient outcomes, and generate new epidemiological evidence regarding TMA.

Shiga Toxin-Producing Escherichia coli Isolated from Wild Ruminants in Liguria, North-West Italy

Wildlife may represent an important source of infectious diseases for humans and other wild and domestic animals. Wild ruminants can harbour and transmit Shiga toxin-producing Escherichia coli (STEC) to humans, and some strains even carry important antimicrobial resistance. In this study, 289 livers of wild roe deer, fallow deer, red deer and chamois collected in Liguria, north-west Italy, from 2019 to 2023 were analysed. Overall, 44 STEC strains were isolated from 28 samples. The characterisation of serogroups showed the presence of O104, O113, O145 and O146 serogroups, although for 28 colonies, the serogroup could not be determined. The most prevalent Shiga toxin gene in isolated strains was Stx2, and more specifically the subtype Stx2b. The other retrieved subtypes were Stx1a, Stx1c, Stx1d and Stx2g. The isolated strains generally proved to be susceptible to the tested antimicrobials. However, multi-drug resistances against highly critical antimicrobials were found in one strain isolated from a roe deer. This study highlights the importance of wildlife monitoring in the context of a "One Health" approach.

Vacation in Egypt associated with Shiga toxin-producing Escherichia coli infection in children and adolescents, northern Italy, 2023

BackgroundHaemolytic uremic syndrome (HUS) is a severe complication of infection with Shiga toxin-producing Escherichia coli (STEC). Although the reservoirs of STEC are known, the source of the infection of sporadic cases is often unknown. In 2023, we observed several cases of bloody diarrhoea with STEC infection in children and adolescents returning from vacations.AimWe aimed to explore the association between travel and bloody diarrhoea with STEC infection in children and adolescents.MethodsWe included all children and adolescents with bloody diarrhoea with STEC infection identified in 2023 by the ItalKid-HUS Network surveillance system in northern Italy. We interviewed children's families and sent a questionnaire on recent travels abroad. The exposure time was between 3 days after arrival abroad and 5 days after return home. A self-controlled case series (SCCS) design was used in the analysis.ResultsOf the 43 cases, 11 developed HUS. Twenty-three cases did not travel abroad, while 20 had travelled to several destinations. The incidence rate ratio (IRR) associated with travel to Egypt was 88.6 (95% confidence interval (CI): 17.0-462). Serotype analysis excluded the possibility of a single strain causing the infections. We did not find the source of the infections.ConclusionThere is an elevated risk of acquiring STEC infection with bloody diarrhoea and HUS associated with travel to Egypt. Specific investigations to identify the source are needed to implement effective preventive measures.

Gastrointestinal involvement in STEC-associated hemolytic uremic syndrome: 10 years in a pediatric center

BACKGROUND

The gastrointestinal (GI) tract represents one of the main targets of typical hemolytic uremic syndrome (HUS) in children. In this observational study, we tried to establish (1) the main features of GI complications during STEC-HUS and (2) the relationship between Escherichia coli serotypes and Shiga toxin (Stx) variants with hepatopancreatic involvement.

METHODS

A total of 79 STEC-HUS patients were admitted to our pediatric nephrology department between January 2012 and June 2021. Evidence of intestinal, hepatobiliary, and pancreatic involvements was reported for each patient, alongside demographic, clinical, and laboratory features. Frequency of gastrointestinal complications across groups of patients infected by specific E. coli serotypes and Stx gene variants was evaluated.

RESULTS

Six patients developed a bowel complication: two developed rectal prolapse, and four developed bowel perforation which resulted in death for three of them and in bowel stenosis in one patient. Acute pancreatitis was diagnosed in 13 patients. An isolated increase in pancreatic enzymes and/or liver transaminases was observed in 41 and 15 patients, respectively. Biliary sludge was detected in three, cholelithiasis in one. Forty-seven patients developed direct hyperbilirubinemia. Neither E. coli serotypes nor Shiga toxin variants correlated with hepatic or pancreatic involvement.

CONCLUSIONS

During STEC-HUS, GI complications are common, ranging from self-limited elevation of laboratory markers to bowel perforation, a severe complication with a relevant impact on morbidity and mortality. Hepatopancreatic involvement is frequent, but usually short-lasting and self-limiting.

Shiga Toxin-Producing Escherichia coli Testing in New York 2011-2022 Reveals Increase in Non-O157 Identifications

Shiga toxin-producing Escherichia coli (STEC) are an important cause of bacterial enteric infection. STEC strains cause serious human gastrointestinal disease, which may result in life-threatening complications such as hemolytic uremic syndrome. They have the potential to impact public health due to diagnostic challenges of identifying non-O157 strains in the clinical laboratory. The Wadsworth Center (WC), the public health laboratory of the New York State Department of Health, has isolated and identified non-O157 STEC for decades. A shift from initially available enzyme immunoassay testing to culture-independent diagnostic tests (CIDTs) has increased the uptake of testing at clinical microbiology laboratories. This testing change has resulted in an increased number of specimen submissions to WC. During a 12-year period between 2011 and 2022, WC received 5037 broths and/or stool specimens for STEC confirmation from clinical microbiology laboratories. Of these, 3992 were positive for Shiga toxin genes (stx1 and/or stx2) by real-time PCR. Furthermore, culture methods were utilized to isolate, identify, and characterize 2925 STEC from these primary specimens. Notably, WC observed a >200% increase in the number of STEC specimens received in 2021-2022 compared with 2011-2012 and an 18% increase in the number of non-O157 STEC identified using the same methodologies. During the past decade, the WC testing algorithm has been updated to manage the increase in specimens received, while also navigating the novel COVID-19 pandemic, which took priority over other testing for a period of time. This report summarizes updated methods for confirmation, surveillance, and outbreak detection of STEC and describes findings that may be related to our algorithm updates and the increased use of CIDTs, which is starting to elucidate the true incidence of non-O157 STEC.

Pathogenic Factors and Recent Study on the Rapid Detection of Shiga Toxin-Producing Escherichia coli (STEC)

This comprehensive review delves into the pathogenicity and detection of Shiga Toxin-Producing Escherichia coli (STEC), shedding light on its various genetic and clinical manifestations. STEC originating from E. coli acquires pathogenicity through mobility and genetic elements. The pathogenicity of STEC is explored in terms of clinical progression, complications, and key toxins such as Shiga toxin (Stx). Stx1 and Stx2 are two distinct Stx types exhibiting different toxicities, with Stx2 often associated with severe diseases. This review also delves into Subtilase cytotoxin, an additional cytotoxin produced by some STEC strains. Pathogenic mechanisms of STEC, such as attaching and effacing intestinal lesions, are discussed, with a focus on roles of genetic factors. Plasmids in STEC can confer unique pathogenicity. Hybridization with other pathogenic E. coli can create more lethal pathogens. This review covers a range of detection methods, ranging from DNA amplification to antigen detection techniques, emphasizing the need for innovative approaches to improve the sensitivity and speed of STEC diagnosis. In conclusion, understanding diverse aspects of STEC pathogenicity and exploring enhanced diagnostic methods are critical to addressing this foodborne pathogen effectively. Pathology of Shiga toxin toxicity. STEC-derived Shiga toxin consists of one A subunit and five B subunits. Pathological symptoms of the disease can progress to HUS within two weeks after the onset of diarrhea. Shiga toxin intoxication is also associated with many complications, such as neurological and cardiac complications. This figure was reconstructed based on data from Bruyand et al.

Prevalence, antibiotic resistance, and virulence gene profile of Escherichia coli strains shared between food and other sources in Africa: A systematic review

Background and Aim

Foodborne diseases caused by Escherichia coli are prevalent globally. Treatment is challenging due to antibiotic resistance in bacteria, except for foodborne infections due to Shiga toxin-producing E. coli, for which treatment is symptomatic. Several studies have been conducted in Africa on antibiotic resistance of E. coli isolated from several sources. The prevalence and distribution of resistant pathogenic E. coli isolated from food, human, and animal sources and environmental samples and their virulence gene profiles were systematically reviewed.

Materials and Methods

Bibliographic searches were performed using four databases. Research articles published between 2000 and 2022 on antibiotic susceptibility and virulence gene profile of E. coli isolated from food and other sources were selected.

Results

In total, 64 articles were selected from 14 African countries: 45% of the studies were conducted on food, 34% on animal samples, 21% on human disease surveillance, and 13% on environmental samples. According to these studies, E. coli is resistant to ~50 antimicrobial agents, multidrug-resistant, and can transmit at least 37 types of virulence genes. Polymerase chain reaction was used to characterize E. coli and determine virulence genes.

Conclusion

A significant variation in epidemiological data was noticed within countries, authors, and sources (settings). These results can be used as an updated database for monitoring E. coli resistance in Africa. More studies using state-of-the-art equipment are needed to determine all resistance and virulence genes in pathogenic E. coli isolated in Africa.

