Risk Of Hemolytic Uremic Syndrome Research Articles

The Diversity of Escherichia coli Pathotypes and Vaccination Strategies against This Versatile Bacterial Pathogen.

Escherichia coli (E. coli) is a gram-negative bacillus and resident of the normal intestinal microbiota. However, some E. coli strains can cause diseases in humans, other mammals and birds ranging from intestinal infections, for example, diarrhea and dysentery, to extraintestinal infections, such as urinary tract infections, respiratory tract infections, meningitis, and sepsis. In terms of morbidity and mortality, pathogenic E. coli has a great impact on public health, with an economic cost of several billion dollars annually worldwide. Antibiotics are not usually used as first-line treatment for diarrheal illness caused by E. coli and in the case of bloody diarrhea, antibiotics are avoided due to the increased risk of hemolytic uremic syndrome. On the other hand, extraintestinal infections are treated with various antibiotics depending on the site of infection and susceptibility testing. Several alarming papers concerning the rising antibiotic resistance rates in E. coli strains have been published. The silent pandemic of multidrug-resistant bacteria including pathogenic E. coli that have become more difficult to treat favored prophylactic approaches such as E. coli vaccines. This review provides an overview of the pathogenesis of different pathotypes of E. coli, the virulence factors involved and updates on the major aspects of vaccine development against different E. coli pathotypes.

Cosa fare nella diarrea ematica? Tutto e niente?

We present the case of a 7-year-old boy with 2 days’ fever and diarrhea, who starts to present hemorrhagic diarrhea. He was evaluated in the Emergency Department and hospitalized. Campylobacter and Norovirus have been isolated on stool. During hospitalization, the patient was treated with intravenous rehydration and antipyretics, with rapid clinical improvement and discharge on the third day of hospitalization. A review of the literature shows that hemorrhagic enteritis is a frequent condition in children, with different etiologies depending on age. In children older than one year of age, the first cause is infective, of viral or bacterial origin. Generally, supportive care is sufficient in consideration of good prognosis of the infections. The use of antibiotics generally does not change outcomes; in some cases, it can even be harmful. The regional protocol for the management of hemorrhagic diarrhea in the Puglia region will be presented, with the aim of early identification of STEC infections, given their clinical relevance in the evolutionary risk of haemolytic uremic syndrome.

Review of Escherichia coli O157:H7 Prevalence, Pathogenicity, Heavy Metal and Antimicrobial Resistance, African Perspective.

Escherichia coli O157:H7 is an important food-borne and water-borne pathogen that causes hemorrhagic colitis and the hemolytic-uremic syndrome in humans and may cause serious morbidity and large outbreaks worldwide. People with bloody diarrhea have an increased risk of developing serious complications such as acute renal failure and neurological damage. The hemolytic-uremic syndrome (HUS) is a serious condition, and up to 50% of HUS patients can develop long-term renal dysfunction or blood pressure-related complications. Children aged two to six years have an increased risk of developing HUS. Clinical enteropathogenic Escherichia coli (EPEC) infections show fever, vomiting, and diarrhea. The EPEC reservoir is unknown but is suggested to be an asymptomatic or symptomatic child or an asymptomatic adult carrier. Spreading is often through the fecal-oral route. The prevalence of EPEC in infants is low, and EPEC is highly contagious in children. EPEC disease in children tends to be clinically more severe than other diarrheal infections. Some children experience persistent diarrhea that lasts for more than 14 days. Enterotoxigenic Escherichia coli (ETEC) strains are a compelling cause of the problem of diarrheal disease. ETEC strains are a global concern as the bacteria are the leading cause of acute watery diarrhea in children and the leading cause of traveler’s diarrhea. It is contagious to children and can cause chronic diarrhea that can affect the development and well-being of children. Infections with diarrheagenic E. coli are more common in African countries. Antimicrobial agents should be avoided in the acute phase of the disease since studies showed that antimicrobial agents may increase the risk of HUS in children. The South African National Veterinary Surveillance and Monitoring Programme for Resistance to Antimicrobial Drugs has reported increased antimicrobial resistance in E. coli. Pathogenic bacterial strains have developed resistance to a variety of antimicrobial agents due to antimicrobial misuse. The induced heavy metal tolerance may also enhance antimicrobial resistance. The prevalence of antimicrobial resistance depends on the type of the antimicrobial agent, bacterial strain, dose, time, and mode of administration. Developing countries are severely affected by increased resistance to antimicrobial agents due to poverty, lack of proper hygiene, and clean water, which can lead to bacterial infections with limited treatment options due to resistance.

