Glycolipid receptors for verotoxin and Helicobacter pylori: role in pathology. (25/789)

Eukaryotic cell surface glycolipids can act as both the primary interface between bacteria and their host and secondly as a targeting mechanism for bacterial virulence factors. The former is characterized by redundancy in adhesin-receptor interactions and the latter by a higher affinity, more restrictive glycolipid binding specificity for targeting. Interactions of verotoxin with its glycolipid receptor globotriaosylceramide and Helicobacter pylori binding to a variety of different glycolipids, which can be environmentally regulated, provide examples of these differing modes of glycolipid receptor function. Verotoxins are involved in endothelial targeting in the microangiopathies of hemorrhagic colitis and hemolytic uremic syndrome (HUS). The highly restricted binding specificity and crystal structure of the verotoxin B subunit have allowed theoretical modeling of the Gb3 binding site of the verotoxin B subunit pentamer which provides an approach to intervention. Studies of the role of glycolipid function in verotoxin-induced disease have concentrated on the distribution of Gb3 and its ability to mediate the internalization of the toxin within the target cell. The distribution of Gb3 within the renal glomerulus plays a central role in defining the age-related etiology of HUS following gastrointestinal infection with VT producing Escherichia coli. H. pylori, on the other hand, instigates a less distinct but more complex disseminated gastric inflammation. Studies on the role of glycolipid receptors in H. pylori infection have been bogged down in establishing the importance of each binding specificity defined. In addition, the physiological condition of the organism within the various binding assays has not been extensively considered, such that spurious non-physiological interactions may have been elucidated. The identification and cloning of a Le(b) binding adhesin and the identification of cell surface hsp70 as a mediator of sulfoglycolipid binding under stress conditions may now allow a more molecular approach to define the role of glycolipid recognition in this infection.  (+info)

Complement factor H gene mutation associated with autosomal recessive atypical hemolytic uremic syndrome. (26/789)

Atypical hemolytic uremic syndrome (HUS) presents with the clinical features of hypertension, microangiopathic hemolytic anemia, and acute renal failure. Both dominant and recessive modes of inheritance have been reported. This study describes the genetic and functional analysis of a large Bedouin kindred with autosomal recessive HUS. The kindred consists of several related nuclear families in which all parent unions of affected children are consanguineous. A previous report demonstrated that a dominant form of HUS maps to chromosome 1q and that complement factor H (CFH), a regulatory component of the complement system, lies within the region and is involved in the dominant disorder. Early-onset and persistent hypocomplementemia in this Bedouin kindred prompted us to evaluate the CFH gene. Linkage analysis was performed, demonstrating linkage between the disorder and the markers near the CFH gene. Mutation analysis of the CFH coding region revealed a single missense mutation. Functional analyses demonstrate that the mutant CFH is properly expressed and synthesized but that it is not transported normally from the cell. This is the first study reporting that a recessive, atypical, early-onset, and relapsing HUS is associated with the CFH protein and that a CFH mutation affects intracellular trafficking and secretion.  (+info)

Pretreatment of mice with lipopolysaccharide (LPS) or IL-1beta exerts dose-dependent opposite effects on Shiga toxin-2 lethality. (27/789)

Haemolytic uraemic syndrome (HUS) has been closely associated with infection with a group of Shiga toxin-producing enterohaemorrhagic Eschericchia coli in young children. Shiga toxins (Stx) have been implicated as pathogenic agents of HUS by binding to the surface receptor of endothelial cells. LPS is a central product of the Gram-negative bacteria and several reports have documented that both LPS and Stx are important for disease development. In this study the reciprocal interactions between LPS and Stx2 are analysed in a mouse model. The results demonstrated that LPS was able to reduce or enhance Stx2 toxicity, depending on the dose and the timing of the injection. The involvement of the main early cytokines induced by LPS, tumour necrosis factor alpha (TNF-alpha) and IL-1beta, in those LPS opposite effects on Stx2 toxicity was evaluated. Stx2 toxicity was enhanced by in vivo injection of murine TNF-alpha and low doses of murine IL-1beta. However, at higher doses of IL-1beta which induced corticosteroid increase in serum, Stx2 lethality was decreased. Considering that dexamethasone and IL-1beta reproduce the LPS protective effects, it is suggested that endogenous corticosteroids secondary to the inflammatory response induced by LPS, mediate the protection against Stx2. It can be concluded that the fine equilibrium between proinflammatory and anti-inflammatory activities strongly influences Stx2 toxicity.  (+info)

A case of hemolytic uremic syndrome improved with nitric oxide. (28/789)

Hemolytic uremic syndrome (HUS) after transplantation is difficult to treat, and there is no consensus regarding optimal mode of treatment. We attached transdermal isosorbide tape as a nitric oxide (NO) donor to patients with HUS after bone marrow transplantation (BMT). This was very effective in ameliorating the hemolysis and increasing platelet numbers. We report here the successful use of an isosorbide in a patient with HUS after transplantation. Bone Marrow Transplantation (2000) 25, 109-110.  (+info)