The role of pneumococcal extracellular vesicles on the pathophysiology of the kidney disease hemolytic uremic syndrome

Streptococcus pneumoniae-induced hemolytic uremic syndrome (Sp-HUS) is a kidney disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. This disease is frequently underdiagnosed and its pathophysiology is poorly understood. In this work, we compared clinical strains, isolated from infant Sp-HUS patients, with a reference pathogenic strain D39, for host cytotoxicity and further explored the role of Sp-derived extracellular vesicles (EVs) in the pathogenesis of an HUS infection. In comparison with the wild-type strain, pneumococcal HUS strains caused significant lysis of human erythrocytes and increased the release of hydrogen peroxide. Isolated Sp-HUS EVs were characterized by performing dynamic light-scattering microscopy and proteomic analysis. Sp-HUS strain released EVs at a constant concentration during growth, yet the size of the EVs varied and several subpopulations emerged at later time points. The cargo of the Sp-HUS EVs included several virulence factors at high abundance, i.e., the ribosomal subunit assembly factor BipA, the pneumococcal surface protein A, the lytic enzyme LytC, several sugar utilization, and fatty acid synthesis proteins. Sp-HUS EVs strongly downregulated the expression of the endothelial surface marker platelet endothelial cell adhesion molecule-1 and were internalized by human endothelial cells. Sp-HUS EVs elicited the release of pro-inflammatory cytokines (interleukin [IL]-1β, IL-6) and chemokines (CCL2, CCL3, CXCL1) by human monocytes. These findings shed new light on the overall function of Sp-EVs, in the scope of infection-mediated HUS, and suggest new avenues of research for exploring the usefulness of Sp-EVs as therapeutic and diagnostic targets. IMPORTANCE Streptococcus pneumoniae-associated hemolytic uremic syndrome (Sp-HUS) is a serious and underdiagnosed deadly complication of invasive pneumococcal disease. Despite the introduction of the pneumococcal vaccine, cases of Sp-HUS continue to emerge, especially in children under the age of 2. While a lot has been studied regarding pneumococcal proteins and their role on Sp-HUS pathophysiology, little is known about the role of extracellular vesicles (EVs). In our work, we isolate and initially characterize EVs from a reference pathogenic strain (D39) and a strain isolated from a 2-year-old patient suffering from Sp-HUS. We demonstrate that despite lacking cytotoxicity toward human cells, Sp-HUS EVs are highly internalized by endothelial cells and can trigger cytokine and chemokine production in monocytes. In addition, this work specifically highlights the distinct morphological characteristics of Sp-HUS EVs and their unique cargo. Overall, this work sheds new light into potentially relevant players contained in EVs that might elucidate about pneumococcal EVs biogenesis or pose as interesting candidates for vaccine design.

Epidemiological Characterization of Isolates of Salmonella enterica and Shiga Toxin-Producing Escherichia coli from Backyard Production System Animals in the Valparaíso and Metropolitana Regions

Backyard production systems (BPS) are distributed worldwide, rearing animals recognized as reservoirs of Salmonella enterica and Shiga toxin-producing Escherichia coli (STEC), both zoonotic pathogens. The aim of this study was to characterize isolates of both pathogens obtained from animals raised in BPS from two central Chile regions. The presence of pathogens was determined by bacterial culture and confirmatory PCR for each sampled BPS, calculating positivity rates. Multivariate logistic regression was used to determine risk factors. Additionally, phenotypic antimicrobial resistance was determined. A positivity rate of 2.88% for S. enterica and 14.39% for STEC was determined for the complete study region (Valparaíso and Metropolitana regions). Risk factor analysis suggests that the presence of ruminants (OR = 1.03; 95% CI = 1.002-1.075) increases the risk of STEC-positive BPS, and the presence of ruminants (OR = 1.05; 95% CI = 1.002-1.075) and the animal handlers being exclusively women (OR = 3.54; 95% CI = 1.029-12.193) increase the risk for S. enterica/STEC positivity. Eighty percent of S. enterica isolates were multidrug resistant, and all STEC were resistant to Cephalexin. This study evidences the circulation of multidrug-resistant zoonotic bacterial strains in animals kept in BPS and the presence of factors that modify the risk of BPS positivity for both pathogens.

HUS and TTP: traversing the disease and the age spectrum

Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenia purpura (TTP) are rare diseases sharing a common pathological feature, thrombotic microangiopathy (TMA). TMA is characterized by microvascular thrombosis with consequent thrombocytopenia, microangiopathic hemolytic anemia and/or multiorgan dysfunction. In the past, the distinction between HUS and TTP was predominantly based on clinical grounds. However, clinical presentation of the two syndromes often overlaps and, the differential diagnosis is broad. Identification of underlying pathogenic mechanisms has enabled the classification of these syndromes on a molecular basis: typical HUS caused by Shiga toxin-producing Escherichia coli (STEC-HUS); atypical HUS or complement-mediated TMA (aHUS/CM-TMA) associated with genetic or acquired defects leading to dysregulation of the alternative pathway (AP) of complement; and TTP that results from a severe deficiency of the von Willebrand Factor (VWF)-cleaving protease, ADAMTS13. The etiology of TMA differs between pediatric and adult patients. Childhood TMA is chiefly caused by STEC-HUS, followed by CM-TMA and pneumococcal HUS (Sp-HUS). Rare conditions such as congenital TTP (cTTP), vitamin B12 metabolism defects, and coagulation disorders (diacylglycerol epsilon mutation) present as TMA chiefly in children under 2 years of age. In contrast secondary causes and acquired ADAMT13 deficiency are more common in adults. In adults, compared to children, diagnostic delays are more frequent due to the wide range of differential diagnoses. In this review we focus on the three major forms of TMA, STEC-HUS, aHUS and TTP, outlining the clinical presentation, diagnosis and management of the affected patients, to help highlight the salient features and the differences between adult and pediatric patients which are relevant for management.

Genome-wide association study of hemolytic uremic syndrome causing Shiga toxin-producing Escherichia coli from Sweden, 1994-2018

Shiga toxin-producing Escherichia coli (STEC) infection can cause clinical manifestations ranging from diarrhea to potentially fatal hemolytic uremic syndrome (HUS). This study is aimed at identifying STEC genetic factors associated with the development of HUS in Sweden. A total of 238 STEC genomes from STEC-infected patients with and without HUS between 1994 and 2018 in Sweden were included in this study. Serotypes, Shiga toxin gene (stx) subtypes, and virulence genes were characterized in correlation to clinical symptoms (HUS and non-HUS), and pan-genome wide association study was performed. Sixty-five strains belonged to O157:H7, and 173 belonged to non-O157 serotypes. Our study revealed that strains of O157:H7 serotype especially clade 8 were most commonly found in patients with HUS in Sweden. stx2a and stx2a + stx2c subtypes were significantly associated with HUS. Other virulence factors associated with HUS mainly included intimin (eae) and its receptor (tir), adhesion factors, toxins, and secretion system proteins. Pangenome wide-association study identified numbers of accessory genes significantly overrepresented in HUS-STEC strains, including genes encoding outer membrane proteins, transcriptional regulators, phage-related proteins, and numerous genes related to hypothetical proteins. Whole-genome phylogeny and multiple correspondence analysis of pangenomes could not differentiate HUS-STEC from non-HUS-STEC strains. In O157:H7 cluster, strains from HUS patients clustered closely; however, no significant difference in virulence genes was found in O157 strains from patients with and without HUS. These results suggest that STEC strains from different phylogenetic backgrounds may independently acquire genes determining their pathogenicity and confirm that other non-bacterial factors and/or bacteria-host interaction may affect STEC pathogenesis.

E. coli ST11 (O157:H7) does not encode a functional AcrF efflux pump

Escherichia coli is a facultative anaerobe found in a wide range of environments. Commonly described as the laboratory workhorse, E. coli is one of the best characterized bacterial species to date, however much of our understanding comes from studies involving the laboratory strain E. coli K-12. Resistance-nodulation-division efflux pumps are found in Gram-negative bacteria and can export a diverse range of substrates, including antibiotics. E. coli K-12 has six RND pumps; AcrB, AcrD, AcrF, CusA, MdtBC and MdtF, and it is frequently reported that all E. coli strains possess these six pumps. However, this is not true of E. coli ST11, a lineage of E. coli, which is primarily composed of the highly virulent important human pathogen, E. coli O157:H7. Here we show that acrF is absent from the pangenome of ST11 and that this lineage of E. coli has a highly conserved insertion within the acrF gene, which when translated encodes 13 amino acids and two stop codons. This insertion was found to be present in 97.59 % of 1787 ST11 genome assemblies. Non-function of AcrF in ST11 was confirmed in the laboratory as complementation with acrF from ST11 was unable to restore AcrF function in E. coli K-12 substr. MG1655 ΔacrB ΔacrF. This shows that the complement of RND efflux pumps present in laboratory bacterial strains may not reflect the situation in virulent strains of bacterial pathogens.

