Shiga-Toxin E. coli Hemolytic Uremic Syndrome: Review of Management and Long-term Outcome

Model-informed repurposing of eliglustat for treatment and prophylaxis of Shiga toxin-producing Escherichia coli hemolytic-uremic syndrome (STEC-HUS) in children

BACKGROUND

Shiga toxin-producing Escherichia coli hemolytic-uremic syndrome (STEC-HUS) is a severe illness predominantly affecting young children, with limited treatment options beyond supportive care. Eliglustat, approved for Gaucher disease, shows potential in reducing Shiga toxin binding to target glomerular endothelial cells in vitro, prompting interest as a treatment for STEC-HUS. However, it remains unknown what dose is likely to be effective and safe for treatment of STEC-HUS in the pediatric population. We hypothesize that effective and safe levels of eliglustat can be reached in children.

METHODS

We identified pharmacokinetic targets of efficacy for treatment and prophylaxis of STEC-HUS based on a preclinical model and human cardiac safety data. Then, we developed oral and intravenous dosing regimens using population pharmacokinetic (popPK) simulations based on an existing model enriched to allow extrapolation to a simulated virtual pediatric population. These dosing regimens were then confirmed using a verified physiologically based pharmacokinetic (PBPK) model.

RESULTS

We simulated, using popPK data, oral and intravenous dosing regimens resulting in adequate target exposure in > 90% of all patients, with minimal expected risk for cardiotoxicity. Confirmation of these dosing regimens with PBPK modeling resulted in very similar exposure, with lower interindividual variability and minimal toxicity potential.

CONCLUSIONS

Based on pharmacokinetic modeling, we developed oral and intravenous eliglustat dosing regimens that are likely safe and effective for treatment of STEC-HUS and prophylaxis in case of outbreaks of STEC infections. Clinical evaluation of these dosing regimens in children suspected of or diagnosed with STEC-HUS is required and should include assessment of pharmacokinetics, efficacy, and safety (e.g., ECG monitoring).

Evaluation of Single and Multi-Strain Probiotics with Gentamicin Against E. coli O157:H7: Insights from In Vitro and In Vivo Studies

The emergence of antibiotic-resistant food-borne pathogens, especially Escherichia coli O157:H7, highlights the urgent need for innovative treatment strategies, particularly in light of rising resistances and the ongoing controversy surrounding antibiotic use in response to E. coli O157:H7 infections. To address this issue, we explored the potential of single- and multi-strain probiotics, both independently and in combination with gentamicin, through a series of in vitro and in vivo experiments. In vitro, gentamicin alone produced a mean inhibition zone of 12.9 ± 2.27 mm against E. coli O157:H7. The combination of gentamicin with single-strain probiotics (P1) increased the inhibition zone to 16.5 ± 2.24 mm (p < 0.05), while the combination with multi-strain probiotics (P2) resulted in the largest inhibition zone of 19 ± 2.8 mm (p < 0.05). In vivo, mice infected with E. coli O157:H7 and treated with P2, gentamicin (G), or their combination (G+P2), achieved 100% survival, no pathological symptoms, and full weight recovery within seven days. Conversely, mice treated with P1 or G+P1 exhibited lower survival rates (71.4% and 85%, respectively) and slower weight recovery. Hematological parameters improved across all groups, but kidney function analysis showed significantly higher serum creatinine levels in the P1, G, G+P1, and G+P2 groups compared to the P2 group (P1: 0.63 ± 0.15 mg/dL; G: 0.34 ± 0.09 mg/dL; G+P1: 0.53 ± 0.19 mg/dL; G+P2: 0.5 ± 0.23 mg/dL vs. P2: 0.24 ± 0.2 mg/dL). Histological analysis showed better intestinal and kidney tissue recovery in the P2 group, while the P1 and G+P1 groups exhibited abnormal ileal structures and severe cortical bleeding. These findings highlight the promise of multi-strain probiotics, alone or in conjunction with antibiotics, as a therapeutic strategy for E. coli O157:H7 infections. However, the nephrotoxicity associated with gentamicin co-administration remains a limitation, warranting further studies to optimize this approach.

