Epidemic Escherichia coli O157:H7 gastroenteritis and hemolytic-uremic syndrome in a Canadian inuit community: intestinal illness in family members as a risk factor

Probiotics, prebiotics, and postbiotics in health and disease

The gut microbiota and its homeostasis play a crucial role in human health. However, for some diseases related to the gut microbiota, current traditional medicines can only relieve symptoms, and it is difficult to solve the root causes or even cause side effects like disturbances in the gut microbiota. Increasing clinical studies and evidences have demonstrated that probiotics, prebiotics, and postbiotics can prevent and treat various diseases, but currently they can only be used as dietary supplements rather than medicines, which restricts the application of probiotics in the field of medicine. Here, this review analyzes the importance of gut microbiota in human health and the current problems of traditional medicines, and systematically summarizes the effectiveness and mechanisms of probiotics, prebiotics, and postbiotics in maintaining health and treating diseases based on animal models and clinical trials. And based on current research outcomes and development trends in this field, the challenges and prospects of their clinical application in maintaining health, alleviating and treating diseases are analyzed. It is hoped to promote the application of probiotics, prebiotics, and postbiotics in disease treatment and open up new frontiers in probiotic research.

Climate Change and Enteric Infections in the Canadian Arctic: Do We Know What’s on the Horizon?

The Canadian Arctic has a long history with diarrheal disease, including outbreaks of campylobacteriosis, giardiasis, and salmonellosis. Due to climate change, the Canadian Arctic is experiencing rapid environmental transformation, which not only threatens the livelihood of local Indigenous Peoples, but also supports the spread, frequency, and intensity of enteric pathogen outbreaks. Advances in diagnostic testing and detection have brought to attention the current burden of disease due to Cryptosporidium, Campylobacter, and Helicobacter pylori. As climate change is known to influence pathogen transmission (e.g., food and water), Arctic communities need support in developing prevention and surveillance strategies that are culturally appropriate. This review aims to provide an overview of how climate change is currently and is expected to impact enteric pathogens in the Canadian Arctic.

Disinfection and removal of human pathogenic bacteria in arctic waste stabilization ponds

Wastewater stabilization ponds (WSPs) are commonly used to treat municipal wastewater in Arctic Canada. The biological treatment in the WSPs is strongly influenced by climatic conditions. Currently, there is limited information about the removal of fecal and pathogenic bacteria during the short cool summer treatment season. With relevance to public health, the objectives of this paper were to determine if treatment in arctic WSPs resulted in the disinfection (i.e., removal of fecal indicator bacteria, Escherichia coli) and removal of selected human bacterial pathogens from the treated effluent. The treatment performance, with focus on microbial removal, was assessed for the one-cell WSP in Pond Inlet (Nunavut [NU]) and two-cell WSP in Clyde River (NU) over three consecutive (2012-2014) summer treatment seasons (late June-early September). The WSPs provided a primary disinfection treatment of the wastewater with a 2-3 Log removal of generic indicator E. coli. The bacterial pathogens Salmonella spp., pathogenic E. coli, and Listeria monocytogenes, but not Campylobacter spp. and Helicobacter pylori, were detected in the untreated and treated wastewater, indicating that human pathogens were not reliably removed. Seasonal and annual variations in temperature significantly (p < 0.05) affected the disinfection efficiency. Improved disinfection and pathogen removal was observed for the two-cell system in Clyde River as compared to the one-cell system in Pond Inlet. A quantitative microbial risk assessment should be performed to determine if the release of low levels of human pathogens into the arctic environment poses a human health risk.

Foodborne and waterborne illness among Canadian Indigenous populations: A scoping review

Background

Indigenous populations are often at higher risk for foodborne illness than the general Canadian population.

Objective

To investigate the extent of the literature on the link between food safety and the occurrence of foodborne and waterborne illness in Canadian Indigenous populations.

Methods

A scoping review was conducted using search strings in five databases and grey literature to identify all papers that studied a Canadian Indigenous population and referred to any potential associations between food safety (including consumption and preparation of traditional foods and retail foods) or water safety practices and food or waterborne illness. Two authors screened papers based on inclusion and exclusion criteria. Included documents were analyzed for emergent themes.

Results

From 1,718 unique records identified, 21 documents were selected. Foodborne illness was most common in children up to 14 years old. Walrus, seal, caribou and whale were the most common traditional foods tied to foodborne illness and were primarily associated with botulism and trichinosis. Aside from consuming the food raw, fermentation was the most common traditional preparation method linked to foodborne illness. There was concern about the safety of retail food but no clear link was identified with foodborne illness. Lastly, although there was concern about tap water, the use of alternate water sources, such as untreated brook water, and hygiene and cleaning practices in communities with boil water advisories were the most common risk behaviours associated with waterborne illness.