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.

Shiga Toxin (Stx) Type 1a and Stx2a Translocate through a Three-Layer Intestinal Model

Shiga toxins (Stxs) produced by ingested E. coli can induce hemolytic uremic syndrome after crossing the intact intestinal barrier, entering the bloodstream, and targeting endothelial cells in the kidney. The method(s) by which the toxins reach the bloodstream are not fully defined. Here, we used two polarized cell models to evaluate Stx translocation: (i) a single-layer primary colonic epithelial cell model and (ii) a three-cell-layer model with colonic epithelial cells, myofibroblasts, and colonic endothelial cells. We traced the movement of Stx types 1a and 2a across the barrier models by measuring the toxicity of apical and basolateral media on Vero cells. We found that Stx1a and Stx2a crossed both models in either direction. However, approximately 10-fold more Stx translocated in the three-layer model as compared to the single-layer model. Overall, the percentage of toxin that translocated was about 0.01% in the epithelial-cell-only model but up to 0.09% in the three-cell-layer model. In both models, approximately 3- to 4-fold more Stx2a translocated than Stx1a. Infection of the three-cell-layer model with Stx-producing Escherichia coli (STEC) strains showed that serotype O157:H7 STEC reduced barrier function in the model and that the damage was not dependent on the presence of the eae gene. Infection of the three-layer model with O26:H11 STEC strain TW08571 (Stx1a+ and Stx2a+), however, allowed translocation of modest amounts of Stx without reducing barrier function. Deletion of stx2a from TW08571 or the use of anti-Stx1 antibody prevented translocation of toxin. Our results suggest that single-cell models may underestimate the amount of Stx translocation and that the more biomimetic three-layer model is suited for Stx translocation inhibitor studies.

Sugar-Lectin Interactions for Direct and Selective Detection of Escherichia coli Bacteria Using QCM Biosensor

Pathogenic Escherichia coli (E. coli) remains a safety concern in the preservation and quality of green leafy vegetables. Sugar-lectin interactions provide a reliable, specific, and effective sensing platform for the detection of bacteria as compared to the tedious conventional plate counting technique. Herein, we present the synthesis of 4-(N-mannosyl) benzoic acid (4-NMBA) and 4-thiophenyl-N-mannose (4-TNM) via a two-step reductive amination for the detection of E. coli using a quartz crystal microbalance (QCM) biosensor. The 4-NMBA was synthesized with mannose and para-aminobenzoic (4-PBA), while the 4-TNM was synthesized with mannose and 4-aminophenyl disulfide (4-AHP) using water and acetic acid in a 1:1 ratio. The resultant structure of mannose derivatives (4-NMBA and 4-TNM) was characterized and confirmed using analytical tools, such as Mass Spectrometer, SEM, and FTIR. The choice of ligands (mannose derivatives) is ascribed to the specific recognition of mannose to the FimH lectin of the type 1 pilus of E. coli. Furthermore, the 4-PBA and 4-AHP conjugated to mannose increase the ligand affinity to FimH lectins. The setup of the QCM biosensor was composed of modification of the crystal surface and the covalent attachment of ligands for the detection of E. coli. The piezoelectric effect (frequency shift of the quartz) was proportional to the change in mass added to the gold crystal surface. Both the 4-NMBA- and 4-TNM-coated QCM sensors had a limit of detection of 3.7 CFU/mL and 6.6 CFU/mL with a sensitivity of 2.56 × 10³ ng/mL and 8.99 × 10^-5 ng/mL, respectively, within the dynamic range of 10³ to 10⁶ CFU/mL. This study demonstrates the application of ligand-coated QCM biosensors as a cost-effective, simple, and label-free technology for monitoring pathogenic bacteria via molecular interactions on crystal surfaces.

Diagnosis and Treatment for Shiga Toxin-Producing Escherichia coli Associated Hemolytic Uremic Syndrome

Shiga toxin-producing Escherichia coli (STEC)-associated hemolytic uremic syndrome (STEC-HUS) is a clinical syndrome involving hemolytic anemia (with fragmented red blood cells), low levels of platelets in the blood (thrombocytopenia), and acute kidney injury (AKI). It is the major infectious cause of AKI in children. In severe cases, neurological complications and even death may occur. Treating STEC-HUS is challenging, as patients often already have organ injuries when they seek medical treatment. Early diagnosis is of great significance for improving prognosis and reducing mortality and sequelae. In this review, we first briefly summarize the diagnostics for STEC-HUS, including history taking, clinical manifestations, fecal and serological detection methods for STEC, and complement activation monitoring. We also summarize preventive and therapeutic strategies for STEC-HUS, such as vaccines, volume expansion, renal replacement therapy (RRT), antibiotics, plasma exchange, antibodies and inhibitors that interfere with receptor binding, and the intracellular trafficking of the Shiga toxin.

A step forward for Shiga toxin-producing Escherichia coli identification and characterization in raw milk using long-read metagenomics

Shiga toxin-producing Escherichia coli (STEC) are a cause of severe human illness and are frequently associated with haemolytic uraemic syndrome (HUS) in children. It remains difficult to identify virulence factors for STEC that absolutely predict the potential to cause human disease. In addition to the Shiga-toxin (stx genes), many additional factors have been reported, such as intimin (eae gene), which is clearly an aggravating factor for developing HUS. Current STEC detection methods classically rely on real-time PCR (qPCR) to detect the presence of the key virulence markers (stx and eae). Although qPCR gives an insight into the presence of these virulence markers, it is not appropriate for confirming their presence in the same strain. Therefore, isolation steps are necessary to confirm STEC viability and characterize STEC genomes. While STEC isolation is laborious and time-consuming, metagenomics has the potential to accelerate the STEC characterization process in an isolation-free manner. Recently, short-read sequencing metagenomics have been applied for this purpose, but assembly quality and contiguity suffer from the high proportion of mobile genetic elements occurring in STEC strains. To circumvent this problem, we used long-read sequencing metagenomics for identifying eae-positive STEC strains using raw cow's milk as a causative matrix for STEC food-borne outbreaks. By comparing enrichment conditions, optimizing library preparation for MinION sequencing and generating an easy-to-use STEC characterization pipeline, the direct identification of an eae-positive STEC strain was successful after enrichment of artificially contaminated raw cow's milk samples at a contamination level as low as 5 c.f.u. ml-1. Our newly developed method combines optimized enrichment conditions of STEC in raw milk in combination with a complete STEC analysis pipeline from long-read sequencing metagenomics data. This study shows the potential of the innovative methodology for characterizing STEC strains from complex matrices. Further developments will nonetheless be necessary for this method to be applied in STEC surveillance.

Microbial lectome versus host glycolipidome: How pathogens exploit glycosphingolipids to invade, dupe or kill

Glycosphingolipids (GSLs) are ubiquitous components of the cell membranes, found across several kingdoms of life, from bacteria to mammals, including humans. GSLs are a subclass of major glycolipids occurring in animal lipid membranes in clusters named “lipid rafts.” The most crucial functions of GSLs include signal transduction and regulation as well as participation in cell proliferation. Despite the mainstream view that pathogens rely on protein–protein interactions to survive and thrive in their hosts, many also target the host lipids. In particular, multiple pathogens produce adhesion molecules or toxins that bind GSLs. Attachment of pathogens to cell surface receptors is the initial step in infections. Many mammalian pathogens have evolved to recognize GSL-derived receptors. Animal glycosphingolipidomes consist of multiple types of GSLs differing in terminal glycan and ceramide structures in a cell or tissue-specific manner. Interspecies differences in GSLs dictate host specificity as well as cell and tissue tropisms. Evolutionary pressure exerted by pathogens on their hosts drives changes in cell surface glycoconjugates, including GSLs, and has produced a vast number of molecules and interaction mechanisms. Despite that abundance, the role of GSLs as pathogen receptors has been largely overlooked or only cursorily discussed. In this review, we take a closer look at GSLs and their role in the recognition, cellular entry, and toxicity of multiple bacterial, viral and fungal pathogens.

Comparative Genomics of Shiga Toxin-Producing Escherichia coli Strains Isolated from Pediatric Patients with and without Hemolytic Uremic Syndrome from 2000 to 2016 in Finland

Shiga toxin-producing Escherichia coli (STEC) infection can cause mild to severe illness, such as nonbloody or bloody diarrhea, and the fatal hemolytic uremic syndrome (HUS). The molecular mechanism underlying the variable pathogenicity of STEC infection is not fully defined so far. Here, we performed a comparative genomics study on a large collection of clinical STEC strains collected from STEC-infected pediatric patients with and without HUS in Finland over a 16-year period, aiming to identify the bacterial genetic factors that can predict the risk to cause HUS and poor renal outcome. Of 240 STEC strains included in this study, 52 (21.7%) were from pediatric patients with HUS. Serotype O157:H7 was the main cause of HUS, and Shiga toxin gene subtype stx2a was significantly associated with HUS. Comparative genomics and pangenome-wide association studies identified a number of virulence and accessory genes overrepresented in HUS-associated STEC compared to non-HUS STEC strains, including genes encoding cytolethal distending toxins, type III secretion system effectors, adherence factors, etc. No virulence or accessory gene was significantly associated with risk factors for poor renal outcome among HUS patients assessed in this study, including need for and duration of dialysis, presence and duration of anuria, and leukocyte counts. Whole-genome phylogeny and multiple-correspondence analysis of pangenomes could not separate HUS STEC from non-HUS STEC strains, suggesting that STEC strains with diverse genetic backgrounds may independently acquire genetic elements that determine their varied pathogenicity. Our findings indicate that nonbacterial factors, i.e., characteristics of the host immunity, might affect STEC virulence and clinical outcomes.

IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) is a serious public health burden worldwide which causes outbreaks of gastrointestinal diseases and the fatal hemolytic uremic syndrome (HUS) characterized by the triad of mechanical hemolytic anemia, thrombocytopenia, and acute renal failure. Understanding the mechanism underlying the disease severity and patient outcome is of high importance. Using comparative genomics on a large collection of clinical STEC strains from STEC-infected patients with and without HUS, our study provides a reference of STEC genetic factors/variants that can be used as predictors of the development of HUS, which will aid risk assessment at the early stage of STEC infection. Additionally, our findings suggest that nonbacterial factors may play a primary role in the renal outcome in STEC-infected patients with HUS; further studies are needed to validate this.

Isolation, identification, and antibiogram studies of Escherichia coli from ready-to-eat foods in Mymensingh, Bangladesh

Background and Aim

Ready-to-eat (RTE) foods are widely used at home, restaurants, and during festivals in Bangladesh. So it is very important to investigate possible microbial contamination in RTE foods. Therefore, this study aimed to determine the total coliform count (TCC), isolate, identify, and characterize the Escherichia coli in RTE foods. The antimicrobial sensitivity of E. coli obtained from RTE foods was also performed using 12 commonly used antibiotics.

Materials and Methods

A total of 100 RTE food samples were collected aseptically and comprised of ten samples each: Burger, pizza, sandwich, chicken roll, chicken meat loaf, chicken fry, salad vegetable, ice-cream, yogurt, and milkshake sold in Mymensingh City. Samples were inoculated onto Eosin methylene blue agar and incubated at 37°C for 24 h. Isolation and identification of bacteria were performed based on cultural, staining, and biochemical properties, followed by a polymerase chain reaction.

Results

The TCC in Chicken meat loaf, burger, pizza, sandwich, salad vegetable ice-cream, and yogurt samples were 3.57 ± 0.96, 3.69 ± 0.08, 3.50 ± 0.60, 2.60 ± 0.20, 4.09 ± 0.29, 4.44 ± 0.25, and 3.14 ± 0.30 mean log colony-forming units ± standard deviation/mL, respectively. The study found a higher prevalence of E. coli in RTE salad vegetable products than in RTE meat and milk products. Forty percent of the mixed vegetable salad samples showed positive results for E. coli. Whereas E. coli prevalence in RTE meat and milk products was 20% and 16.7%, respectively. All the 21 isolates were subjected to antibiotic susceptibility test against 12 different antibiotics. It was observed that 46.1% were susceptible, 16.6% were intermediate, 46.1% were resistant, and 47.6% were multidrug-resistant (MDR) among seven different antibiotic classes. E. coli isolates were resistant to cephalexin, ceftazidime, oxytetracycline, and ampicillin and sensitive to gentamycin, followed by kanamycin, ceftriaxone, colistin, and enrofloxacin.

Conclusion

The study revealed that RTE foods are a serious issue from a public health point of view. To achieve a safer level of E. coli in RTE foods sold for human consumption, public food outlets must improve hygienic and good production procedures. Moreover, MDR E. coli in these foods pose serious public health threats.

Prevalence of Shiga toxin-producing Escherichia coli in Yezo sika deer (Cervus nippon yesoensis) in the Tokachi sub-prefecture of Hokkaido, Japan

In food hygiene, the surveillance of foodborne pathogens in wild animals is indispensable because we cannot control hygienic status of them. Yezo sika deer (Cervus nippon yesoensis), which are found only on the island of Hokkaido, Japan, are the most common game animal in the country. In this study, we analyzed the incidence of Shiga toxin-producing Escherichia coli (STEC) in Yezo sika deer hunted in the Tokachi sub-prefecture, which is one of the densest zones for the sub-species. Real-time polymerase chain reaction testing detected STEC in 18.3% of fecal samples (59/323) collected from deer hunted between 2016 and 2017, whereas no Shigella and Salmonella markers were detected. No correlation was found between STEC detection from fecal samples and characteristics of carcasses, such as hunting area, age, and fascioliasis. From 59 STEC-positive fecal samples, we isolated 37 STEC strains, including 34 O- and H-genotyped strains, in which 16 different serogroups were detected. Genetic analysis revealed that our isolates included various stx gene types (stx1⁺/stx2^-, stx1⁺/stx2⁺, and stx1^-/stx2⁺) and carried eae. This study demonstrated that STEC strains with various features colonized the Yezo sika deer, similar to other subspecies of sika deer. We conclude that continuous surveillance activity is important to monitor the suitability of game animals as a food source and to assess the validity of the food safety management system for game meat production.

Gene expression profile and injury sites in mice treated with Shiga toxin 2 and lipopolysaccharide as a Shiga toxin-associated hemolytic uremic syndrome model

Shiga toxin 2 (Stx2) and lipopolysaccharide (LPS) contribute to the development of hemolytic uremic syndrome (HUS). Mouse models of HUS induced by LPS/Stx2 have been used for elucidating HUS pathophysiology and for therapeutic development. However, the underlying molecular mechanisms and detailed injury sites in this model remain unknown. We analyzed mouse kidneys after LPS/Stx2 administration using microarrays. Decreased urinary osmolality and urinary potassium were observed after LPS/Stx2 administration, suggestive of distal nephron disorders. A total of 1212 and 1016 differentially expressed genes were identified in microarrays at 6 and 72 h after LPS/Stx2 administration, respectively, compared with those in controls. Ingenuity pathway analysis revealed activation of TNFR1/2, iNOS, and IL-6 signaling at both time points, and inhibition of pathways associated with lipid metabolism at 72 h only. The strongly downregulated genes in the 72-h group were expressed in the distal nephrons. In particular, genes associated with distal convoluted tubule (DCT) 2 /connecting tubule (CNT) and principal cells of the cortical collection duct (CCD) were downregulated to a greater extent than those associated with DCT1 and intercalated cells. Stx receptor globotriaosylceramide 3 (Gb3) revealed no colocalization with DCT1-specific Pvalb and intercalated cell-specific Slc26a4 but did present colocalization with Slc12a3 (present in both DCT1 and DCT2), and Aqp2 in principal cells. Gb3 localization tended to coincide with the segment in which the downregulated genes were present. Thus, the LPS/Stx2-induced kidney injury model represents damage to DCT2/CNT and principal cells in the CCD, based on molecular, biological, and physiological findings.

Genotyping Based on CRISPR Loci Diversity and Pathogenic Potential of Diarrheagenic Escherichia coli

Diarrheagenic Escherichia coli (DEC) can cause epidemic diarrhea worldwide. The pathogenic potential of different strains is diverse and the continuous emergence of pathogenic strains has brought serious harm to public health. Accurately distinguishing and identifying DEC with different virulence is necessary for epidemiological surveillance and investigation. Clustered regularly interspaced short palindromic repeats (CRISPR) typing is a new molecular method that can distinguish pathogenic bacteria excellently and has shown great promise in DEC typing. The purpose of this study was to investigate the discrimination of CRISPR typing method for DEC and explore the pathogenicity potential of DEC based on CRISPR types (CT). The whole genome sequences of 789 DEC strains downloaded from the database were applied CRISPR typing and serotyping. The D value (Simpson’s index) with 0.9709 determined that CRISPR typing had a higher discrimination. Moreover, the same H antigen strains with different O seemed to share more identical spacers. Further analyzing the strains CRISPR types and the number of virulence genes, it was found that there was a significant correlation between the CRISPR types and the number of virulence genes (p < 0.01). The strains with the largest number of virulence genes concentrated in CT25 and CT56 and the number of virulence genes in CT264 was the least, indicating that the pathway potential of different CRISPR types was variable. Combined with the Caco-2 cell assay of the laboratory strains, the invasion capacity of STEC strains of different CRISPR types was different and there was no significant difference in the invasion rate between different CRISPR type strains (p > 0.05). In the future, with the increase of the number of strains that can be studied experimentally, the relationship between CRISPR types and adhesion and invasion capacities will be further clarified.