Escherichia coli 0157:H7 virulence factors and the ruminant reservoir.

This review updates recent findings about Escherichia coli O157:H7 virulence factors and its bovine reservoir. This Shiga toxin (Stx)-producing E. coli belongs to the Enterohemorrhagic E. coli (EHEC) pathotype causing hemorrhagic colitis. Its low infectious dose makes it an efficient, severe, foodborne pathogen. Although EHEC remains in the intestine, Stx can translocate systemically and is cytotoxic to microvascular endothelial cells, especially in the kidney and brain. Disease can progress to life-threatening hemolytic uremic syndrome (HUS) with hemolytic anemia, acute kidney failure, and thrombocytopenia. Young children, the immunocompromised, and the elderly are at the highest risk for HUS. Healthy ruminants are the major reservoir of EHEC and cattle are the primary source of human exposure. Advances in understanding E. coli O157:H7 pathogenesis include molecular mechanisms of virulence, bacterial adherence, type three secretion effectors, intestinal microbiome, inflammation, and reservoir maintenance. Many aspects of E. coli O157:H7 disease remain unclear and include the role of the human and bovine intestinal microbiomes in infection. Therapeutic strategies involve controlling inflammatory responses and/or intestinal barrier function. Finally, elimination/reduction of E. coli O157:H7 in cattle using CRISPR-engineered conjugative bacterial plasmids and/or on-farm management likely hold solutions to reduce infections and increase food safety/security.

Interventions for Shiga toxin-producing Escherichia coli gastroenteritis and risk of hemolytic uremic syndrome: A population-based matched case control study.

The role of antibiotics in the treatment of Shiga toxin-producing Escherichia coli (STEC) infection is controversial. To evaluate the association between treatment (antibiotics, antidiarrheal agents, and probiotics) for STEC infection and hemolytic uremic syndrome (HUS) development. We performed a population-based matched case-control study using the data from the National Epidemiological Surveillance of Infectious Diseases (NESID) between January 1, 2017 and December 31, 2018. We identified all patients with STEC infection and HUS as cases and matched patients with STEC infection without HUS as controls, with a case-control a ratio of 1:5. Further medical information was obtained by a standardized questionnaire. Multivariable conditional logistic regression model was used. 7760 patients with STEC infection were registered in the NESID. 182 patients with HUS and 910 matched controls without HUS were selected. 90 patients with HUS (68 children and 22 adults) and 371 patients without HUS (266 children and 105 adults) were included in the main analysis. The matched ORs of any antibiotics and fosfomycin for HUS in children were 0.56 (95% CI 0.32-0.98), 0.58 (0.34-1.01). The matched ORs for HUS were 2.07 (1.07-4.03), 0.86 (0.46-1.61) in all ages treated with antidiarrheal agent and probiotics. Antibiotics, especially fosfomycin, may prevent the development of HUS in children, while use of antidiarrheal agents should be avoided.

Improving Care for Children with Bloody Diarrhea at Risk for Hemolytic Uremic Syndrome.

Children with infectious bloody diarrhea are at an increased risk for developing hemolytic uremic syndrome (HUS). Early intervention may improve outcomes. This study evaluated the impact of a clinical pathway designed to identify those at risk for HUS, guide initial management, and provide decision support regarding patient disposition. We performed a retrospective cohort study of children 4 months to 19 years of age who presented with the acute onset of bloody diarrhea or other HUS risk factors to the pediatric emergency department (ED) from September 2015 through July 2020. A rapid stool polymerase chain reaction (PCR) test became available in May 2017. The clinical pathway was implemented in January 2018. We used Fisher's exact tests and statistical process control charts to analyze patient- and system-level changes following pathway implementation. Three hundred five patients were included. Postimplementation, stool PCR use increased (78%-91%), hospitalization decreased (49%-30%), and mean total charges decreased ($7715-$6797). There were increases in length of stay (226-288 minutes) and charges ($2651-$3524) for patients discharged from the ED. All changes met rules for special cause variation. There was no change in early IV fluid administration, inpatient length of stay, ED return visits, hospital readmissions, or patients with Shiga toxin-producing Escherichia coli (STEC), acute kidney injury (AKI) or HUS. For children presenting to the ED with bloody diarrhea, introduction of a rapid stool PCR test and clinical pathway correlated with decreased hospitalizations and overall costs without adverse clinical outcomes.