Conclusion

Consumption of certain game meats, as well as the use of traditional fermentation practices may lead to an increased risk of foodborne illness among Indigenous populations. Concern about tap water may lead to use of unsafe alternate water sources. Further research is needed to examine potential culturally appropriate food and water safety opportunities.

Chronic sequelae of E. coli O157: systematic review and meta-analysis of the proportion of E. coli O157 cases that develop chronic sequelae

OBJECTIVE

This was a systematic review and meta-analysis to determine the proportion of Escherichia coli O157 cases that develop chronic sequelae.

DATA SOURCES

We conducted a systematic review of articles published prior to July 2011 in Pubmed, Agricola, CabDirect, or Food Safety and Technology Abstracts.

STUDY SELECTION

Studies were selected that reported the number of E. coli O157 cases that developed reactive arthritis (ReA), hemolytic uremic syndrome (HUS), irritable bowel syndrome, inflammatory bowel disease, or Guillain Barré syndrome.

METHODS

Three levels of screening and data extraction of articles were conducted using predefined data fields. Meta-analysis was performed on unique outcome measures using a random-effects model, and heterogeneity was assessed using the I² value. Meta-regression was used to explore the influence of nine study-level variables on heterogeneity.

RESULTS

A total of 82 studies were identified reporting 141 different outcome measures; 81 reported on HUS and one reported on ReA. Depending on the number of cases of E. coli O157, the estimate for the proportion of E. coli O157 cases that develop HUS ranged from 17.2% in extra-small studies (<50 cases) to 4.2% in extra-large studies (>1000 cases). Heterogeneity was significantly associated with group size (p<0.0001); however, the majority of the heterogeneity was unexplained.

CONCLUSIONS

High unexplained heterogeneity indicated that the study-level factors examined had a minimal influence on the variation of estimates reported.

Nanolitre real-time PCR detection of bacterial, parasitic, and viral agents from patients with diarrhoea in Nunavut, Canada

Background

Little is known about the microbiology of diarrhoeal disease in Canada's Arctic regions. There are a number of limitations of conventional microbiology testing techniques for diarrhoeal pathogens, and these may be further compromised in the Arctic, given the often long distances for specimen transport.

Objective

To develop a novel multiple-target nanolitre real-time reverse transcriptase (RT)-PCR platform to simultaneously test diarrhoeal specimens collected from residents of the Qikiqtani (Baffin Island) Region of Nunavut, Canada, for a wide range of bacterial, parasitic and viral agents.

Study design/methods

Diarrhoeal stool samples submitted for bacterial culture to Qikiqtani General Hospital in Nunavut over an 18-month period were tested with a multiple-target nanolitre real-time PCR panel for major diarrhoeal pathogens including 8 bacterial, 6 viral and 2 parasitic targets.

Results

Among 86 stool specimens tested by PCR, a total of 50 pathogens were detected with 1 or more pathogens found in 40 (46.5%) stool specimens. The organisms detected comprised 17 Cryptosporidium spp., 5 Clostridium difficile with toxin B, 6 Campylobacter spp., 6 Salmonella spp., 4 astroviruses, 3 noroviruses, 1 rotavirus, 1 Shigella spp. and 1 Giardia spp. The frequency of detection by PCR and bacterial culture was similar for Salmonella spp., but discrepant for Campylobacter spp., as Campylobacter was detected by culture from only 1/86 specimens. Similarly, Cryptosporidium spp. was detected in multiple samples by PCR but was not detected by microscopy or enzyme immunoassay.

Conclusions

Cryptosporidium spp., Campylobacter spp. and Clostridium difficile may be relatively common but possibly under-recognised pathogens in this region. Further study is needed to determine the regional epidemiology and clinical significance of these organisms. This method appears to be a useful tool for gastrointestinal pathogen research and may also be helpful for clinical diagnostics and outbreak investigation in remote regions where the yield of routine testing may be compromised.

Risk factors for severe cholera among children under five in rural and urban Bangladesh, 2000-2008: a hospital-based surveillance study

Background

Children under five bear the largest cholera burden. We therefore sought to identify modifiable risk factors among Bangladeshi children.