Nanobody-Based Bispecific Neutralizer for Shiga Toxin-Producing E. coli

Currently, no specific therapeutics are available for foodborne Shiga toxin-producing Escherichia coli (STEC) infections that cause severe gastroenteritis and life-threatening complications of hemolytic uremic syndrome (HUS). As STEC attachment to intestinal epithelium might increase the host absorption of Shiga toxins and severity of the disease, we were inspired to develop a bispecific neutralizer capable of blocking its Shiga toxin and adhesin intimin simultaneously. Two nanobodies against the B subunit of Shiga toxin 2 (Stx2B) and the C terminus of Intimin (IntC280) were genetically fused together as the bispecific neutralizer, and it can be efficiently produced in a conventional E. coli expression system. We demonstrated that each of the nanobody modules in the bispecific format showed increased antigen binding capability and was able to functionally neutralize the binding of Stx2B or IntC280 to the respective host receptors even in the presence of the two virulence factors together. Moreover, the bispecific neutralizer was relatively stable to harsh storage conditions and gastrointestinal pH extremes. Taking into account its easy and economical production and superior pharmaceutical properties, we believe that a nanobody-based bispecific neutralizer would be more favorable and practical to be developed as a therapeutic to fight STEC in the developing world.

Therapeutic Antibodies Against Shiga Toxins: Trends and Perspectives

Shiga toxins (Stx) are AB₅-type toxins, composed of five B subunits which bind to Gb₃ host cell receptors and an active A subunit, whose action on the ribosome leads to protein synthesis suppression. The two Stx types (Stx1 and Stx2) and their subtypes can be produced by Shiga toxin-producing Escherichia coli strains and some Shigella spp. These bacteria colonize the colon and induce diarrhea that may progress to hemorrhagic colitis and in the most severe cases, to hemolytic uremic syndrome, which could lead to death. Since the use of antibiotics in these infections is a topic of great controversy, the treatment remains supportive and there are no specific therapies to ameliorate the course. Therefore, there is an open window for Stx neutralization employing antibodies, which are versatile molecules. Indeed, polyclonal, monoclonal, and recombinant antibodies have been raised and tested in vitro and in vivo assays, showing differences in their neutralizing ability against deleterious effects of Stx. These molecules are in different phases of development for which we decide to present herein an updated report of these antibody molecules, their source, advantages, and disadvantages of the promising ones, as well as the challenges faced until reaching their applicability.

Prevalence of genotypic antimicrobial resistance in clinical Shiga toxin-producing Escherichia coli in Norway, 2018 to 2020

Introduction

Shiga toxin-producing Escherichia coli (STEC) can cause severe to fatal disease in humans. Antimicrobial treatment is sometimes necessary, but contraindicated due to undesirable clinical outcome. However, recent studies have shown promising outcomes following antimicrobial treatment. Before the establishment of a possible antimicrobial treatment strategy for STEC infections, the prevalence of antimicrobial resistance in STEC needs to be determined.

Gap statement

The resistance status of Norwegian clinical STEC is not known and should be assessed.

Aim

We aim to characterize genotypic antimicrobial resistance determinants in clinical STEC in Norway, and determine the prevalence of genotypic resistance in order to inform possible antimicrobial treatment options for STEC infections.

Methodology

We included all clinical STEC submitted to the Norwegian Reference Laboratory from March 2018 to April 2020. All samples were whole-genome sequenced and screened for genotypic antimicrobial resistance,virulence determinants and plasmid incompatibility groups. We performed phylogenetic clustering of STEC by core-genome multi-locus sequence typing, and statistical association analyses between isolate characteristics and genotypic resistance.

Results

A total of 459 STEC were analysed. For 385 (83.9 %) STEC we did not identify any antimicrobial resistance determinants. Seventy-four STEC (16.1 %) harboured antimicrobial resistance determinants against one or more antimicrobial classes. The most frequent genotypic resistance was identified against aminoglycosides (10.5 %). Thirty-nine STEC (8.5 %) had a multi-drug resistance (MDR) genotype. Genotypic resistance was more prevalent in non-O157 than O157 STEC (P=0.02). A positive association was seen between genotypic resistance and the low-virulent STEC O117:H7 phylogenetic cluster (no. 14) (P<0.001). Genotypic resistance was not significantly associated to high-virulent STEC. STEC O146:H28 and isolates harbouring the plasmid replicon type IncQ1 were positively associated with MDR.

Conclusion

The overall prevalence of genotypic resistance in clinical STEC in Norway is low (16.1 %). Genotypic resistance is more prevalent in non-O157 strains compared to O157 strains, and not significantly associated to high-virulent STEC. Resistance to antimicrobials suggested for treatment, especially azithromycin is low and may present an empiric treatment alternative for severe STEC infections.

Genomic Characteristics of Stx2e-Producing Escherichia coli Strains Derived from Humans, Animals, and Meats

Shiga toxin (Stx) can be classified into two types, Stx1 and Stx2, and different subtypes. Stx2e is a subtype commonly causing porcine edema disease and rarely reported in humans. The purpose of this study was to analyze the prevalence and genetic characteristics of Stx2e-producing Escherichia coli (Stx2e-STEC) strains from humans compared to strains from animals and meats in China. Stx2e-STEC strains were screened from our STEC collection, and whole-genome sequencing was performed to characterize their genetic features. Our study showed a wide distribution of Stx2e-STEC among diverse hosts and a higher proportion of Stx2e-STEC among human STEC strains in China. Three human Stx2e-STEC isolates belonged to O100:H30, Onovel26:H30, and O8:H9 serotypes and varied in genetic features. Human Stx2e-STECs phylogenetically clustered with animal- and food-derived strains. Stx2e-STEC strains from animals and meat showed multidrug resistance, while human strains were only resistant to azithromycin and tetracycline. Of note, a high proportion (55.9%) of Stx2e-STEC strains, including one human strain, carried the heat-stable and heat-labile enterotoxin-encoding genes st and lt, exhibiting a STEC/enterotoxigenic E. coli (ETEC) hybrid pathotype. Given that no distinct genetic feature was found in Stx2e-STEC strains from different sources, animal- and food-derived strains may pose the risk of causing human disease.

A case of hemolytic uremic syndrome caused by Shiga toxin-producing Escherichia coli after pericardiectomy

The majority of cases of Shiga toxin-producing Escherichia coli are self-limited; however, the infection can occasionally be complicated by more severe phenomena, such as thrombotic microangiopathy, with resultant end-organ damage to the kidneys, colon, nervous system, and various other tissues. Shiga toxin-induced hemolytic uremic syndrome (ST-HUS)-the constellation of thrombocytopenia, hemolysis, and renal failure resulting from thrombotic microangiopathy in a subset of infections producing the Shiga toxin-is classically observed in the pediatric population. Nevertheless, the diagnosis should be considered in adults with this presentation, and especially in those with colonic findings suggestive of ischemia. ST-HUS must also be distinguished from other thrombotic microangiopathies and related conditions, such as disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and complement-mediated HUS, as these diagnoses prompt alternate management strategies. Here, we present a case of ST-HUS in a gentleman following pericardiectomy who was infected with non-O157:H7 E. coli producing Shiga toxin 2.

Shiga Toxins as Antitumor Tools

Shiga toxins (Stxs), also known as Shiga-like toxins (SLT) or verotoxins (VT), constitute a family of structurally and functionally related cytotoxic proteins produced by the enteric pathogens Shigella dysenteriae type 1 and Stx-producing Escherichia coli (STEC). Infection with these bacteria causes bloody diarrhea and other pathological manifestations that can lead to HUS (hemolytic and uremic syndrome). At the cellular level, Stxs bind to the cellular receptor Gb3 and inhibit protein synthesis by removing an adenine from the 28S rRNA. This triggers multiple cellular signaling pathways, including the ribotoxic stress response (RSR), unfolded protein response (UPR), autophagy and apoptosis. Stxs cause several pathologies of major public health concern, but their specific targeting of host cells and efficient delivery to the cytosol could potentially be exploited for biomedical purposes. Moreover, high levels of expression have been reported for the Stxs receptor, Gb3/CD77, in Burkitt's lymphoma (BL) cells and on various types of solid tumors. These properties have led to many attempts to develop Stxs as tools for biomedical applications, such as cancer treatment or imaging, and several engineered Stxs are currently being tested. We provide here an overview of these studies.

Two Paralogous Gb3/CD77 Synthases in Birds Show Different Preferences for Their Glycoprotein and Glycosphingolipid Substrates

Most glycosyltransferases show remarkable gross and fine substrate specificity, which is reflected in the old one enzyme-one linkage paradigm. While human Gb3/CD77 synthase is a glycosyltransferase that synthesizes the Galα1→4Gal moiety mainly on glycosphingolipids, its pigeon homolog prefers glycoproteins as acceptors. In this study, we characterized two Gb3/CD77 synthase paralogs found in pigeons (Columba livia). We evaluated their specificities in transfected human teratocarcinoma 2102Ep cells by flow cytofluorometry, Western blotting, high-performance thin-layer chromatography, mass spectrometry and metabolic labelling with 14C-galactose. We found that the previously described pigeon Gb3/CD77 synthase (called P) can use predominately glycoproteins as acceptors, while its paralog (called M), which we serendipitously discovered while conducting this study, efficiently synthesizes Galα1→4Gal caps on both glycoproteins and glycosphingolipids. These two paralogs may underlie the difference in expression profiles of Galα1→4Gal-terminated glycoconjugates between neoavians and mammals.

