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H Chart

Publications and source records attributed to H Chart.

At least 37 records · Page 2Linked to original sources
PubMed1998

Expression of membrane-associated proteins by strains of enteroaggregative Escherichia coli.

Certain strains of enteroaggregative Escherichia coli express an outer membrane-associated protein, involved with the adhesion of these bacteria to HEp-2 cells. Strains of enteroaggregative E. coli hybridising with DNA probes for aggregative adhesion, diffuse adhesion and aggregative adhesion fimbriac II expressed an outer membrane-associated protein of 18 kDa regulated by magnesium ions. Strains hybridising with the aggregative adhesion probe only expressed a 20-kDa outer membrane-associated protein regulated by calcium and magnesium. The present study describes two populations of enteroaggregative E. coli which appear to adhere to HEp-2 cells by expressing antigenically distinct, negatively charged membrane-associated proteins.

Animals↗
PubMed1998

Serum antibodies to secreted proteins in patients infected with Escherichia coli O157 and other VTEC.

Certain strains of verotoxigenic Escherichia coli (VTEC), and in particular those belonging to serogroup O157, cause attaching and effacing (AE) lesions of the host gut mucosa during pathogenesis. The mechanisms involved with bacterial attachment and the destruction of microvilli are determined by a cluster of genes within the LEE region, which also encode five secreted proteins. Sera from patients with antibodies to the lipopolysaccharide (LPS) of E. coli O157 and other VTEC were tested for antibodies to these secreted proteins. Twenty-one of 34 (62%) sera with antibodies to the lipopolysaccharide (LPS) of E. coli O157 also contained antibodies to one or more of the secreted proteins. Five of 12 sera containing antibodies to the LPS of a range of other VTEC serogroups also contained antibodies to 1 or more of the 5 secreted proteins, as did 16 of 70 (23%) sera from patients with haemolytic uraemic syndrome (HUS), haemorrhagic colitis (HC) or diarrhoea, but without bacteriological evidence of infection with VTEC and which did not contain antibodies to VTEC serogroups O5, O115, O145, O153 or O157. The detection of serum antibodies to secreted proteins may provide additional information for interpreting the results of established lipopolysaccharide-based VTEC serology.

Antibodies, Bacterial↗
PubMed1998

Enteroaggregative Escherichia coli.

Enteroaggregative Escherichia coli (EAggEC) are a group of E. coli characterized by the ability to adhere to cultured cell monolayers with an aggregative or 'stacked brick' adhesion phenotype. These strains of E. coli are distinct from other pathogenic groups of E. coli. Epidemiological evidence suggests that strains of EAggEC are a significant cause of protracted diarrhoea in children, and may cause diarrhoea in adults. The group is heterogeneous, comprising a diverse range of serotypes that possess a variety of putative virulence factors. These include an enterotoxin similar to the heat-stable enterotoxin of enterotoxigenic E. coli, putative haemolysins and toxins, and various types of fimbriae and outer membrane proteins that may be involved in the adhesion process. The role of these factors in the production of disease is unclear. Diagnosis of EAggEC infection is problematic; serotyping alone cannot identify strains of E. coli expressing an EAggEC phenotype. Currently, EAggEC are identified by either cell adhesion tests or DNA-based tests involving gene probes or polymerase chain reaction (PCR) for detecting the genes encoding cell adhesion. The nature and significance of strains of E. coli expressing an EAggEC phenotype are poorly understood. This article reviews the current literature and speculates on the direction of future studies to define this emerging group of bacteria.

Adult↗
PubMed1998

Intra-strain variation in expression of lipopolysaccharide by Helicobacter pylori.

Intra-strain variation in the expression of lipopolysaccharide (LPS) by two clinical isolates of Helicobacter pylori was examined. Lipopolysaccharide was prepared from successive cultures of individual colonies from each strain, separated by SDS-PAGE, and detected by silver staining and by immunoblotting. The genetic 'relatedness' of the colonies was investigated using PCR-RFLP analysis of the urease and vacuolating cytotoxin genes. Although individual colonies of each of the two strains examined appeared to have the same genetic origins, variation in the expression of their long-chain LPS was observed. The same LPS profiles were maintained by individual colonies over four subcultures on solid media containing 10% (v/v) defibrinated horse blood.

Antigenic Variation↗
PubMed1998

Escherichia coli O157 serology: false-positive ELISA results caused by human antibodies binding to bovine serum albumin.