Infliximab rescue therapy in a patient with acute severe ulcerative colitis and coronavirus disease 2019 followed by Escherichia coli 0157:H7 infection: a case report

The management of patients with acute severe ulcerative colitis and SARS-CoV-2 presents a clinical challenge. We report on the first case of a patient with acute severe ulcerative colitis and mild coronavirus disease 2019 (COVID-19) who received rescue infliximab therapy, followed by a relapse caused by enterohemorrhagic Escherichia coli 0157:H7. The treatment challenges we faced were biologic therapy administration during active COVID-19, about which little was known at the time, and how to treat EHEC due to the risk of hemolytic uremic syndrome. Acute severe ulcerative colitis was treated with rescue infliximab therapy, and enteric infection with an antibiotic, both with satisfactory clinical response. The decision to induce biologic therapy for inflammatory bowel disease relapse in SARS-CoV-2-positive patients should be made on a case-to-case basis and should be driven by the dominant disease. Our patient tested positive for SARS-CoV-2, but actually had mild disease. At the same time, she had acute severe ulcerative colitis, so we started anti-tumor necrosis factor therapy despite serological tests and the recommendation to delay biological therapy administration for two-weeks. Second, due to severity of the first flare, COVID-19, and the patient's general condition, we opted for an antibiotic treatment of Escherichia coli 0157:H7 while monitoring the parameters of potential hemolytic uremic syndrome development.

Analysis of scenarios to reduce the probability of acquiring hemolytic uremic syndrome associated with beef consumption.

The objective of this study was to develop a quantitative microbial risk assessment (QMRA) model to evaluate potential risk mitigation strategies to reduce the probability of acquiring hemolytic uremic syndrome (HUS) associated with beef consumption in Argentina. Five scenarios were simulated to evaluate the effect of interventions on the probability of acquiring HUS from Shiga toxin-producing Escherichia coli (STEC)-contaminated ground beef and commercial hamburger consumption. These control strategies were chosen based on previous results of the sensitivity analysis of a baseline QMRA model. The application of improvement actions in abattoirs not applying Hazard Analysis and Critical Control Points (HACCP) for STEC would result 7.6 times lower in the probability that consumers acquired HUS from ground beef consumption, while the implementation of improvements in butcher shops would lead to a smaller reduction. In abattoirs applying HACCP for STEC, the risk of acquiring HUS from commercial hamburger consumption was significantly reduced. Treatment with 2% lactic acid, hot water and irradiation reduced 4.5, 3.5 and 93.1 times the risk of HUS, respectively. The most efficient interventions, in terms of case reduction, being those that are applied in the initial stages of the meat chain.

Gut-Kidney Axis on Chip for Studying Effects of Antibiotics on Risk of Hemolytic Uremic Syndrome by Shiga Toxin-Producing Escherichia coli.

Shiga toxin-producing Escherichia coli (STEC) infects humans by colonizing the large intestine, and causes kidney damage by secreting Shiga toxins (Stxs). The increased secretion of Shiga toxin 2 (Stx2) by some antibiotics, such as ciprofloxacin (CIP), increases the risk of hemolytic–uremic syndrome (HUS), which can be life-threatening. However, previous studies evaluating this relationship have been conflicting, owing to the low frequency of EHEC infection, very small number of patients, and lack of an appropriate animal model. In this study, we developed gut–kidney axis (GKA) on chip for co-culturing gut (Caco-2) and kidney (HKC-8) cells, and observed both STEC O157:H7 (O157) infection and Stx intoxication in the gut and kidney cells on the chip, respectively. Without any antibiotic treatment, O157 killed both gut and kidney cells in GKA on the chip. CIP treatment reduced O157 infection in the gut cells, but increased Stx2-induced damage in the kidney cells, whereas the gentamycin treatment reduced both O157 infection in the gut cells and Stx2-induced damage in the kidney cells. This is the first report to recapitulate a clinically relevant situation, i.e., that CIP treatment causes more damage than gentamicin treatment. These results suggest that GKA on chip is very useful for simultaneous observation of O157 infections and Stx2 poisoning in gut and kidney cells, making it suitable for studying the effects of antibiotics on the risk of HUS.

Risk of Hemolytic Uremic Syndrome Related to Treatment of Escherichia coli O157 Infection with Different Antimicrobial Classes.