Diversity of Non-O157 Shiga Toxin-Producing Escherichia coli Isolated from Cattle from Central and Southern Chile

Simple Summary

Cattle are the main reservoir of Shiga toxin-producing E. coli (STEC), foodborne pathogens that cause severe disease and outbreaks. However, not all STEC cause human illnesses or have the same virulence potential. Characterizing strains isolated worldwide allows insights into how strains spread and which isolates have a more significant risk potential. This study described STEC isolation rates from cattle in Chile and characterized 30 isolates. We obtained 93 STEC isolates from 56/446 (12.6%) fecal cattle samples. Then, 30 non-O157 STEC isolates were selected for complete characterization; we found isolates of 16 different sequence types and 17 serotypes. One isolate was resistant to tetracycline and carried resistance genes against the drug. Surveyed virulence genes (n = 31) were present from 13% to 100% of isolates, and one isolate carried 26/31 virulence genes. Most isolates (90%; 27/30) carried the stx2 gene, which is frequently linked to strains causing severe disease. A phylogenetic reconstruction demonstrated that isolates clustered based on serotypes, independent of their geographical origin (Central or Southern Chile). These results indicate that cattle in Chile carry a wide diversity of STEC potentially pathogenic for humans based on the presence of virulence genes.

Abstract

Cattle are the main reservoir of Shiga toxin-producing Escherichia coli (STEC), one of the world’s most important foodborne pathogens. The pathogen causes severe human diseases and outbreaks. This study aimed to identify and characterize non-O157 STEC isolated from cattle feces from central and southern Chile. We analyzed 446 cattle fecal samples and isolated non-O157 STEC from 12.6% (56/446); a total of 93 different isolates were recovered. Most isolates displayed β-glucuronidase activity (96.8%; 90/93) and fermented sorbitol (86.0%; 80/93), whereas only 39.8% (37/93) were resistant to tellurite. A subgroup of 30 representative non-O157 STEC isolates was selected for whole-genome sequencing and bioinformatics analysis. In silico analysis showed that they grouped into 16 different sequence types and 17 serotypes; the serotypes most frequently identified were O116:H21 and O168:H8 (13% each). A single isolate of serotype O26:H11 was recovered. One isolate was resistant to tetracycline and carried resistance genes tet(A) and tet(R); no other isolate displayed antimicrobial resistance or carried antimicrobial resistance genes. The intimin gene (eae) was identified in 13.3% (4/30) of the genomes and 90% (27/30) carried the stx2 gene. A phylogenetic reconstruction demonstrated that the isolates clustered based on serotypes, independent of geographical origin. These results indicate that cattle in Chile carry a wide diversity of STEC potentially pathogenic for humans based on the presence of critical virulence genes.

Primary Human Renal Proximal Tubular Epithelial Cells (pHRPTEpiCs): Shiga Toxin (Stx) Glycosphingolipid Receptors, Stx Susceptibility, and Interaction with Membrane Microdomains

Tubular epithelial cells of the human kidney are considered as targets of Shiga toxins (Stxs) in the Stx-mediated pathogenesis of hemolytic–uremic syndrome (HUS) caused by Stx-releasing enterohemorrhagic Escherichia coli (EHEC). Analysis of Stx-binding glycosphingolipids (GSLs) of primary human renal proximal tubular epithelial cells (pHRPTEpiCs) yielded globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) with Cer (d18:1, C16:0), Cer (d18:1, C22:0), and Cer (d18:1, C24:1/C24:0) as the dominant lipoforms. Investigation of detergent-resistant membranes (DRMs) and nonDRMs, serving as equivalents for the liquid-ordered and liquid-disordered membrane phase, respectively, revealed the prevalence of Gb3Cer and Gb4Cer together with cholesterol and sphingomyelin in DRMs, suggesting lipid raft association. Stx1a and Stx2a exerted strong cellular damage with half-maximal cytotoxic doses (CD₅₀) of 1.31 × 10² pg/mL and 1.66 × 10³ pg/mL, respectively, indicating one order of magnitude higher cellular cytotoxicity of Stx1a. Surface acoustic wave (SAW) real-time interaction analysis using biosensor surfaces coated with DRM or nonDRM fractions gave stronger binding capability of Stx1a versus Stx2a that correlated with the lower cytotoxicity of Stx2a. Our study underlines the substantial role of proximal tubular epithelial cells of the human kidney being associated with the development of Stx-mediated HUS at least for Stx1a, while the impact of Stx2a remains somewhat ambiguous.

Quality Improvements in Management of Children with Acute Diarrhea Using a Multiplex-PCR-Based Gastrointestinal Pathogen Panel

Conventional methods for etiologic diagnoses of acute gastroenteritis (AGE) are time consuming and have low positive yield leading to limited clinical value. This study aimed to investigate quality improvements in patient management, antibiotic stewardship, and in-hospital infection transmission prevention using BioFire^® FilmArray^® Gastrointestinal Panel (GI Panel) in children with acute diarrhea. This was a prospective study recruiting children < 19 years old with new onset diarrhea during the study period, and a matched historical cohort study of children diagnosed with AGE during the 4 years prior. Patients in the prospective cohort underwent stool testing with GI Panel and conventional methods. A total of 182 patients were included in the prospective cohort, of which 85.7% (n = 156) had community-onset and 14.3% (n = 26) had hospital-onset diarrhea. A higher pathogen positivity rate for community-onset diarrhea was observed by the GI Panel (58.3%, n = 91) compared to conventional studies (42.3%, n = 66) (p = 0.005) and historical cohort (31.4%, n = 49) (p < 0.001). The stool tests reporting time after admission was 25 (interquartile range, IQR 17-46) hours for the GI Panel, and 72 (IQR 48-96) hours for the historical cohort (p < 0.001). A significant reduction in antibiotic use was observed in the prospective cohort compared to historical cohort, 35.3% vs. 71.8%; p < 0.001), respectively. Compared to the GI Panel, norovirus ICT was only able to detect 4/11 (36.4%) patients with hospital-onset and 14/27 (51.8%) patients with community-onset diarrhea. The high positivity rate and rapid reporting time of the GI Panel had clinical benefits for children admitted for acute diarrhea, especially by reducing antibiotic use and enabling early adequate infection precaution and isolation.

Hemolytic uremic syndrome following complicated appendicitis in a child: what is the missing link?

We herein describe an 18-month-old boy who underwent initially successful surgical and antibiotic treatment of complicated appendicitis with postoperative occurrence of hemolytic uremic syndrome (HUS). This complication was due to Shiga toxin-producing Escherichia coli (STEC) found secondarily in rectal swabs but not in the peritoneal cavity. The literature indicates that a causal link may exist between these two entities, and HUS could be considered an iatrogenic complication of appendicitis management due to a multimodal stress effect in non-symptomatic STEC carriers.

Area-Level Clustering of Shiga Toxin-Producing Escherichia coli Infections and Their Socioeconomic and Demographic Factors in Ontario, Canada: An Ecological Study

Shiga toxin-producing Escherichia coli (STEC) infections are an important health burden for human populations in Ontario and worldwide. We assessed 452 STEC cases that were reported to Ontario's reportable disease surveillance system between 2015 and 2017. A retrospective scan statistic using a Poisson model was used to detect high-rate STEC clusters at the forward sortation area (FSA; the first three digits of a postal code) level. A significant spatial cluster in the southwest region of Ontario was identified. A case-case logistic regression analysis was applied to compare FSA-level socioeconomic and demographic characteristics among STEC cases included inside the spatial cluster with cases outside of the cluster. Cases included in the spatial cluster had higher odds of living in FSAs with a low median family income, low proportion of lone-parent families, and low proportion of the visible minority population. In addition, STEC cases inside the cluster had higher odds of coming from rural FSAs. Our study demonstrated that STEC cases were spatially clustered in Ontario and their clustering was associated with FSA-level socioeconomic and demographic determinants of cases.