[Thrombopenia and hemolytic anemia in acute and emergency medicine : Detailed view at thrombotic microangiopathies]

Recognizing anemia and thrombpenia in acute and emergency medicine is easy. Acute (microangiopathic hemolytic) anemia and thrombopenia can be a sign of thrombotic microangiopathy (TMA). TMA syndromes are potentially life-threatening diseases. Diagnosing a TMA syndrome, causal differentiation and treatment require specialist knowledge that is not always available in acute and emergency medicine. Many differential diagnoses and examinations are usually necessary to make a correct diagnosis. Therefore, a standardized diagnostic algorithm is helpful for early diagnosis and treatment initiation.

Epidemiological Characteristics of Shiga Toxin-Producing Escherichia coli Responsible for Infections in the Polish Pediatric Population

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens causing hemorrhagic colitis and hemolytic uremic syndrome (HUS) in children and the elderly. Stool samples were collected from 180 children hospitalized in five pediatric centers in Poland in 2018-2022. Direct stx1/stx2 gene detection by PCR in feces and E. coli isolates was performed. Antibiotic susceptibility was tested according to EUCAST v.12. Randomly selected isolates were serotyped with O157 antiserum and genotyped by pulsed-field gel electrophoresis (PFGE). A total of 44 E. coli isolates were confirmed as STEC by PCR. Among them, 84.4% were positive for stx2, and equally 6,8% for only stx1 and both stx1 and stx2 genes. The stx1 gene was also found in one Citrobacter freundii isolate. E. coli serotype O157 was present in 97.6% of the isolates. STEC infections most often occurred between June-October with a peak in July and August (51%). The highest, 77.8% of STEC isolates were found in the 1-5 years old group. No extended-spectrum β-lactamases (ESBL) were found. Resistance only to amoxicillin/clavulanic acid (24.4%), piperacillin/tazobactam (3%), cefotaxime (6%), gentamicin (6%), ciprofloxacin (3%), azithromycin (3%), trimethoprim/sulfamethoxazole (24,2%) was detected. PFGE analysis showed 18 PFGE types with no clonal distribution. Eight isolates with A, B, and C PFGE types showed genetic relatedness in the type with no detection of transmission way of distribution. STEC strains pose a serious threat to human health, therefore demographic and epidemiological characteristics are crucial for their surveillance.

Eculizumab in severe Shiga toxin-mediated haemolytic uraemic syndrome

Shiga toxin (Stx)-producing Escherichia coli-mediated haemolytic uraemic syndrome is a primary thrombotic microangiopathy, typified by the development of microangiopathic haemolytic anaemia, thrombocytopaenia and acute renal failure. It is a leading cause of acute renal failure in paediatrics, with a second peak in prevalence in adults over the age of 60. Presentations of Stx-producing E. coli-mediated haemolytic uraemic syndrome in young adults are rare. We present the case of a previously well female in her early 30s presenting with Stx-producing E. coli-mediated haemolytic uraemic syndrome with severe renal and neurological manifestations. Eculizumab was administered due to the severity of presentation and disease trajectory refractory to initial supportive therapy. A significant clinical and biochemical improvement was observed following eculizumab.

A novel Shiga toxin 2a neutralizing antibody therapeutic with low immunogenicity and high efficacy

Shiga toxin-producing Escherichia coli infections are difficult to treat due to the risk of antibiotic-induced stress upregulating the production of toxins, medical treatment is consequently limited to supportive care to prevent the development of hemolytic uremic syndrome (HUS). Here, we introduce a potentially therapeutic humanized mouse monoclonal antibody (Hu-mAb 2-5) targeting Stx2a, the most common Shiga toxin subtype identified from outbreaks. We demonstrate that Hu-mAb 2-5 has low immunogenicity in healthy adults ex vivo and high neutralizing efficacy in vivo, protecting mice from mortality and HUS-related tissue damage.