Methodology/Principal Findings

We used multivariate Poisson regression to assess risk factors for severe cholera among diarrheal patients presenting at hospitals in Matlab (rural) and Dhaka (urban), Bangladesh. Risk increased with age. Compared to those under one, rural and urban four-year-olds had adjusted risk ratios (aRR) of 4.17 (95% confidence interval (CI) 2.43–7.15) and 6.32 (95% CI: 4.63–8.63), respectively. Breastfeeding halved the risk in both rural (aRR = 0.49, 95% CI: 0.35–0.67) and urban (aRR = 0.51, 95% CI: 0.41–0.62) settings. Rural children’s risk decreased with maternal education (P-trend: <0.001) and increased among those with a family member with diarrhea in the past week (aRR = 1.61, 95% CI: 1.22–2.14) and those with prior vitamin A supplementation (aRR = 1.65, 95% CI: 1.12–2.43). Urban children whose mothers daily (aRR = 0.41, 95% CI: 0.21–0.79) or occasionally (aRR = 0.55, 95% CI: 0.36–0.84) read a newspaper experienced reduced risk. Urban children from households with incomes between 34–84 USD/month had a 30% increased risk compared to those from households with incomes >84 USD/month.

Conclusion/Significance

Increasing age, lower socioeconomic status, and lack of breastfeeding are key correlates of increased risk for cholera hospitalization among those under five in rural and urban Bangladesh. In addition, having a family member with diarrhea in the past week was associated with increased risk among rural children. Continued attention should be directed to the promotion of breastfeeding. Further research is needed to elucidate the relationship between maternal education and cholera risk. Renewed research regarding the use of chemoprophylaxis among family members of cholera cases may be warranted in rural endemic settings.

Antibody response to Shiga toxins in Argentinean children with enteropathic hemolytic uremic syndrome at acute and long-term follow-up periods

Shiga toxin (Stx)-producing Escherichia coli (STEC) infection is associated with a broad spectrum of clinical manifestations that include diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Systemic Stx toxemia is considered to be central to the genesis of HUS. Distinct methods have been used to evaluate anti-Stx response for immunodiagnostic or epidemiological analysis of HUS cases. The development of enzyme-linked immunosorbent assay (ELISA) and western blot (WB) assay to detect the presence of specific antibodies to Stx has introduced important advantages for serodiagnosis of HUS. However, application of these methods for seroepidemiological studies in Argentina has been limited. The aim of this work was to develop an ELISA to detect antibodies against the B subunit of Stx2, and a WB to evaluate antibodies against both subunits of Stx2 and Stx1, in order to analyze the pertinence and effectiveness of these techniques in the Argentinean population. We studied 72 normal healthy children (NHC) and 105 HUS patients of the urban pediatric population from the surrounding area of Buenos Aires city. Using the WB method we detected 67% of plasma from NHC reactive for Stx2, but only 8% for Stx1. These results are in agreement with the broad circulation of Stx2-expressing STEC in Argentina and the endemic behavior of HUS in this country. Moreover, the simultaneous evaluation by the two methods allowed us to differentiate acute HUS patients from NHC with a great specificity and accuracy, in order to confirm the HUS etiology when pathogenic bacteria were not isolated from stools.

Preventing household transmission of Shiga toxin-producing Escherichia coli O157 infection: promptly separating siblings might be the key

BACKGROUND

Preventing household transmission of Shiga toxin-producing Escherichia coli O157 (STEC O157) infection is important because of the ease of interpersonal transmission and the potential disease severity.

METHODS

We conducted a retrospective cohort study of households associated with an outbreak of STEC O157 infection in South Wales, United Kingdom, in autumn 2005. We investigated whether characteristics of the primary case patient or the household were predictors for secondary household transmission of STEC O157 infection. Furthermore, we estimated the proportion of cases that might be prevented by isolation (e.g., hospitalization) of the primary case patient immediately after the microbiological diagnosis and the number of patients with STEC O157 who would need to be isolated to prevent 1 case of hemolytic uremic syndrome. Based on dates of symptom onset, case patients in households were classified as having primary, coprimary, or secondary infection. Secondary cases were considered to be preventable if the secondary case patient's symptoms started >1 incubation period (4 days) after the date of microbiological diagnosis of the primary case.