Missing the sweet spot: one of the two N-glycans on human Gb3/CD77 synthase is expendable

N-glycosylation is a ubiquitous posttranslational modification that may influence folding, subcellular localization, secretion, solubility and oligomerization of proteins. In this study, we examined the effects of N-glycans on the activity of human Gb3/CD77 synthase, which catalyzes the synthesis of glycosphingolipids with terminal Galα1 → 4Gal (Gb3 and the P1 antigen) and Galα1 → 4GalNAc disaccharides (the NOR antigen). The human Gb3/CD77 synthase contains two occupied N-glycosylation sites at positions N121 and N203. Intriguingly, we found that while the N-glycan at N203 is essential for activity and correct subcellular localization, the N-glycan at N121 is dispensable and its absence did not reduce, but, surprisingly, even increased the activity of the enzyme. The fully N-glycosylated human Gb3/CD77 synthase and its glycoform missing the N121 glycan correctly localized in the Golgi, whereas a glycoform without the N203 site partially mislocalized in the endoplasmic reticulum. A double mutein missing both N-glycans was inactive and accumulated in the endoplasmic reticulum. Our results suggest that the decreased specific activity of human Gb3/CD77 synthase glycovariants results from their improper subcellular localization and, to a smaller degree, a decrease in enzyme solubility. Taken together, our findings show that the two N-glycans of human Gb3/CD77 synthase have opposing effects on its properties, revealing a dual nature of N-glycosylation and potentially a novel regulatory mechanism controlling the biological activity of proteins.

Shiga Toxin-Associated Hemolytic Uremic Syndrome: Specificities of Adult Patients and Implications for Critical Care Management

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.

Differential Outcome between BALB/c and C57BL/6 Mice after Escherichia coli O157:H7 Infection Is Associated with a Dissimilar Tolerance Mechanism

Enterohemorrhagic Escherichia coli (EHEC) infections can result in a wide range of clinical presentations despite that EHEC strains belong to the O157:H7 serotype, one of the most pathogenic forms. Although pathogen virulence influences disease outcome, we emphasize the concept of host-pathogen interactions, which involve resistance or tolerance mechanisms in the host that determine total host fitness and bacterial virulence. Taking advantage of the genetic differences between mouse strains, we analyzed the clinical progression in C57BL/6 and BALB/c weaned mice infected with an E. coli O157:H7 strain. We carefully analyzed colonization with several bacterial doses, clinical parameters, intestinal histology, and the integrity of the intestinal barrier, as well as local and systemic levels of antibodies to pathogenic factors. We demonstrated that although both strains had comparable susceptibility to Shiga toxin (Stx) and the intestinal bacterial burden was similar, C57BL/6 showed increased intestinal damage, alteration of the integrity of the intestinal barrier, and impaired renal function that resulted in increased mortality. The increased survival rate in the BALB/c strain was associated with an early specific antibody response as part of a tolerance mechanism.

Glomerulonephritis in AKI: From Pathogenesis to Therapeutic Intervention

Acute kidney injury (AKI) is increasingly emerging as a global emergency. Sepsis, major surgery, and nephrotoxic drugs are the main causes of AKI in hospitalized patients. However, glomerulonephritis accounts for about 10% of AKI episodes in adults, mainly related to rapidly progressive glomerulonephritis resulting from granulomatous polyangiitis (GPA, Wegener granulomatosis), microscopic polyangiitis (MPA), and anti-glomerular basement membrane (GBM) disease. Also, diffuse proliferative lupus nephritis, immunoglobulin A nephropathy, post-streptococcal glomerulonephritis, mixed cryoglobulinemia, mesangiocapillary glomerulonephritis, membranous nephropathy, hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and scleroderma can induce acute renal failure. Early diagnosis of AKI due to glomerulonephritis is crucial for prompt, effective management to improve short- and long-term outcomes. Kidney biopsy is the gold standard for the diagnosis of glomerular disease, but it is not frequently performed in critically ill patients because of their clinical conditions. In this setting, a growing number of diagnostic assays can support the working hypothesis, including antineutrophil cytoplasmic antibodies (ANCAs), anti-double-stranded DNA antibodies, anti-GBM antibodies, antistreptolysin O and anti-DNase B antibodies, cryoglobulins, antiphospholipid antibodies, and complement levels. Therapeutic strategies in AKI patients with glomerulonephritis include high-dose corticosteroids, cyclophosphamide, and plasma exchange. This article reviews the wide spectrum of glomerulopathies associated with AKI, describing the immunological mechanisms underlying glomerular diseases and presenting an overview of the therapeutic options.

Genomic Insights Into Clinical Shiga Toxin-Producing Escherichia coli Strains: A 15-Year Period Survey in Jönköping, Sweden

Shiga toxin-producing Escherichia coli (STEC) are important foodborne pathogens that can cause human infections ranging from asymptomatic carriage to bloody diarrhea (BD) and fatal hemolytic uremic syndrome (HUS). However, the molecular mechanism of STEC pathogenesis is not entirely known. Here, we demonstrated a large scale of molecular epidemiology and in-depth genomic study of clinical STEC isolates utilizing clinical and epidemiological data collected in Region Jönköping County, Sweden, over a 15-year period. Out of 184 STEC isolates recovered from distinct patients, 55 were from patients with BD, and 129 were from individuals with non-bloody stools (NBS). Five individuals developed HUS. Adults were more associated with BD. Serotypes O157:H7, O26:H11, O103:H2, O121:H19, and O104:H4 were more often associated with BD. The presence of Shiga toxin-encoding gene subtypes stx 2a, stx 2a + stx 2c, and stx 1a + stx 2c was associated with BD, while stx 1 a was associated with milder disease. Multiplex virulence and accessory genes were correlated with BD; these genes encode toxins, adhesion, autotransporters, invasion, and secretion system. A number of antimicrobial resistance (AMR) genes, such as aminoglycoside, aminocoumarin, macrolide, and fluoroquinolone resistance genes, were prevalent among clinical STEC isolates. Whole-genome phylogeny revealed that O157 and non-O157 STEC isolates evolved from distinct lineages with a few exceptions. Isolates from BD showed more tendency to cluster closely. In conclusion, this study unravels molecular trait of clinical STEC strains and identifies genetic factors associated with severe clinical outcomes, which could contribute to management of STEC infections and disease progression if confirmed by further functional validation.

Human Gb3/CD77 synthase produces P1 glycotope-capped N-glycans, which mediate Shiga toxin 1 but not Shiga toxin 2 cell entry

The human Gb3/CD77 synthase, encoded by the A4GALT gene, is an unusually promiscuous glycosyltransferase. It synthesizes the Galα1→4Gal linkage on two different glycosphingolipids (GSLs), producing globotriaosylceramide (Gb3, CD77, Pk) and the P1 antigen. Gb3 is the major receptor for Shiga toxins (Stxs) produced by enterohemorrhagic Escherichia coli. A single amino acid substitution (p.Q211E) ramps up the enzyme's promiscuity, rendering it able to attach Gal both to another Gal residue and to GalNAc, giving rise to NOR1 and NOR2 GSLs. Human Gb3/CD77 synthase was long believed to transfer Gal only to GSL acceptors, therefore its GSL products were, by default, considered the only human Stx receptors. Here, using soluble, recombinant human Gb3/CD77 synthase and p.Q211E mutein, we demonstrate that both enzymes can synthesize the P1 glycotope (terminal Galα1→4Galβ1→4GlcNAc-R) on a complex type N-glycan and a synthetic N-glycoprotein (saposin D). Moreover, by transfection of CHO-Lec2 cells with vectors encoding human Gb3/CD77 synthase and its p.Q211E mutein, we demonstrate that both enzymes produce P1 glycotopes on N-glycoproteins, with the mutein exhibiting elevated activity. These P1-terminated N-glycoproteins are recognized by Stx1 but not Stx2 B subunits. Finally, cytotoxicity assays show that Stx1 can use P1 N-glycoproteins produced in CHO-Lec2 cells as functional receptors. We conclude that Stx1 can recognize and use P1 N-glycoproteins in addition to its canonical GSL receptors to enter and kill the cells, while Stx2 can use GSLs only. Collectively, these results may have important implications for our understanding of the Shiga toxin pathology.

Effects of antimicrobials on Shiga toxin production in high-virulent Shiga toxin-producing Escherichia coli

PURPOSE

Antimicrobial treatment of Shiga toxin-producing Escherichia coli (STEC) infections is controversial because antimicrobials may stimulate Shiga toxin (Stx) production, and thereby increase the risk of developing haemolytic uremic syndrome (HUS). Previous in vitro studies have shown this mainly in infections caused by STEC serotype O157:H7. The aim of this study was to investigate induction of Stx transcription and production in different serotypes of STEC isolated from severely ill patients, following their exposure in vitro to six different classes of antimicrobials.

METHODS

We investigated Stx transcription and production in 12 high-virulent STEC strains, all carrying the stx2a gene, of six different serotypes following their exposure to six classes of antimicrobials. Liquid cultures of the STEC strains were incubated with sub-inhibitory concentrations of the antimicrobials. We used reverse-transcription quantitative PCR to measure the relative expression of Stx2a mRNA and an enzyme-linked immunosorbent assay to quantify Stx production.