Surveillance of Shiga toxin-producing Escherichia coli associated bloody diarrhea in Argentina

In Argentina, hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC-HUS) infection is endemic, and reliable data about prevalence and risk factors have been available since 2000. However, information about STEC-associated bloody diarrhea (BD) is limited. A prospective study was performed during the period October 2018-June 2019 in seven tertiary-hospitals and 18 referral units from different regions, aiming to determine (i) the frequency of STEC-positive BD cases in 714 children aged 1-9 years of age and (ii) the rate of progression of bloody diarrhea to HUS. The number and regional distribution of STEC-HUS cases in the same hospitals and during the same period were also assessed. Twenty-nine (4.1%) of the BD patients were STEC-positive, as determined by the Shiga Toxin Quik Chek (STQC) test and/or the multiplex polymerase chain reaction (mPCR) assay. The highest frequencies were found in the Southern region (Neuquén, 8.7%; Bahía Blanca, 7.9%), in children between 12 and 23 month of age (8.8%), during summertime. Four (13.8%) cases progressed to HUS, three to nine days after diarrhea onset. Twenty-seven STEC-HUS in children under 5 years of age (77.8%) were enrolled, 51.9% were female; 44% were Stx-positive by STQC and all by mPCR. The most common serotypes were O157:H7 and O145:H28 and the prevalent genotypes, both among BD and HUS cases, were stx2a-only or -associated. Considering the endemic behavior of HUS and its high incidence, these data show that the rate of STEC-positive cases is low among BD patients. However, the early recognition of STEC-positive cases is important for patient monitoring and initiation of supportive treatment.

Monitoring the genetic variation of some Escherichia coli strains in wild birds and cattle

To date, there is limited data about the genetic relationship of Escherichia coli between wild birds and cattle because these birds act as silent vectors for many zoonotic bacteria. This study aimed to elucidate the role of rooming wild birds in the vicinity of cattle farm in transmission of the same pathogenic E. coli variants, identifying their virulence, resistance traits and genetic similarities of fimH virulence gene. About 240 faecal/cloacal swabs were collected from both species and examined bacteriologically. Escherichia coli was yielded in 45.8% and 32.5%, respectively, of examined cattle and wild birds. The most prevalent detected E. coli serovar was O26. High tetracycline and chloramphenicol resistance were recorded; however, gentamycin and ciprofloxacin exhibited the highest sensitivity rates. Polymerase chain reaction (PCR) conserved genotypic resistance (tetA and blaCTX-M) and virulence attributes (fimH, stx1, eaeA and ompA) of E. coli isolates were discussed in detail. The fimH gene revealed 100% sequence similarity when comparing with different E. coli isolates globally and locally. Finally, a close genetic association of E. coli with both wild birds and cattle was detected, thus strengthening its role in the dissemination of the infection via environment. Prevention and conservative policy should be carried as E. coli constitute enormous significant zoonotic risks to livestock and animal workers. Also, further studies to the whole genome sequencing of fimH, other virulence and resistance genes of E. coli are recommended trying to limit the possibilities of co-infection and transfer among different species.Contribution: The current study recorded updated data about the critical infectious role of wild birds to livestock, including cattle farms in Egypt. It also delivered some recommendations for good hygienic practices in cattle farms which must be implemented for handling animal manure.