RESULTS

Eighty-nine (91%) of 98 eligible households were enrolled. Among 20 households (22%), 25 secondary cases were ascertained. Thirteen secondary cases (56%) occurred in siblings of the primary case patients; hemolytic uremic syndrome developed in 4 of these siblings. Presence of a sibling (risk ratio, 3.8; 95% confidence interval, 0.99-14.6) and young age (<5 years) of the primary case patient (risk ratio, 2.03; 95% confidence interval, 0.99-41.6) were independent predictors for households in which secondary cases occurred. Of the 15 secondary cases for which complete information was available, 7 (46%) might have been prevented. When restricting isolation to primary case patients who were aged <10 years and who had a sibling, we estimated the number of patients who would need to be isolated to prevent 1 case of hemolytic uremic syndrome to be 47 patients (95% confidence interval, 16-78 patients).

CONCLUSIONS

Promptly separating pediatric patients with STEC O157 infection from their young siblings should be considered.

Variation in the persistence of Escherichia coli O157:H7 in experimentally inoculated 6-week-old conventional lambs

Six-week-old lambs were inoculated orally with 10(9) cfu of an antibiotic-resistance marked four-strain mixture of enterohaemorrhagic Escherichia coli (EHEC) O157:H7 to investigate faecal excretion and intestinal colonisation. In the first experiment, three E. coli O157:H7 isolates were not detected in the faeces of any lambs beyond day 8 post inoculation (pi), or from any of the tissues derived from inoculated animals. One strain, 140065 Nal(r), was isolated from the caecum and colon of one lamb on day 9 pi, from the rectum of another on day 22 pi and persisted in the faeces for up to 28 days pi. All animals remained clinically normal throughout the study period and histological evidence of adhesion of E. coli O157:H7 to the intestinal mucosa was not found. In a separate experiment, four 6-week-old lambs were inoculated orally with 10(9) cfu of E. coli O157:H7 strain 140065 Nal(r) alone. Faecal samples were positive for this strain until the end of the experiment (day 19 pi). This strain was also recovered from the gastrointestinal tract of lambs on days 6, 18 and 19 pi, but was not isolated at day 17 pi. When sampled separately, rectum and terminal colon contents contained higher numbers of the inoculated strain than the intestinal tissue at these sites. Animals inoculated with O157:H7 strain 140065 Nal(r) alone produced soft faeces from day 5 pi onwards. Although attaching and effacing lesions were observed in the caecum, proximal colon and rectum in one animal on day 18 pi, the adherent bacteria did not stain with antiserum raised against the O157 antigen.

Verotoxigenic Escherichia coli (VTEC): a major public health threat in Canada

BACKGROUND

Verotoxigenic Escherichia coli (VTEC) was first described in Canada during the 1980s as an emerging foodborne disease in association with morbidity and mortality in outbreaks of hemorrhagic colitis caused by E coli O157:H7.

OBJECTIVE

To describe the surveillance activities and epidemiological laboratory markers of VTEC that are used at the National Laboratory for Enteric Pathogens (NLEP) to investigate sporadic cases and outbreaks of E coli O157:H7 and non-O157 VTEC in Canada.

METHODS

Passive surveillance was conducted by obtaining data on laboratory confirmed cases of VTEC from the Provincial Laboratories of Public Health across Canada. The laboratory epidemiological markers generated for isolates of VTEC included biotyping, serotyping, phage typing, toxin detection and characterization, and molecular typing using pulsed-field gel electrophoresis.

RESULTS

Major outbreaks of VTEC O157:H7 disease have been associated with ground beef, unpasteurized apple juice, salami and untreated water. In 1999 and 2000, a total of 46 outbreaks of E coli O157:H7 disease were investigated. Among those, one outbreak was associated with contact at a petting zoo and a second with the consumption of salami. An outbreak in 2000 in Ontario was associated with water and resulted in more than 1000 cases of human illness, with six deaths. The NLEP has also identified more than 100 non-O157 VTEC serotypes from cattle and meat products. At least 23 VTEC serotypes found in humans were also identical to those found in cattle and meat products.

CONCLUSIONS

The laboratory-based information that is generated is used to define the incidence, sources of infection, risk factors, trends, distribution and transmission of VTEC to humans from food, water and animal sources. Prevention and control of outbreaks are high-priority health concerns.

