Interventions for preventing diarrhoea-associated haemolytic uraemic syndrome.

BACKGROUND: Haemolytic uraemic syndrome (HUS) is a common cause of acquired kidney failure in children and rarely in adults. The most important risk factor for development of HUS is a gastrointestinal infection by Shiga toxin-producing Escherichia coli (STEC). This review addressed the interventions aimed at secondary prevention of HUS in patients with diarrhoea who were infected with a bacteria that increase the risk of HUS. OBJECTIVES: Our objective was to evaluate evidence regarding secondary preventative strategies for HUS associated with STEC infections. In doing so, we sought to assess the effectiveness and safety of interventions as well as their potential to impact the morbidity and death associated with this condition. SEARCH METHODS: We searched the Cochrane Kidney and Transplant Register of Studies up to 12 November 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. SELECTION CRITERIA: Studies were considered based on the methods, participants, and research goals. Only randomised controlled trials were considered eligible for inclusion. The participants of the studies were paediatric and adult patients with diarrhoeal illnesses due to STEC. The primary outcome of interest was incidence of HUS. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures as recommended by Cochrane. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. MAIN RESULTS: We identified four studies (536 participants) for inclusion that investigated four different interventions including antibiotics (trimethoprim-sulfamethoxazole), anti-Shiga toxin antibody-containing bovine colostrum, Shiga toxin binding agent (Synsorb Pk: a silicon dioxide-based agent), and a monoclonal antibody against Shiga toxin (urtoxazumab). The overall risk of bias was unclear for selection, performance and detection bias and low for attrition, reporting and other sources of bias. It was uncertain if trimethoprim-sulfamethoxazole reduced the incidence of HUS compared to no treatment (47 participants: RR 0.57, 95% CI 0.11-2.81, very low certainty evidence). Adverse events relative to this review, need for acute dialysis, neurological complication and death were not reported. There were no incidences of HUS in either the bovine colostrum group or the placebo group. It was uncertain if bovine colostrum caused more adverse events (27 participants: RR 0.92, 95% CI 0.42 to 2.03; very low certainty evidence). The need for acute dialysis, neurological complications or death were not reported. It is uncertain whether Synsorb Pk reduces the incidence of HUS compared to placebo (353 participants: RR 0.93, 95% CI 0.39 to 2.22; very low certainty evidence). Adverse events relevant to this review, need for acute dialysis, neurological complications or death were not reported. One study compared two doses of urtoxazumab (3.0 mg/kg and 1.0 mg/kg) to placebo. It is uncertain if either 3.0 mg/kg urtoxazumab (71 participants: RR 0.34, 95% CI 0.01 to 8.14) or 1.0 mg/kg urtoxazumab (74 participants: RR 0.95, 95% CI 0.79 to 1.13) reduced the incidence of HUS compared to placebo (very low certainty evidence). Low certainty evidence showed there may be little or no difference in the number of treatment-emergent adverse events with either 3.0 mg/kg urtoxazumab (71 participants: RR 1.00, 95% CI 0.84 to 1.18) or 1.0 mg/kg urtoxazumab (74 participants: RR 0.95, 95% CI 0.79 to 1.13) compared to placebo. There were 25 serious adverse events reported in 18 patients: 10 in the placebo group, and 9 and 6 serious adverse events in the 1.0 mg/kg and 3.0 mg/kg urtoxazumab groups, respectively. It is unclear how many patients experienced these adverse events in each group, and how many patients experienced more than one event. It is uncertain if either dose of urtoxazumab increased the risk of neurological complications or death (very low certainty evidence). Need for acute dialysis was not reported. AUTHORS' CONCLUSIONS: The included studies assessed antibiotics, bovine milk, and Shiga toxin inhibitor (Synsorb Pk) and monoclonal antibodies (Urtoxazumab) against Shiga toxin for secondary prevention of HUS in patients with diarrhoea due to STEC. However, no firm conclusions about the efficacy of these interventions can be drawn given the small number of included studies and the small sample sizes of those included studies. Additional studies, including larger multicentre studies, are needed to assess the efficacy of interventions to prevent development of HUS in patients with diarrhoea due to STEC infection.

EspA-loaded mesoporous silica nanoparticles can efficiently protect animal model against enterohaemorrhagic E. coli O157: H7.