Bruton's tyrosine kinase inhibition attenuates disease progression by reducing renal immune cell invasion in mice with hemolytic-uremic syndrome

Hemolytic-uremic syndrome (HUS) can occur as a complication of an infection with Shiga-toxin (Stx)-producing Escherichia coli. Patients typically present with acute kidney injury, microangiopathic hemolytic anemia and thrombocytopenia. There is evidence that Stx-induced renal damage propagates a pro-inflammatory response. To date, therapy is limited to organ-supportive strategies. Bruton's tyrosine kinase (BTK) plays a pivotal role in recruitment and function of immune cells and its inhibition was recently shown to improve renal function in experimental sepsis and lupus nephritis. We hypothesized that attenuating the evoked immune response by BTK-inhibitors (BTKi) ameliorates outcome in HUS. We investigated the effect of daily oral administration of the BTKi ibrutinib (30 mg/kg) and acalabrutinib (3 mg/kg) in mice with Stx-induced HUS at day 7. After BTKi administration, we observed attenuated disease progression in mice with HUS. These findings were associated with less BTK and downstream phospholipase-C-gamma-2 activation in the spleen and, subsequently, a reduced renal invasion of BTK-positive cells including neutrophils. Only ibrutinib treatment diminished renal invasion of macrophages, improved acute kidney injury and dysfunction (plasma levels of NGAL and urea) and reduced hemolysis (plasma levels of bilirubin and LDH activity). In conclusion, we report here for the first time that BTK inhibition attenuates the course of disease in murine HUS. We suggest that the observed reduction of renal immune cell invasion contributes - at least in part - to this effect. Further translational studies are needed to evaluate BTK as a potential target for HUS therapy to overcome currently limited treatment options.

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.

Shiga Toxin 2 Triggers C3a-Dependent Glomerular and Tubular Injury through Mitochondrial Dysfunction in Hemolytic Uremic Syndrome

Shiga toxin (Stx)-producing Escherichia coli is the predominant offending agent of post-diarrheal hemolytic uremic syndrome (HUS), a rare disorder of microvascular thrombosis and acute kidney injury possibly leading to long-term renal sequelae. We previously showed that C3a has a critical role in the development of glomerular damage in experimental HUS. Based on the evidence that activation of C3a/C3a receptor (C3aR) signaling induces mitochondrial dysregulation and cell injury, here we investigated whether C3a caused podocyte and tubular injury through induction of mitochondrial dysfunction in a mouse model of HUS. Mice coinjected with Stx2/LPS exhibited glomerular podocyte and tubular C3 deposits and C3aR overexpression associated with cell damage, which were limited by C3aR antagonist treatment. C3a promoted renal injury by affecting mitochondrial wellness as demonstrated by data showing that C3aR blockade reduced mitochondrial ultrastructural abnormalities and preserved mitochondrial mass and energy production. In cultured podocytes and tubular cells, C3a caused altered mitochondrial fragmentation and distribution, and reduced anti-oxidant SOD2 activity. Stx2 potentiated the responsiveness of renal cells to the detrimental effects of C3a through increased C3aR protein expression. These results indicate that C3aR may represent a novel target in Stx-associated HUS for the preservation of renal cell integrity through the maintenance of mitochondrial function.

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: An Update on Host Factors and Biomedical Applications

Shiga toxins (Stxs) are classic bacterial toxins and major virulence factors of toxigenic Shigella dysenteriae and enterohemorrhagic Escherichia coli (EHEC). These toxins recognize a glycosphingolipid globotriaosylceramide (Gb3/CD77) as their receptor and inhibit protein synthesis in cells by cleaving 28S ribosomal RNA. They are the major cause of life-threatening complications such as hemolytic uremic syndrome (HUS), associated with severe cases of EHEC infection, which is the leading cause of acute kidney injury in children. The threat of Stxs is exacerbated by the lack of toxin inhibitors and effective treatment for HUS. Here, we briefly summarize the Stx structure, subtypes, in vitro and in vivo models, Gb3 expression and HUS, and then introduce recent studies using CRISPR-Cas9-mediated genome-wide screens to identify the host cell factors required for Stx action. We also summarize the latest progress in utilizing and engineering Stx components for biomedical applications.