Treatment of Shiga toxin-producing Escherichia coli O157 (O157) diarrhea with antimicrobials might alter the risk of hemolytic uremic syndrome (HUS). However, full characterization of which antimicrobials might affect risk is lacking, particularly among adults. To inform clinical management, we conducted a case-control study of residents of the FoodNet surveillance areas with O157 diarrhea during a 4-year period to assess antimicrobial class-specific associations with HUS among persons with O157 diarrhea. We collected data from medical records and patient interviews. We measured associations between treatment with agents in specific antimicrobial classes during the first week of diarrhea and development of HUS, adjusting for age and illness severity. We enrolled 1308 patients; 102 (7.8%) developed confirmed HUS. Antimicrobial treatment varied by age: <5 years (12.6%), 5–14 (11.5%), 15–39 (45.4%), ≥40 (53.4%). Persons treated with a β-lactam had higher odds of developing HUS (OR 2.80, CI 1.14–6.89). None of the few persons treated with a macrolide developed HUS, but the protective association was not statistically significant. Exposure to “any antimicrobial” was not associated with increased odds of HUS. Our findings confirm the risk of β-lactams among children with O157 diarrhea and extends it to adults. We observed a high frequency of inappropriate antimicrobial treatment among adults. Our data suggest that antimicrobial classes differ in the magnitude of risk for persons with O157 diarrhea.

Structure of Enterohemorrhagic Escherichia coli O157:H7 Intimin Virulence Factor Bound to Nanobodies

Enterohemorrhagic E. coli O157:H7 (EHEC) is a food and water-born pathogen that presents a significant risk to human health worldwide. EHEC naturally resides in the intestinal tract of cattle as normal flora but can be transmitted to humans when contaminated food is ingested. Once EHEC invades and colonizes the human intestinal tract, it secretes Shiga-like toxins causing serious and potentially fatal gastrointestinal diseases. Unlike most foodborne bacterial diseases, antibiotics are not recommended for treatment of EHEC as antibiotics can induce enterotoxin release, increasing the risk of hemolytic uremic syndrome. There is currently no effective treatment or vaccine against enterohemorrhagic E. coli. EHEC pathogenicity involves intimin, a virulence factor which mediates bacterial colonization of the host GI tract. Due to its critical role in EHEC pathogenesis, intimin has attracted attention as an antibacterial drug target. Inhibiting the interaction of intimin with its cognate bacterial secreted receptor Tir could neutralize bacterial colonization of the gastrointestinal tract. One novel solution for treating EHEC infection comes from a unique class of antibodies known as nanobodies. Nanobodies are the antigen binding domain of heavy chain antibodies produced by the Camelid family. Intimin specific nanobodies were generated by immunizing a llama followed by phage display and selection for high affinity intimin binding nanobodies. The resultant intimin-specific nanobodies neutralized EHEC in vitro. We hypothesize that nanobodies specifically bind the Tir-binding domain of intimin in order to neutralizing EHEC infection. The goal of this research project is to determine the complex crystal structure of the nanobodies bound to intimin. The structure of nanobodies-intimin would show their protein-protein interaction binding site revealing key amino acids involved in binding. These residues could also be involved in the binding of intimin to its natural ligand, Tir. Thus, revealing such residues could form the bases for identifying and developing novel therapeutics and biosensors for treating and preventing EHEC pathogenesis.We show through size exclusion chromatography that nanobodies bind intimin and form stable complexes. We have set up crystal trails of five nanobodies (Int1, Int2, Int3, Int4, and IntN1) complexed to intimin. Two of the five complexed proteins, Int2-intimin and Int3-intimn formed crystals. The crystal condition for the two protein complexes Int2 and Int3 bound to intimin were optimized by varying the concentration of precipitants and pH range. Crystals of the protein complexes were sent to the Canadian Light Source for X-ray diffraction data collection. Diffraction measurements of Int2-intimin and Int3-intimin complexes were collected and processed in space groups P1 and P222, respectively. Currently, we are analyzing the structure by molecular replacement.

Hemoglobinuria for the early identification of STEC-HUS in high-risk children: data from the ItalKid-HUS Network.

Hemolytic uremic syndrome (HUS) represents one of the main causes of severe acute kidney injury in children. The most frequent form of HUS is caused by Shiga toxin-2 (Stx2)-producing Escherichia coli. Hemoglobinuria and hematuria are markers of glomerular damage, but their use has never been validated in HUS. We retrospectively analyzed the presence of hemoglobinuria/urinary red blood cells (RBCs) in children with Stx2-positive bloody diarrhea (BD) or with already ongoing STEC-HUS with the aim of validating its role in early identifying HUS. We reviewed all the pediatric patients with Stx2+ BD (group 1) and with ongoing HUS (group 2) referred to our center from 2010 to 2019. A total of 100 children were eligible for the study. In group 1, 22 patients showed hemoglobinuria/hematuria, while 41 remained negative. In 15/22 positive patients (68.2%), blood tests ruled in HUS, while in 7 (31.8%), HUS was excluded. Among the 41 patients persistently negative for hemoglobinuria/hematuria, no one developed HUS. The 37 STEC-HUS children (group 2) all had hemoglobinuria/RBCs at admission.Conclusion: Hemoglobinuria/hematuria for the diagnosis of HUS in children with Stx2+ BD showed a sensitivity of 100% and a specificity of 85%. We strongly recommend patients with BD carrying Stx2 in stools to be closely monitored with urine dipstick/urinalysis to early identify HUS. What is Known • Children with bloody diarrhea secondary to Shiga toxin 2 are at high risk of hemolytic uremic syndrome, thus have to be carefully monitored for the development of the disease, in order to early be hospitalized and treated. What is New • Urine dipstick for hemoglobinuria can be used as an easy, inexpensive, and repeatable tool to early diagnose children with bloody diarrhea secondary to Shiga toxin 2 to have developed hemolytic uremic syndrome, with no risk of false-negative results.