RESULTS

In general the antibiotics tested showed only minor effects on transcriptional levels of Stx2a. Ciprofloxacin caused an increase of Stx production in all but two strains, while gentamicin, meropenem and azithromycin did not induce Stx production in any of the STEC strains examined. STEC O104:H4 was the serotype that in greatest extent responded to antimicrobial exposure with an increase of stx2a transcription and Stx production.

CONCLUSION

Gentamicin, meropenem and azithromycin exposure did not result in elevated Stx production. We recommend that this finding is investigated further in the search for candidates for future antimicrobial treatment of STEC.

Association of Ct Values from Real-Time PCR with Culture in Microbiological Clearance Samples for Shiga Toxin-Producing Escherichia coli (STEC)

Shiga toxin-producing Escherichia coli (STEC) are associated with acute gastroenteritis worldwide, which induces a high economic burden on both healthcare and individuals. Culture-independent diagnostic tests (CIDT) in frontline microbiology laboratories have been implemented in Alberta since 2019. The objectives of this study were to determine the association between gene detection and culture positivity over time using STEC microbiological clearance samples and also to establish the frequency of specimen submission. Both stx genes’ amplification by real-time PCR was performed with DNA extracted from stool samples using the easyMAG system. Stools were inoculated onto chromogenic agar for culture. An association between gene detection and culture positivity was found to be independent of which stx gene was present. CIDT can provide rapid reporting with less hands-on time and technical expertise. However, culture is still important for surveillance and early cluster detection. In addition, stool submissions could be reduced from daily to every 3–5 days until a sample is negative by culture.

Prevalence and antibiotic resistance profile of Shiga toxin-producing Escherichia coli isolated from diarrheal samples

BACKGROUND AND OBJECTIVES

Enterohemorrhagic Escherichia coli (EHEC) causes bloody and non-bloody diarrhea, intestinal infection and extraintestinal complications in humans. This study aimed to isolate and evaluate the prevalence of E. coli O157: H7 and other Shiga toxin-producing E. coli (STEC) and identify the virulence genes (stx1, stx2, hly and eaeA) from patients with diarrhea. Also, the antibiotic resistance profile of the isolated strains was evaluated.

MATERIALS AND METHODS

A total of 100 stool samples were collected from patients with acute diarrhea referring to the hospital and clinics in Isfahan County, Iran. Phenotypic tests and PCR assay were used for detection of E. coli O157: H7 and other Shiga toxin-producing E. coli. The presence of virulence genes (stx1, stx2, hly and eaeA) were identified by PCR. The antibiotic resistance profile of the isolates was determined using the agar disk diffusion method. The results were analyzed descriptively by Sigma stat version 4 software.

RESULTS

Seventy - eight out of 100 samples (78%) were contaminated with E. coli. E. coli O157 was isolated from five samples (6.4%), of which only two strains (2.56%) were identified as E. coli O157: H7. According to the results, out of two E. coli O157: H7 isolates, one (50%) isolate contained eaeA and two isolates (100%) contained Stx1, Stx2, hlyA genes. Out of three (3.84%) E. coli O157: HN, one of the isolate (33.3%) contained stx1 and, two isolates (66.7%) were positive for hlyA genes. Also, the results revealed that six strains (7.69%) were non-O157: H7 STEC, of which two isolates (33.3%) contained stx1 and four isolates (66.7%) were positive for stx2 and hlyA genes. The results of antibiogram tests revealed that all of the STEC isolates (100%) were sensitive to imipenem followed by kanamycin, gentamicin and nitrofurantoin (91%). High resistance (54.5%) to ampicillin and ciprofloxacin was observed among the STEC isolates.

CONCLUSION

The results of the current study showed that although the prevalence of E. coli O157: H7 was low among patients with diarrhea, the other STEC strains with relative resistance to antibiotics are more prevalent.

Epidemiology of Shiga Toxin-Producing Escherichia coli Infections in Southern Italy after Implementation of Symptom-Based Surveillance of Bloody Diarrhea in the Pediatric Population

Shiga toxin-producing Escherichia coli (STEC) infections result in a significant public health impact because of the severity of the disease that, in young children especially, can lead to hemolytic-uremic syndrome (HUS). A rise in the number of HUS cases was observed in the Apulia region of Italy from 2013 to 2017, and so, in 2018, a symptom-based surveillance system for children with bloody diarrhea (BD) was initiated in order to detect and manage STEC infections. The objective of the study was to describe the epidemiology of STEC infections in children from June 2018 to August 2019. Children <15 years old with BD were hospitalized and tested for STEC. Real-time PCR for virulence genes (stx1, stx2, eae) and serogroup identification tests were performed on stool samples/rectal swabs of cases. STEC infection was detected in 87 (10.6%) BD cases. The median age of STEC cases was 2.7 years, and 60 (68.9%) were <4. Of these 87 cases, 12 (13.8%) came from households with diarrhea. The reporting rate was 14.2/100,000, with the highest incidence in cases from the province of Bari (24.2/100,000). Serogroups O26 and O111 were both detected in 22/87 (25.3%) cases. Co-infections occurred in 12.6% of cases (11/87). Twenty-nine STEC were positive for stx1, stx2, and eae. Five cases (5.7%) caused by O26 (n = 2), O111 (n = 2), and O45 (n = 1) developed into HUS. A risk-oriented approach based on the testing of children with BD during the summer may represent a potentially beneficial option to improve the sensitivity of STEC surveillance, not only in Italy but also in the context of Europe as a whole.

Phenotypic and Genotypic Antimicrobial Resistance in Non-O157 Shiga Toxin-Producing Escherichia coli Isolated From Cattle and Swine in Chile

Non-O157 Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that causes bloody diarrhea and hemolytic-uremic syndrome in humans, and a major cause of foodborne disease. Despite antibiotic treatment of STEC infections in humans is not recommended, the presence of antimicrobial-resistant bacteria in animals and food constitutes a risk to public health, as the pool of genes from which pathogenic bacteria can acquire antibiotic resistance has increased. Additionally, in Chile there is no information on the antimicrobial resistance of this pathogen in livestock. Thus, the aim of this study was to characterize the phenotypic and genotypic antimicrobial resistance of STEC strains isolated from cattle and swine in the Metropolitan region, Chile, to contribute relevant data to antimicrobial resistance surveillance programs at national and international level. We assessed the minimal inhibitory concentration of 18 antimicrobials, and the distribution of 12 antimicrobial resistance genes and class 1 and 2 integrons in 54 STEC strains. All strains were phenotypically resistant to at least one antimicrobial drug, with a 100% of resistance to cefalexin, followed by colistin (81.5%), chloramphenicol (14.8%), ampicillin and enrofloxacin (5.6% each), doxycycline (3.7%), and cefovecin (1.9%). Most detected antibiotic resistance genes were dfrA1 and tetA (100%), followed by tetB (94.4%), bla_TEM−1 (90.7%), aac(6)-Ib (88.9%), bla_AmpC (81.5%), cat1 (61.1%), and aac(3)-IIa (11.1%). Integrons were detected only in strains of swine origin. Therefore, this study provides further evidence that non-O157 STEC strains present in livestock in the Metropolitan region of Chile exhibit phenotypic and genotypic resistance against antimicrobials that are critical for human and veterinary medicine, representing a major threat for public health. Additionally, these strains could have a competitive advantage in the presence of antimicrobial selective pressure, leading to an increase in food contamination. This study highlights the need for coordinated local and global actions regarding the use of antimicrobials in animal food production.

Hemolytic uremic syndrome caused by Shiga toxin-producing Escherichia coli in children: incidence, risk factors, and clinical outcome

BACKGROUND

Hemolytic uremic syndrome (HUS) is a multisystemic disease. In a nationwide study, we characterized the incidence, clinical course, and prognosis of HUS caused by Shiga toxin (Stx)-producing Escherichia coli (STEC) strains with emphasis on risk factors, disease severity, and long-term outcome.

METHODS

The data on pediatric HUS patients from 2000 to 2016 were collected from the medical records. STEC isolates from fecal cultures of HUS and non-HUS patients were collected from the same time period and characterized by whole genome sequencing analysis.

RESULTS

Fifty-eight out of 262 culture-positive cases developed verified (n = 58, 22%) STEC-HUS. Another 29 cases had probable STEC-HUS, the annual incidence of STEC-HUS being 0.5 per 100,000 children. Eleven different serogroups were detected, O157 being the most common (n = 37, 66%). Age under 3 years (OR 2.4), stx2 (OR 9.7), and stx2a (OR 16.6) were found to be risk factors for HUS. Fifty-five patients (63%) needed dialysis. Twenty-nine patients (33%) developed major neurological symptoms. Complete renal recovery was observed in 57 patients after a median 4.0 years of follow-up. Age under 3 years, leukocyte count over 20 × 10⁹/L, and need for dialysis were predictive factors for poor renal outcome.

CONCLUSIONS

Age under 3 years, stx2, and stx2a were risk factors for HUS in STEC-positive children. However, serogroup or stx types did not predict the renal outcome or major CNS symptoms.