Shiga toxin-producing Escherichia coli infection and antibodies against Stx2 and Stx1 in household contacts of children with enteropathic hemolytic-uremic syndrome

Ninety-five household contacts (aged 2 months to 73 years) of patients with enteropathic hemolytic-uremic syndrome (HUS) were investigated for the presence of immunoglobulin (Ig) G antibodies to Shiga toxins Stx2 and Stx1 by Western blot assay. Thirty-one percent of the household contacts and 19% of 327 controls had anti-Stx2 IgG (heavy and light chain [H + L]), 5 and 8%, respectively, had anti-Stx1 IgG (H + L), and 3 and 2%, respectively, had both anti-Stx2 and anti-Stx1 IgG (H + L). The incidence of infections with Stx-producing Escherichia coli (STEC) was determined based on the following diagnostic criteria: STEC isolation, detection of stx gene sequences, free fecal Stx in stool filtrates, and serum IgM antibodies against E. coli O157 lipopolysaccharide. Evidence of STEC infection was observed in 25 household contacts, of whom 18 (72%) were asymptomatic and represented a potential source of infection. Six of 13 (46%) household contacts with Stx2-producing E. coli O157:H7 in stool culture developed anti-Stx2 IgG (H + L), compared to 71% of Stx2-associated HUS cases. In individuals showing anti-Stx2 IgG (H + L), the antibody response was directed against the B subunit in 69% of household contacts and 71% of controls, in contrast to 28% of HUS patients. In this investigation controls had a significant increase of the median of IgM antibodies to O157 lipopolysaccharide (LPS) with age, up to the fifth decade. The lack of disease in household contacts with B subunit-specific antibodies, as well as the significantly higher median of anti-O157 LPS IgM antibodies in controls beyond 4.9 years of age, suggests a protective role for anti-Stx and anti-O157 LPS antibodies.

Localization of Shiga toxins of enterohaemorrhagic Escherichia coli in kidneys of paediatric and geriatric patients with fatal haemolytic uraemic syndrome

Haemolytic uraemic syndrome (HUS) is characterized by haemolytic anaemia, thrombocytopenia and renal failure. Infection with enterohaemorrhagic Escherichia coli (EHEC), mainly O157:H7, has been strongly implicated as the major cause of HUS in children. The pathogenesis of HUS caused by the infection is not well understood and the defined sites of Stx in kidney of EHEC-infected humans has not been clearly demonstrated. The aim of this study was to investigate and compare the locations of Stx deposition in kidneys of paediatric and geriatric patients who died from enterohaemorrhagic E. coli O157 (EHEC) associated HUS, using an immunoperoxidase staining of the tissues. The study revealed that binding of Stx was relatively less and limited only to the renal tubules of an adult case (81 years old), while more binding was found at both renal tubules and glomeruli of an infant case (21 months old). The Stx binding in the infant's glomeruli was at podocytes, mesangial and endothelial cells. It has been known that young children are more susceptible than adults to HUS. One possibility for this is that the more extensive binding of the Stx to the kidney tissue of the paediatric patient might be due to the higher synthesis and expression of Stx receptors, i.e. Gb(3), in infants and less so in the aged individuals. However, other alternatives are possible, for example, the difference in stage of HUS in individual patients. Thus it is too early to draw any conclusion on this enigma and further investigation is required.

Shigella and Shiga toxin-producing Escherichia coli causing bloody diarrhea in Latin America

In Latin America, Shigella and shiga toxin-producing Escherichia coli are the two leading agents in the cause of bloody diarrhea. The already high and increasing antimicrobial resistance of Shigella also is a significant problem. Shiga toxin-producing E. coli is an emerging disease with life-threatening complications: hemolytic uremic syndrome. Although E. coli O157:H7 remains the most commonly recognized serotype, recently emerging, non-O157 bacteria may be the cause of a similar spectrum of disease in humans.

Bovine colostrum ameliorates diarrhea in infection with diarrheagenic Escherichia coli, shiga toxin-producing E. Coli, and E. coli expressing intimin and hemolysin

BACKGROUND

Diarrheagenic Escherichia coli may cause serious extraintestinal complications, but there is no specific treatment.

METHODS

Patients with diarrhea caused by diarrheagenic E. coli, specifically Shiga toxin-producing E. coli and E. coli-expressing intimin and enterohemorrhagic E. coli-hemolysin were treated by administration of pooled bovine colostrum, rich in antibodies to Shiga toxin and enterohemorrhagic E. coli-hemolysin, in a placebo-controlled, double-blind study. Symptom resolution and fecal excretion of infecting strains were assessed.

RESULTS

No side effects were attributable to colostrum. Stool frequencies in the group treated with bovine colostrum were significantly reduced compared with those in the placebo group. No effect of therapy on the carriage of the pathogens or on complications of the infection could be demonstrated.

CONCLUSIONS

Bovine colostrum is well tolerated and diminishes frequency of loose stools in children with E. coli-associated diarrhea. A prospective study should be conducted among a larger number of children with Shiga toxin-producing E. coli identified early in illness, to determine the effectiveness of colostrum therapy.