In the present study, the application of mesoporous silica nanoparticles (MSNPs) loaded with recombinant EspA protein, an immunogen of enterohaemorrhagic E. coli, was investigated in the case of BALB/c mice immunization against the bacterium. MSNPs of 96.9 ± 15.9 nm in diameter were synthesized using template removing method. The immunization of mice was carried out orally and subcutaneously. Significant immune responses to the antigen were observed for the immunized mice when rEspA-loaded MSNPs were administered in both routes in comparison to that of the antigen formulated using a well-known adjuvant, i.e. Freund's. According to the titretitre of serum IL-4, the most potent humoral responses were observed when the mice were immunized subcutaneously with antigen-loaded MSNPs (244, 36 and 14 ng/dL of IL-4 in the serum of mice immunized subcutaneously or orally by antigen-loaded MSNPs, and subcutaneously by Freund's adjuvant formulated-antigen, respectively). However, the difference in serum IgG and serum IgA was not significant in mice subcutaneously immunized with antigen-loaded MSNPs and mice immunized with Freund's adjuvant formulated-antigen. Finally, the immunized mice were challenged orally by enterohaemorrhagic E. coli cells. The amount of bacterial shedding was significantly reduced in faecesfaeces of the animals immunized by antigen-loaded MSNPs in both subcutaneous and oral routes.

Ciprofloxacin reduces the risk of hemolytic uremic syndrome in patients with Escherichia coli O104:H4-associated diarrhea.

BACKGROUND: Whether antibiotic treatment in patients with enterohemorrhagic Escherichia coli (EHEC)-associated diarrhea influences the risk of hemolytic uremic syndrome (HUS) has still to be elucidated. PATIENTS AND METHODS: During the EHEC epidemic which occurred in northern Germany in spring 2011, 24 patients with E. coli O104:H4 infection were treated at our hospitals, 19 of whom developed HUS. The use of antibiotics before and after the onset of HUS was documented, and the outcome in patients with and without antibiotic treatment was evaluated. RESULTS: Of the 24 patients with EHEC-associated diarrhea, seven received antibiotics before any signs of HUS were present (ciprofloxacin, cefotaxime, amoxicillin and/or metronidazole). Four of these seven patients (57 %) and 15 of the 17 patients (88 %) who were treated without antibiotics developed HUS (p = 0.12). Microbiological testing showed all E. coli O104:H4 to be extended-spectrum beta lactamase producers and thus susceptible only to fluoroquinolones, aminoglycosides and carbapenems. Two of the five patients (40 %) treated with ciprofloxacin and 17 of the 19 patients (89 %) treated without ciprofloxacin developed HUS (p = 0.043). CONCLUSION: In our E. coli O104:H4-infected patients, treatment of diarrhea with antibiotics did not increase the risk of HUS. Significantly fewer patients treated with ciprofloxacin developed HUS than patients who did not receive ciprofloxacin.

Aqueous extracts of yerba mate (Ilex paraguariensis) as a natural antimicrobial against Escherichia coli O157:H7 in a microbiological medium and pH 6.0 apple juice.

Ilex paraguariensis is popularly used in the preparation of a tea infusion (yerba mate), most commonly produced and consumed in the South American countries of Uruguay, Paraguay, Argentina, and Brazil. In this study, aqueous extracts of commercial tea, derived from the holly plant species I. paraguariensis were evaluated for their ability to inhibit or inactivate Escherichia coli O157:H7 in a microbiological medium and modified apple juice. Dialyzed, lyophilized aqueous extracts were screened for antimicrobial activity against E. coli O157:H7 strains ATCC 43894 and 'Cider' in tryptic soy broth (TSB) and apple juice (adjusted to pH 6.0 to allow for growth of the bacterium). A mixture of the two strains was used as the inoculum when apple juice was used as the medium. MBCs were determined to be ca. 5 and 10 mg/ml for ATCC 43894 and 'Cider', respectively, in TSB. Higher concentrations of the extract were required to inactivate E. coli O157:H7 in pH-adjusted apple juice. An approximate 4.5-log reduction was observed for E. coli O157:H7 treated with 40 mg/ml extract. It was concluded that aqueous extracts from commercial yerba mate have potential to be used as antimicrobials in foods and beverages against pathogenic E. coli O157:H7.

Pathogenesis and treatment of Shiga toxin-producing Escherichia coli infections.

PURPOSE OF REVIEW: Shiga toxin-producing Escherichia coli cause hemorrhagic colitis and hemolytic uremic syndrome. We will summarize the literature on incidence and outcomes of these infections, and then review the pathogenesis to explain the current recommendations against antibiotic use and to suggest alternative therapies. RECENT FINDINGS: Shiga toxin-producing E. coli continue to be prevalent in the industrialized world because of dissemination in food products contaminated by ruminant feces. Declines in ground beef-related outbreaks have been matched by increased cases related to green vegetables. Fifteen percent of patients infected with E. coli O157:H7 progress to hemolytic uremic syndrome, but this figure may reach 50% if antibiotics are used. Mechanisms for bacteriophage induction causing Shiga toxin production, and for Shiga toxin dissemination to endothelium in gut, kidney and brain, may explain the negative effects of antibiotics and lead to rational therapies. Shiga toxin binders were not effective in clinical trials, but more avid binding agents may be. Current treatment recommendations are to maintain hydration to prevent thrombotic complications. Human vaccines are unlikely to be utilized. Cattle vaccines may prove the most significant approach to this disease. SUMMARY: Improved understanding of Shiga toxin-producing Escherichia coli pathophysiology and progression to hemolytic uremic syndrome provides the basis for prevention, prophylactic and treatment strategies.