717. Antibiotic treatment of Shiga toxin-producing Escherichia coli related gastroenteritis and the risk of hemolytic uremic syndrome: a population based matched case-control study in Japan

BackgroundThe role of therapeutic intervention, particularly antibiotics, for Shiga toxin-producing Escherichia coli (STEC) related infection is controversial.MethodsWe performed a population based matched case-control study to assess the association between treatment (antibiotics, antidiarrheal agents and probiotics) for STEC related infections and HUS development. We identified all STEC HUS patients as cases and matched five non-HUS patients as controls using the data from the National Epidemiological Surveillance of Infectious Diseases (NESID) between January 1, 2017, and December 31, 2018. Further medical information was obtained by standardized questionnaires answered by physicians who registered each patient. We used multivariate conditional logistic regression model to evaluate the association between exposures (use of antibiotics, use of antidiarrheal agents, days between disease onset and fosfomycin administration [within two or three days]) and the development of HUS, by matched odds ratios (OR) and 95% confidence intervals (CI). Covariates we used were sex, age group, area code, presence of diarrhea and other factors. We also performed subgroup analyses using age (adults and children) as a stratification factor.Results7,760 STEC related patients were registered in the NESID. We selected patients who had a record of HUS diagnosis (n=182) and matched controls without HUS (n=910). After collecting standardized paper-based questionnaires, we enrolled 90 HUS patients and 371 non-HUS patients for analysis. In the main analysis, matched OR of fosfomycin was 0.75(0.47-1.20) in all ages, 1.41(0.51-3.88) in adults and 0.58(0.34-1.01) in children. Matched OR of antidiarrheal agents was 2.07(1.07-4.03) in all ages, 1.84(0.32-10.53) in adults, 2.65(1.21-5.82) in children. Matched OR of probiotics was 0.86(0.46-1.61) in all ages, 0.76(0.21-2.71) in adults, 1.00(0.48-2.09) in children. There was no significant association between the timing of fosfomycin use in the first two or five days of illness and HUS development in any age group.ConclusionOur results suggest that fosfomycin might decrease the risk of HUS in children younger than 15 years of age with STEC confirmed bacterial gastroenteritis.Disclosures All Authors: No reported disclosures