Escherichia coli O157:H7

Escherichia coli O157 was first identified as a human pathogen in 1982. One of several Shiga toxin-producing serotypes known to cause human illness, the organism probably evolved through horizontal acquisition of genes for Shiga toxins and other virulence factors. E. coli O157 is found regularly in the faeces of healthy cattle, and is transmitted to humans through contaminated food, water, and direct contact with infected people or animals. Human infection is associated with a wide range of clinical illness, including asymptomatic shedding, non-bloody diarrhoea, haemorrhagic colitis, haemolytic uraemic syndrome, and death. Since laboratory practices vary, physicians need to know whether laboratories in their area routinely test for E. coli O157 in stool specimens. Treatment with antimicrobial agents remains controversial: some studies suggest that treatment may precipitate haemolytic uraemic syndrome, and other studies suggest no effect or even a protective effect. Physicians can help to prevent E. coli O157 infections by counselling patients about the hazards of consuming undercooked ground meat or unpasteurised milk products and juices, and about the importance of handwashing to prevent the spread of diarrhoeal illness, and by informing public-health authorities when they see unusual numbers of cases of bloody diarrhoea or haemolytic uraemic syndrome.

Shiga toxin 1 elicits diverse biologic responses in mesangial cells

BACKGROUND

Shiga toxin 1 (Stx1) is a causative agent in hemolytic uremic syndrome (HUS). Its receptor, the glycosphingolipid globotriaosylceramide (Gb3), is expressed on cultured human endothelial and mesangial cells. Mesangial cell injury in HUS ranges from mild cellular edema to severe mesangiolysis and eventual glomerulosclerosis. We hypothesized that, in addition to endothelial cells, mesangial cells are targets of Stx1.

METHODS

Human mesangial cells were exposed to Stx1. Protein synthesis was measured using [35S]-methionine/cysteine. Cell viability was measured as the lysosomal uptake of Neutral Red. Monocyte chemotactic peptide (MCP-1) mRNA and protein were analyzed by Northern blotting and ELISA.

RESULTS

Stx1 (0.25 to 2500 ng/ml) resulted in a dose-dependent inhibition of protein synthesis. This effect of Stx1 was potentiated by preincubation of the cells with interleukin-1alpha (IL-1alpha; 2 ng/ml) or tumor necrosis-alpha (TNF-alpha; 500 U/ml). Stx1 had little effect on mesangial cell viability during the first 24 hours of exposure to Stx1. However, prolonged incubation with Stx1 for 48 and 72 hours resulted in a 68% and 80% decrease in cell-viability, respectively. Stx1 elicited a dose and time dependent increase in the levels of MCP-1 mRNA, an effect that was potentiated by preincubation with IL-1alpha.

CONCLUSION

These data indicate that mesangial cells are susceptible to the effects of Stx1 in vitro. Stx1 exerts a spectrum of biologic effects on mesangial cells ranging from activation of chemokine genes to a lethal toxic injury. Immunoinflammatory cytokines potentiate the effects of Stx1. Thus, glomerular pathology in HUS may also result from a direct effect of Stx1 on mesangial cells.

Risk of hemolytic uremic syndrome after sporadic Escherichia coli O157:H7 infection: results of a Canadian collaborative study. Investigators of the Canadian Pediatric Kidney Disease Research Center

OBJECTIVES

The objectives of this study were to better estimate the age-specific risks of hemolytic uremic syndrome (HUS) and hemolytic anemia after Escherichia coli O157:H7 infection among a representative cohort of both referred and nonreferred children with documented illness from the province of Alberta and to compare this with the rates in children evaluated at referral centers in the rest of Canada.

STUDY DESIGN

Children with HUS or E. coli O157:H7 gastroenteritis were eligible if they were < 15 years of age. Hemoglobin, blood smear, urinalysis, and serum creatinine were obtained 8 to 10 days after the onset of diarrhea to ascertain for hemolysis, anemia, thrombocytopenia, and renal injury. Subjects were monitored for 1 month.

RESULTS

From June 1991 to March 1994, HUS was diagnosed in 205 children. Of these 77% had evidence of E. coli O157:H7 infection. A further 582 children had E. coli O157:H7 gastroenteritis, of whom 18 had hemolytic anemia. The risk of HUS after E. coli O157:H7 infection in Alberta was 8.1% (95% confidence interval, 5.3 to 11.6) compared with 31.4% in referral centers in the rest of Canada. In Alberta the highest age-specific risk of HUS/hemolytic anemia was 12.9% in those < 5 years of age.