An outbreak of Escherichia coli O157:H7 infections and haemolytic uraemic syndrome associated with consumption of unpasteurized apple cider. (29/789)

During October 1996, an outbreak of Escherichia coli O157:H7 infections among Connecticut residents occurred. An epidemiologic investigation included enhanced surveillance and a case-control study. Clinical isolates of Escherichia coli O157:H7 were typed by pulsed-field gel electrophoresis (PFGE). Implicated cider samples were analysed by culture and polymerase chain reaction (PCR). Consumption of implicated cider was associated with illness; (matched odds ratio = undefined, 95 % confidence interval = 3.5-infinity). Ultimately, a total of 14 outbreak-associated patients were identified. All isolates analysed by PFGE yielded the outbreak-associated subtype. Escherichia coli O157:H7 was not cultured from three cider samples; PCR analysis detected DNA fragments consistent with Escherichia coli O157:H7 in one. This outbreak was associated with drinking one brand of unpasteurized apple cider. PFGE subtyping supported the epidemiologic association. PCR analysis detected microbial contaminants in the absence of live organisms. Washing and brushing apples did not prevent cider contamination.  (+info)

Identification and characterisation of Escherichia coli strains of O157 and non-O157 serogroups containing three distinct Shiga toxin genes. (30/789)

Three Shiga toxin (Stx)-producing Escherichia coli (STEC) strains from patients with diarrhoea were identified, each of which contained three distinct stx genes (stx1, stx2 and stx2c). The strains belonged to the serotypes O52:H19, O75:H- and O157:H- and harboured eae and EHEC-hly sequences. Colony-blot immunoassay was used to demonstrate that both major types of Stx were expressed. The association of stx genes with either phage or phage DNA was demonstrated in all three strains. Isolated phage DNA from all strains contained stx1 sequences, but stx2 sequences were found only in phage DNA of two of these strains. The presence of three distinct stx genes may enhance the virulence of STEC strains and should be monitored. The observations demonstrate not only the potential of stx genes to spread within different serotypes, but also their capacity to accumulate within a single strain.  (+info)

Escherichia coli O157:H7; an economic assessment of an outbreak. (31/789)

BACKGROUND: The aim of the study was to assess the impact of an outbreak of Escherichia coli O157:H7 that occurred in 1994 in a rural community, with a population of approximately 107,000, to the west of Edinburgh. METHODS: The impact of the outbreak was assessed during the acute phase of the illness and in the subsequent 12 months. The method involved three surveys of confirmed cases using general practice notes, hospital records and interviews with cases. Key persons involved in the investigation and control of the outbreak were also interviewed. The impact of the illness on cases and their families was estimated and the resources used to treat cases and to control the outbreak were costed and long-term costs projected. RESULTS: There were 71 cases whose ages ranged from 7 months to 84 years. The mortality rate was 1.4 per hundred cases. There were 10 cases of haemolytic uraemic syndrome (HUS) and one case of thrombotic thrombocytopenia purpura (TTP). Two children were on long-term dialysis. Co-morbidity involving the immune system was associated with hospital admission. The illness lasted on average 6.9 weeks. Twenty-six per cent of cases reported symptoms 12 months later. The average cost per HUS case was 62,353 pound sterlings, the TTP case cost 21,422 pound sterlings, non-HUS and non-TTP cases cost 1,030 pound sterlings. The costs of investigating and controlling the outbreak were 171,848 pound sterlings. The costs of cases projected over 30 years were 11.9 million pound sterlings, or 168,032 pound sterlings per case. CONCLUSIONS: The impact on the health of cases was considerable and the costs were high. Every effort should be made to prevent the disease and to identify and control outbreaks quickly.  (+info)

Haemolytic uraemic syndrome and Shiga toxin-producing Escherichia coli infection in children in France. The Societe de Nephrologie Pediatrique. (32/789)

We conducted a study to determine the incidence of haemolytic uraemic syndrome (HUS) in children in France and to assess the role of Shiga-toxin-producing Escherichia coli (STEC) infection in the aetiology of HUS. In collaboration with the Societe de Nephrologie Pediatrique we undertook a retrospective review of all cases of HUS hospitalized from January 1993 to March 1995 and a 1-year prospective study (April 1995-March 1996) of epidemiological and microbiological features of cases of HUS. The polymerase chain reaction (PCR) procedure was used to detect stx, eae, e-hlyA genes directly from case stool samples. Serum samples from cases were examined for antibodies to lipopolysaccharide (LPS) of 26 major STEC serogroups. Two hundred and eighty-six cases were reported. The average incidence per year was 0.7/10(5) children < 15 years and 1.8/10(5) children < 5 years. During the prospective study, 122/130 cases were examined for evidence of STEC infection using PCR and/or serological assays and 105 (86%) had evidence of STEC infection. Serum antibodies to E. coli O157 LPS were detected in 79 (67%) cases tested. In conclusion, this study showed that STEC infection is an important cause of HUS in children in France, with a high proportion related to the O157 serogroup.  (+info)