Pathogenic potential of Escherichia coli O157 and O26 isolated from young Belgian dairy calves by recto-anal mucosal swab culturing

AIMS

The purpose of this study was to investigate the occurrence of Escherichia coli O157 and O26 on Belgian dairy cattle farms, the presence of virulence genes in the confirmed isolates and the association of E. coli O26 presence with calf diarrhoea.

METHODS AND RESULTS

In total, 233 recto-anal mucosal swabs (RAMS) were obtained from healthy and diarrheic dairy calves on three farms, each alternately visited three consecutive times. RAMS were analysed for presence of E. coli O157 and O26, and stx1, stx2 and eae virulence genes. Overall, 19% of RAMS tested positive for E. coli O157, while 31% tested positive for E. coli O26. The majority of isolates possessed both stx and eae, denoting a high pathogenic potential to humans. While both serogroups persisted at farm level, persistence within the same animal over time appeared to be relatively rare. Interestingly, E. coli O26 was already abundantly present at a younger age compared to E. coli O157. Calf diarrhoea could not be associated with presence of E. coli O26.

CONCLUSIONS

Young dairy calves are important on-farm reservoirs of potentially pathogenic E. coli O157 and O26. A role of E. coli O26 in calf diarrhoea could not be confirmed.

SIGNIFICANCE AND IMPACT OF THE STUDY

O157 and O26 are responsible for the majority of human STEC infections. Gaining more epidemiological information regarding their occurrence and persistence on cattle farms will contribute to a better understanding of STEC ecology and risk of human transmission.

Interaction of Bovine Lymphocytes with Products of Shiga Toxin-Producing Escherichia coli

Shiga toxin-producing Escherichia coli (STEC) produce a number of virulence factors that interfere with lymphocyte functions, including mitogen- and antigen-activated proliferation and pro-inflammatory cytokine synthesis. Here we describe how to isolate lymphocyte subsets from bovine peripheral blood as well as methods that we have used to study the effects of STEC products on lymphocyte proliferation and cytokine production. We also describe an assay that allows for the detection of association of a given protein with lymphocytes.

Isolation and characterization of Escherichia coli serotype O157:H7 and other verotoxin-producing E. coli in healthy Indian cattle

Background and Aim:

Cattle are the main reservoir of Escherichia coli O157:H7 and other verotoxigenic E. coli (VTEC); therefore, there is an increased risk of infection to humans by either direct or indirect mode of transmissions. However, the prevalence of E. coli O157:H7 in the healthy cattle population of India is yet to be ascertained. This study aimed to screen the dairy cattle in and around Pune, Maharashtra, India, for verotoxin-producing E. coli O157:H7.

Materials and Methods:

A total of 257 rectal swabs were collected from 15 different organized and unorganized dairy farms of Pune during the period, January-March 2015. The screening involved enrichment in EC broth followed by differential identification on MacConkey sorbitol agar. The presumptive positive isolates were further confirmed by multiplex polymerase chain reaction (PCR) using primers specific to rfbE (O157), fliC (H7), VT1 (MK1), and VT2 (MK2). Vero-toxicity and antibiotic sensitivity were examined in PCR confirmed isolates.

Results:

Out of the 257 samples analyzed, 1.9% (2/105) were positive for O157:H7 and 39% (41/105) were positive for VTEC. Two PCR confirmed positive O157:H7 strains and two randomly selected PCR-positive VT strains exhibited in vitro cytopathic effect on Vero cells on day-7 post-inoculation. Antibiotic sensitivity profiling of O157:H7 strains exhibited resistance against penicillin G, kanamycin, ampicillin, tetracycline, gentamycin, cefotaxime, streptomycin, and piperacillin.

Conclusion:

These findings reveal the presence of pathogenic E. coli O157:H7 in the healthy cattle of Pune; in a situation, wherein regular surveillance for O157:H7 is not a norm. Therefore, the findings presented herein warrant routine surveillance and public awareness to prevent the transfer of such pathogens and manage health risks to the public.

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.