CONCLUSIONS

These data will help guide clinical care and provide a basis for estimating the sample sizes required in future treatment trials for the secondary prevention of HUS.

Diarrheagenic Escherichia coli

Escherichia coli is the predominant nonpathogenic facultative flora of the human intestine. Some E. coli strains, however, have developed the ability to cause disease of the gastrointestinal, urinary, or central nervous system in even the most robust human hosts. Diarrheagenic strains of E. coli can be divided into at least six different categories with corresponding distinct pathogenic schemes. Taken together, these organisms probably represent the most common cause of pediatric diarrhea worldwide. Several distinct clinical syndromes accompany infection with diarrheagenic E. coli categories, including traveler's diarrhea (enterotoxigenic E. coli), hemorrhagic colitis and hemolytic-uremic syndrome (enterohemorrhagic E. coli), persistent diarrhea (enteroaggregative E. coli), and watery diarrhea of infants (entero-pathogenic E. coli). This review discusses the current level of understanding of the pathogenesis of the diarrheagenic E. coli strains and describes how their pathogenic schemes underlie the clinical manifestations, diagnostic approach, and epidemiologic investigation of these important pathogens.

Seasonality and other epidemiological features of haemolytic uraemic syndrome and E. coli O157 isolates in Scotland

The main objective was to determine whether there was seasonality in presentation of haemolytic uraemic syndrome (HUS) in children and adults, and compare this with the reporting of E. coli O157. The data came from Scotland, examining admissions during 1980-95 and E. coli isolates 1984-95. Seasonality was sought by fitting a sine curve to monthly or four-weekly data throughout the year. Seasonality was present for HUS and E. coli isolates in patients under 15 years of age but not in those above that age. The highest point of the sine curve was in July/August but there was a high plateau from June to September. The timing was similar to other diarrhoeal disease. This is an epidemiological study, the purpose being to clarify the seasonal features of HUS. E. coli infection is an important food hazard and a sound knowledge of the epidemiology, could lead to optimal control. The Scottish geographic distribution is illustrated.

Haemolytic-uraemic syndrome in the Hunter: public health implications

Three cases of haemolytic-uraemic syndrome in the Hunter area were reported in February 1995. An investigation was initiated to identify any verocytotoxic Escherichia coli in clinical samples that could be associated with the development of the disease. Escherichia coli O6:H- and O2:H7 were isolated from Case 1. No organisms were identified for Case 2, and Case 3 samples yielded Campylobacter jejuni. In addition, efforts were made to trace sources of any such pathogens in food samples or in the environment generally. Shiga-like toxins were found in meat products sampled from butchers' shops patronised by the families of the three cases. However, it was not found possible to match stool samples with samples of food from sources used by the families of the children. Environmental factors seemed likely to have played a significant role in the development of haemolytic-uraemic syndrome in Case 3. It is suggested that the incidence of the disease may be reduced by increasing the frequency of testing of meat products for Shiga-like toxins I and II and through educational and research programs.

[Digestive manifestations in hemolytic uremic syndrome in children]

BACKGROUND

Gastro-intestinal manifestations are relatively frequent during the course of hemolytic uremic syndrome (HUS), some of them requiring special supportive care. This work was aimed at retrospectively studing gastrointestinal manifestations of HUS and determining their place in the prognosis.

PATIENTS

Thirty-seven children aged 4 months to 11 years (22 girls and 15 boys) were included in the study.

RESULTS

All children but one had gastrointestinal prodromes. During the course of HUS, various manifestations were seen: bloody diarrhea in 32% of patients, ileo-ileal intussusception in 3%, rectal prolapse in 8% and hepatic cytolysis in 38%. Seven patients with bloody diarrhea had a complicated course, lethal in one. Comparison between these seven children and the 30 others revealed some indicators of severe gut involvement: female sex, short duration of gastrointestinal prodromes, hemorrhagic colitis with rectal prolapse, high WBC count, high neutrophils count and less important degree of anemia at admission. Severity of the gastrointestinal lesions was correlated with that of the outcome of the renal disease.

CONCLUSION

Gastrointestinal tract is frequently affected in HUS and severe complications can appear, potentially leading to death. Total parenteral nutrition could prevent occurrence of gastrointestinal complications. Severe gastrointestinal lesions are associated with a poor renal outcome.