Neutralizing activity of bovine colostral antibody against verotoxin derived from enterohemorrhagic Escherichia coli O157:H7 in mice.

The neutralization efficacy of bovine colostral antibody against verotoxin (VT) 1 and 2 was investigated. Cows were immunized with VT1 or VT2 fourteen times at 7-day intervals. A colostral antibody exhibiting high titers was obtained from immunized cows. Survival rates were evaluated in mice administered VT1 or VT2, and those infected with Escherichia coli (E. coli) O157:H7 producing VT1 or VT2. Survival rates after VT1 administration were 100% in the single-administration group, 90% in the repeat-administration group, and 78.6% in the control group. Survival rates after VT2 were 75.0% in the single-administration group, and 100% in the repeat-administration group. All mice in the control group died. Colostral antibody and fosfomycin (FOM) in the colostral antibody group and FOM and skim milk in the control group were administered three times per day for 5 days to mice infected with E. coli O157:H7 producing VT1 or VT2. Survival rates after inoculation with E. coli O157:H7 producing VT1 were 80.0% in the colostral antibody group, and 63.6% in the control group. Survival rates after inoculation with E. coli O157:H7 producing VT2 were 83.3% in the colostral antibody group, and 20.0% in the control group. The survival rate in mice without treatment following inoculation with E. coli O157:H7 producing VT2 was 88.2%. The survival rates in mice infected with E. coli O157:H7 strains producing VT1 or VT2 improved after administration of this colostral antibody, which exhibited neutralization efficacy against VT.

Contribution of polyunsaturated fatty acids to Shiga toxin cytotoxicity in human renal tubular epithelium-derived cells.

Shiga toxin (Stx) produced by enterohemorrhagic Escherichia coli is a critical factor in the onset of hemolytic uremic syndrome. The current study was designed to assess whether n-3 and (or) n-6 polyunsaturated fatty acids (PUFA) act as a valuable adjunct to prevent the cell injury of renal tubule cells in the emergence of HUS. The target cells, ACHN cells derived from human tubule epithelium, were cultured with each PUFA, then exposed to Stx-1 or Stx-2. The rank order of potency of PUFA to inhibit the cell death caused by each toxin was as follows: EPA > AA = DHA >> LNA. There were dose-response relations in the efficacy of each PUFA. No prophylactic effect was found in the cultures with LA. Immunofluorescence assays revealed that both the expression of the toxin receptor on ACHN cells and binding between the toxin and cells were unaffected by the PUFA. These results suggest that EPA is the most efficacious PUFA against the renal tubule cell injury caused by Stx, which may be assigned to an alteration in the intracellular pathway leading to cell death.

A plant-based oral vaccine to protect against systemic intoxication by Shiga toxin type 2.

Hemolytic uremic syndrome, the leading cause of kidney failure in children, often follows infection with enterohemorrhagic Escherichia coli and is mediated by the Shiga type toxins, particularly type 2 (Stx2), produced by such strains. The challenge in protecting against this life-threatening syndrome is to stimulate an immune response at the site of infection while also protecting against Shiga intoxication at distal sites such as the kidney. As one approach to meeting this challenge, we sought to develop and characterize a prototypic orally delivered, plant-based vaccine against Stx2, an AB5 toxin. First, we genetically inactivated the Stx2 active A subunit gene and then optimized both subunit genes for expression in plants. The toxoid genes were then transformed into the Nicotiana tabacum (tobacco) cell line NT-1 by Agrobacterium tumefaciens-mediated transformation. Toxoid expression was detected in NT-1 cell extracts, and the assembly of the holotoxoid was confirmed. Finally, mice were immunized by feeding with the toxoid-expressing NT-1 cells or by parenteral immunization followed by oral vaccination (prime-boost strategy). The immunized mice produced Stx2-specific mucosal IgA and Stx2-neutralizing serum IgG. The protective efficacy of these responses was assessed by challenging the immunized mice with E. coli O91:H21 strain B2F1, an isolate that produces an activatable variant of Stx2 (Stx2d) and is lethal to mice. The oral immunization fully protected mice from the challenge. Results of this study demonstrated that a plant-based oral vaccine can confer protection against lethal systemic intoxication.