Risk Factors for HUS With Shiga Toxin–ProducingE coliDiarrhea

Research Article| September 01 2020 Risk Factors for HUS With Shiga Toxin–Producing E coli Diarrhea AAP Grand Rounds (2020) 44 (3): 31. https://doi.org/10.1542/gr.44-3-31 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Risk Factors for HUS With Shiga Toxin–Producing E coli Diarrhea. AAP Grand Rounds September 2020; 44 (3): 31. https://doi.org/10.1542/gr.44-3-31 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search toolbar search search input Search input auto suggest filter your search All PublicationsAll JournalsAAP Grand RoundsPediatricsHospital PediatricsPediatrics In ReviewNeoReviewsAAP NewsAll AAP Sites Search Advanced Search Topics: diarrhea, hemolytic-uremic syndrome, shiga-toxigenic escherichia coli Source: McKee RS, Schnadower D, Tarr PI, et al. Predicting hemolytic uremic syndrome and renal replacement therapy in Shiga toxin-producing Escherichia coli–infected children. Clin Infect Dis. 2020; 70(8): 1643– 1651; doi: https://doi.org/10.1093/cid/ciz432Google Scholar Investigators from multiple institutions conducted a retrospective study to identify risk factors for development of hemolytic uremic syndrome (HUS) in children with Shiga toxin–producing E coli (STEC) gastroenterits. Study participants were identified by review of microbiologic testing results from 38 medical centers in the US and Canada with pediatric EDs. Patients with STEC, seen in an ED at a participating site who did not have HUS at their initial ED visit, were enrolled. The medical records of study children were reviewed, and demographic, clinical, and laboratory data were abstracted. The primary study outcome was development of HUS, defined as: hematocrit <30%, platelet count <150 × 103/μL, and serum creatinine (Cr) above upper limit of normal for age. The association of multiple clinical and laboratory characteristics with development of HUS was assessed in bivariate analyses using chi-square and Mann-Whitney U tests. Logistic regression was used to identify independent predictors for HUS. A total of 927 patients with STEC were identified; 41 had HUS at the time of the initial ED visit and were excluded. Of the remaining 866 children, HUS developed in 126 (14.2%). On bivariate analysis, risk factors statistically associated with HUS included fever, reduced oral intake and urine output, hematochezia, vomiting, receipt of antibiotics, and ill appearance. Lower median values for serum sodium and bicarbonate, higher lactate dehydrogenase, blood urea nitrogen, white blood cell count (WBC), and C-reactive protein levels also were risk factors for HUS. In the multivariate analysis, younger age (odds ratio [OR] 0.77 per year increase; 95% CI, 0.69, 0.85), higher hematocrit (OR 1.83 for every 5% increase; 95% CI, 1.21, 2.77), WBC >13 × 103/μL (OR 2.54; 95% CI, 1.42, 4.54), platelet count <250 × 103/μL (OR 1.92; 95% CI, 1.02, 3.60), elevated Cr (OR 10.82 for every 1 mg/dL increase; 95% CI, 1.49, 78.69), low serum sodium (OR 1.12 for every 1 mmol/L decrease; 95% CI, 1.02, 1.23), and receipt of IV fluid >4 days after start of diarrhea (OR 2.50; 95% CI, 1.14, 5.46) were identified as independent predictors of HUS. A longer time from start of diarrhea to ED visit (OR 0.70 per day; 95% CI, 0.54, 0.90) was associated with reduced HUS risk. The authors conclude that the risk factors for developing HUS highlight the importance of avoiding dehydration and close clinical and laboratory monitoring in children with STEC infections. Dr Brady has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device. In 2019, the CDC investigated STEC outbreaks associated with salad kits, romaine lettuce, flour, bison, and ground beef.1 E coli O157:H7, the STEC most often implicated in outbreaks, is associated with the development... You do not currently have access to this content.

A Novel Tail-Associated O91-Specific Polysaccharide Depolymerase from a Podophage Reveals Lytic Efficacy of Shiga Toxin-Producing Escherichia coli.

Shiga toxin-producing Escherichia coli (STEC) strains are important zoonotic foodborne pathogens, causing diarrhea, hemorrhagic colitis, and life-threatening hemolytic uremic syndrome (HUS) in humans. However, antibiotic treatment of STEC infection is associated with an increased risk of HUS. Therefore, there is an urgent need for early and effective therapeutic strategies. Here, we isolated lytic T7-like STEC phage PHB19 and identified a novel O91-specific polysaccharide depolymerase (Dep6) in the C terminus of the PHB19 tailspike protein. Dep6 exhibited strong hydrolase activity across wide ranges of pH (pH 4 to 8) and temperature (20 to 60°C) and degraded polysaccharides on the surface of STEC strain HB10. In addition, both Dep6 and PHB19 degraded biofilms formed by STEC strain HB10. In a mouse STEC infection model, delayed Dep6 treatment (3 h postinfection) resulted in only 33% survival, compared with 83% survival when mice were treated simultaneously with infection. In comparison, pretreatment with Dep6 led to 100% survival compared with that of the control group. Surprisingly, a single PHB19 treatment resulted in 100% survival in all three treatment protocols. Moreover, a significant reduction in the levels of proinflammatory cytokines was observed at 24 h postinfection in Dep6- or PHB19-treated mice. These results demonstrated that Dep6 or PHB19 might be used as a potential therapeutic agent to prevent STEC infection.IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen worldwide. The Shiga-like toxin causes diarrhea, hemorrhagic colitis, and life-threatening hemolytic uremic syndrome (HUS) in humans. Although antibiotic therapy is still used for STEC infections, this approach may increase the risk of HUS. Phages or phage-derived depolymerases have been used to treat bacterial infections in animals and humans, as in the case of the "San Diego patient" treated with a phage cocktail. Here, we showed that phage PHB19 and its O91-specific polysaccharide depolymerase Dep6 degraded STEC biofilms and stripped the lipopolysaccharide (LPS) from STEC strain HB10, which was subsequently killed by serum complement in vitro In a mouse model, PHB19 and Dep6 protected against STEC infection and caused a significant reduction in the levels of proinflammatory cytokines. This study reports the use of an O91-specific polysaccharide depolymerase for the treatment of STEC infection in mice.