Diarrhea in young children associated with Escherichia coli non-O157 organisms that produce Shiga-like toxin

OBJECTIVE

To assess the clinical manifestations and incidence of infection associated with Shiga-like toxin-producing Escherichia coli (SLTEC).

STUDY DESIGN

Children with diarrhea within a defined geographic area during a 12-month period were examined for the presence of SLTEC in their stools by polymerase chain reaction with the use of primers that were complementary to sequences of Shiga-like toxins types I and II and to other virulence factors.

RESULTS

There were 13 SLTEC infections among 468 children with diarrhea. Besides Shiga-like toxin sequences, the virulence genes eae and EHEC-hly were found in 10 isolates; these isolates were categorized as enterohemorrhagic E. coli (EHEC). Only 2 of 13 isolates were of the O157 strain. All reported cases occurred in summer (June through September) with the exception of one case in April. The infections were sporadic, and the infected children lived in rural and urban areas. Three infections in children with disabilities were hospital acquired. The majority of children had watery diarrhea, two had bloody diarrhea, and one had mild hemolytic-uremic syndrome. The overall incidence of SLTEC infection was 12.5 hospitalized children per 100,000 children less than 16 years of age.

CONCLUSIONS

The most frequent clinical manifestation of SLTEC infection was watery diarrhea indistinguishable from other forms of infectious diarrhea. The shift from the O157 strain toward non-O157 SLTEC strains associated with diarrhea, also observed in German patients with hemolytic-uremic syndrome, points to a change in the epidemiologic features of SLTEC-associated disease. Testing for non-O157 SLTEC should be considered in children with diarrhea without a recognized cause.

The hemolytic uremic syndrome

HUS is the most common cause of acute renal failure in infants and young children and follows a diarrheal prodrome about 90% of the time. Persuasive evidence shows that virtually all of postdiarrheal cases are caused by EHEC infections, and that the great majority of cases in the United States are caused by the EHEC serotype O157:H7. Mortality is approximately 5%, and approximately 10% of survivors are left with severe sequelae. A much larger number (30%-50%) experience mild chronic renal damage. Public health strategies, including zero tolerance for fecal contamination in slaughter houses and additional public education on proper food handling and cooking, does much to decrease the prevalence of the syndrome. Efforts to further dissect the postdiarrheal pathogenic cascade should continue, and an animal model needs to be developed. Only then will researchers be positioned to develop effective intervention strategies. Preventing life-threatening extrarenal complications, especially of the CNS, is a major challenge. Idiopathic nondiarrheal HUS accounts for approximately 10% of cases and comprises a poorly understood composite of HUS subsets. Research directed toward a better understanding of these mysterious variants also is a priority for the years ahead.

P1 blood group antigen expression and epidemic hemolytic uremic syndrome

P1 blood group positivity has been postulated as a host factor which may provide protection against the development of post-enteropathic hemolytic uremic syndrome (HUS). In this study, blood group status in 20 Inuit survivors of Escherichia coli O157:H7-associated HUS was compared with age- and sex-matched controls from the same community who had experienced uncomplicated diarrheal illness due to the same pathogen. Of 20 HUS survivors, 6 were P1 antigen positive compared with 8 of the 20 controls (P = 0.7). We conclude that P1 antigen positivity was not protective against HUS in this population. Further studies of this condition to clarify the role of host factors in verotoxin-induced endothelial damage are indicated.

Haemolytic-uraemic syndrome in childhood: surveillance and case-control studies in Italy. Italian HUS Study Group

Seventy-six cases of haemolytic-uraemic syndrome (HUS) were collected over a 4-year period during a surveillance and case-control study. The annual incidence of 0.2 per 100,000 children aged 0-14 years is lower than in other countries; 34% had no prodromal diarrhoea. Evidence for verocytotoxin-producing Escherichia coli (VTEC) infection was found in 72% of patients and 3% of controls; 88% of patients with bloody diarrhoea, 67% with non-bloody diarrhoea and 55% without diarrhoea were VTEC positive. Seventy-three percent of patients had creatinine clearance > or = 80 ml/min per 1.73 m2, normal blood pressure, no proteinuria and haematuria < 2+ after 1 year of follow-up. One patient died and none had non-renal sequelae. VTEC positivity was significantly correlated with a good outcome, while the absence of diarrhoea and a high total white blood cell count at onset were not predictors of a bad outcome. Household contacts of HUS patients had diarrhoea more frequently than those of the control group, supporting the hypothesis of person-to-person transmission of VTEC infection.