Escherichia coli O80 hybrid pathotype strains producing Shiga toxin and ESBL: molecular characterization and potential therapeutic options.

Enterohaemorrhagic Escherichia coli (EHEC) infections may be complicated by haemolytic uraemic syndrome (HUS). The emerging worldwide EHEC serogroup O80 has acquired a mosaic plasmid combining extraintestinal virulence and antibiotic resistance. This hybrid pathotype is associated with invasive infections that require antibiotic therapy, classically not recommended in EHEC infections, increasing the risk of HUS. We characterized two ESBL-producing O80 EHEC strains, which is an unusual resistance mechanism among EHECs, and determined the safest therapy to be used for invasive infections. WGS of two strains isolated from the stools of an asymptomatic carrier and a patient with HUS was performed using Illumina and Nanopore technologies. Generated reads were combined to assemble genomes. We determined the safest therapy by comparing Shiga toxin (Stx) production by the two strains in the presence of several antibiotics. The strains were genetically close to the O80 EHEC clone, belonging to ST301 and harbouring stx2d, eae-ξ, ehxA and genes characteristic of the extraintestinal virulence plasmid pS88. Long-read sequencing identified the acquisition of an additional plasmid harbouring CTX-M-type genes (blaCTX-M-14 and blaCTX-M-1). Azithromycin decreased Stx production at subinhibitory concentrations, ciprofloxacin increased it and imipenem had no major effect. The combination of azithromycin and imipenem overall reduced Stx production. Acquisition of an additional plasmid harbouring ESBL genes is a step towards increasing the risk of O80 EHEC dissemination and represents a serious public health concern. The combination of azithromycin and imipenem reduced Stx production and suggests that this combination could be tested in clinical trials.

Contribution and Interaction of Shiga Toxin Genes to Escherichia coli O157:H7 Virulence.

Escherichia coli O157:H7 is the predominant cause of diarrhea-associated hemolytic uremic syndrome (HUS) worldwide. Its cardinal virulence traits are Shiga toxins, which are encoded by stx genes, the most common of which are stx1a, stx2a, and stx2c. The toxins these genes encode differ in their in vitro and experimental phenotypes, but the human population-level impact of these differences is poorly understood. Using Shiga toxin-encoding bacteriophage insertion typing and real-time polymerase chain reaction, we genotyped isolates from 936 E. coli O157:H7 cases and verified HUS status via chart review. We compared the HUS risk between isolates with stx2a and those with stx2a and another gene and estimated additive interaction of the stx genes. Adjusted for age and symptoms, the HUS incidence of E. coli O157:H7 containing stx2a alone was 4.4% greater (95% confidence interval (CI) −0.3%, 9.1%) than when it occurred with stx1a. When stx1a and stx2a occur together, the risk of HUS was 27.1% lower (95% CI −87.8%, −2.3%) than would be expected if interaction were not present. At the population level, temporal or geographic shifts toward these genotypes should be monitored, and stx genotype may be an important consideration in clinically predicting HUS among E. coli O157:H7 cases.

Shiga toxin producing Escherichia coli-associated diarrhea and hemolytic uremic syndrome in young children in Romania

BackgroundDiarrheagenic Escherichia coli (E. coli) is an important cause of diarrheal diseases in both developing countries and industrialized countries. An outbreak of hemolytic uremic syndrome (HUS) in young children from southern Romania was reported in early 2016 and was attributed to Shiga toxin producing E. coli (STEC) O26 infection. The aim of this study was to determine the prevalence, demographic and clinical characteristics of STEC infections in children hospitalized with diarrhea in Brașov in the central region of Romania. We also described the occurrence of HUS among hospitalized children, close in time to the 2016 HUS outbreak in southern Romania.MethodsA prospective study was conducted between March and December 2016 among 722 children aged 1–30 months hospitalized with acute diarrhea. Stool samples obtained from patients with diarrhea were tested for the presence of Shiga toxin type 1 (STX1) and type 2 (STX2) by an immunochromatographic assay, and other enteropathogens. Demographic and clinical information on cases of HUS diagnosed in the same hospital was obtained from medical records.ResultsOverall 46/722 (6.4%) children (mean age 10.3 months, 32.6% females) hospitalized with diarrhea tested positive for STX1 or STX2; of these 79% were positive for both STX1 and STX2, 16% for STX2 only, and 5% for STX1 only. Bloody diarrhea, vomiting and fever were documented in 32.6%, 52.1% and 50.0%, respectively of patients with STEC infection. Eleven confirmed HUS cases (mean age 20 months, five females) were identified between 2014 and 2016 with prodromal diarrhea reported in 10 of them. Three of the 11 HUS patients required hemodialysis.ConclusionsSTEC prevalence among young children with diarrhea in Romania was high and the risk of HUS is emerging. The establishment of a systematic laboratory-based surveillance program including identification of the circulating STEC strains coupled with epidemiological investigation of HUS patients is warranted to determine the source and mode of transmission of STEC and prevent of STEC-associated diarrhea and HUS.

Predicting Hemolytic Uremic Syndrome and Renal Replacement Therapy in Shiga Toxin-producing Escherichia coli-infected Children.

Shiga toxin-producing Escherichia coli (STEC) infections are leading causes of pediatric acute renal failure. Identifying hemolytic uremic syndrome (HUS) risk factors is needed to guide care. We conducted a multicenter, historical cohort study to identify features associated with development of HUS (primary outcome) and need for renal replacement therapy (RRT) (secondary outcome) in STEC-infected children without HUS at initial presentation. Children aged <18 years who submitted STEC-positive specimens between January 2011 and December 2015 at a participating study institution were eligible. Of 927 STEC-infected children, 41 (4.4%) had HUS at presentation; of the remaining 886, 126 (14.2%) developed HUS. Predictors (all shown as odds ratio [OR] with 95% confidence interval [CI]) of HUS included younger age (0.77 [.69-.85] per year), leukocyte count ≥13.0 × 103/μL (2.54 [1.42-4.54]), higher hematocrit (1.83 [1.21-2.77] per 5% increase) and serum creatinine (10.82 [1.49-78.69] per 1 mg/dL increase), platelet count <250 × 103/μL (1.92 [1.02-3.60]), lower serum sodium (1.12 [1.02-1.23 per 1 mmol/L decrease), and intravenous fluid administration initiated ≥4 days following diarrhea onset (2.50 [1.14-5.46]). A longer interval from diarrhea onset to index visit was associated with reduced HUS risk (OR, 0.70 [95% CI, .54-.90]). RRT predictors (all shown as OR [95% CI]) included female sex (2.27 [1.14-4.50]), younger age (0.83 [.74-.92] per year), lower serum sodium (1.15 [1.04-1.27] per mmol/L decrease), higher leukocyte count ≥13.0 × 103/μL (2.35 [1.17-4.72]) and creatinine (7.75 [1.20-50.16] per 1 mg/dL increase) concentrations, and initial intravenous fluid administration ≥4 days following diarrhea onset (2.71 [1.18-6.21]). The complex nature of STEC infection renders predicting its course a challenge. Risk factors we identified highlight the importance of avoiding dehydration and performing close clinical and laboratory monitoring.

Human monocytes stimulated by Shiga toxin 1a via globotriaosylceramide release proinflammatory molecules associated with hemolytic uremic syndrome

The life-threatening sequela of hemorrhagic colitis induced by Shiga toxins (Stx)-producing Escherichia coli (STEC) infections in humans is hemolytic uremic syndrome (HUS), the main cause of acute renal failure in early childhood. The key step in the pathogenesis of HUS is the appearance of Stx in the blood of infected patients because these powerful virulence factors are capable of inducing severe microangiopathic lesions in the kidney. During precocious toxemia, which occurs in patients before the onset of HUS during the intestinal phase, Stx bind to several different circulating cells. An early response of these cells might include the release of proinflammatory mediators associated with the development of HUS. Here, we show that primary human monocytes stimulated with Shiga toxin 1a (Stx1a) through the glycolipid receptor globotriaosylceramide released larger amounts of proinflammatory molecules (IL-1β, TNFα, IL-6, G-CSF, CXCL8, CCL2, CCL4) than Stx1a-treated neutrophils. The mediators (except IL-1β) are among the top six proinflammatory mediators found in the sera from patients with HUS in different studies. The molecules appear to be involved in different pathogenetic steps of HUS, i.e. sensitization of renal endothelial cells to the toxin actions (IL-1β, TNFα), activation of circulating monocytes and neutrophils (CXCL8, CCL2, CCL4) and increase in neutrophil counts in patients with poor prognosis (G-CSF). Hence, a role of circulating monocytes in the very early phases of the pathogenetic process culminating with HUS can be envisaged. Impairment of the events of precocious toxemia would prevent or reduce the risk of HUS in STEC-infected children.