An analysis of farm workers and rural dwellers for serum antibodies to the lipopolysaccharide (LPS) of Escherichia coli O157 detected sera with antibodies binding to bovine serum albumin (BSA) by ELISA. These antibodies were not specific for BSA when examined by immunoblotting, and the ELISA values were reduced to a background level when plates were blocked with normal rabbit serum.

Animals↗
PubMed1998

An immunoblotting procedure comprising O = 9,12 and H = d antigens as an alternative to the Widal agglutination assay.

AIMS: To compare the established Widal agglutination assay with an immunoblotting procedure. METHODS: 110 sera were used to compare the established Widal agglutination assay with an immunoblotting procedure incorporating lipopolysaccharide (LPS) (O = 9,12) and flagellar (H = d) antigens. RESULTS: Antibodies to the LPS antigens were detected in 18 sera by the Widal assay and in 37 by immunoblotting. Antibodies to the flagellar antigens were detected in 27 sera by Widal assay and in 25 by immunoblotting. CONCLUSIONS: An immunoblotting procedure incorporating O = 9,12 LPS and H = d flagellar antigens was rapid and more sensitive than the established Widal agglutination assay for providing evidence of infection with S typhi.

Agglutination Tests↗
PubMed1998

The use of serodiagnosis in the retrospective investigation of a nursery outbreak associated with Escherichia coli O157:H7.

AIMS: To use serology to investigate an outbreak of verocytotoxin (VT) producing Escherichia coli O157 in a hospital nursery, following the detection of faecal E coli O157 (phage type 49) producing VT type 2. METHODS: ELISA and immunoblotting techniques, based on lipopolysaccharide (LPS) purified from E coli O157; diagnostic bacteriology; serotyping and phage typing; DNA probes for VT. RESULTS: 29 of 126 sera contained antibodies to the LPS of E coli O157: 10 were from children, three were from staff, and 11 were from hospital kitchen staff. Five parents of children attending the nursery were antibody positive. Sixty four sera from other hospital staff and controls did not contain antibodies to the LPS of E coli O157. CONCLUSIONS: Serology detected evidence of infection with E coli O157 in 23% of sera examined. By bacteriology alone, only a single case of infection with E coli O157 would have been detected. Serology is valuable in providing evidence of infection with E coli O157.

Antibodies, Bacterial↗
PubMed1998

Improved serological detection of infection with Vero cytotoxin producing Escherichia coli.

Vero cytotoxin producing Escherichia coli (VTEC)--including all those of serogroup O157--and enteropathogenic E. coli produce attaching and effacing lesions in gut epithelium. Immunoblotting was used to detect antibodies to secreted proteins associated with the formation of these lesions. These tests should provide additional evidence of VTEC infection in conjunction with current assays for antibioties to E. coli O157 lipopolysaccharide.

Bacterial Toxins↗
PubMed1997

Magnesium ions are required for HEp-2 cell adhesion by enteroaggregative strains of Escherichia coli O126:H27 and O44:H18.

Enteroaggregative strains of Escherichia coli, belonging to serotypes O44:H18 and O126:H27, were used to show that magnesium ions were essential for the adhesion of these enteroaggregative strains to HEp-2 cells. The removal of Mg2+ ions from culture media was correlated with the inability of strains to produce an outer membrane-associated protein of 18 kDa and a pellicle. It was concluded that magnesium ions were directly involved with the expression of an 18 kDa outer membrane-associated protein by strains of E. coli O126:H27 and O44:H18, and that the outer membrane-associated protein was involved in both HEp-2 adhesion and pellicle formation.

Antibody Specificity↗
PubMed1997

Identification of entero-aggregative Escherichia coli based on surface properties.

Twenty-nine strains of Escherichia coli that adhere to HEp-2 cells with a 'stacked brick' pattern (EAggEC), and four nonadherent control strains, were examined for the ability to hybridize with gene probes for aggregative (AA) and diffuse (DA) HEp-2 cell adhesion phenotypes. These strains were also tested for the ability to express an 18 kDa membrane-associated outer-membrane protein (MAP), to agglutinate erythrocytes, and to produce a pellicle during broth culture. Thirteen of the 29 HEp-2 adherent strains of E. coli hybridized with the gene probes for both AA and DA, and expressed an 18 kDa outer membrane protein (OMP) which was antigenically related to the MAP expressed by strains of E. coli O126:H27. The strains that did not carry the additional DA genes did not express an 18 kDa OMP. Although strains of EAggEC share the ability to adhere to HEp-2 cells with a stacked brick pattern, these strains exhibit a diverse range of physical and biochemical properties. From the results of this study, it was concluded that currently, the possession of EAggEC genes or the ability to adhere to HEp-2 cells in a stacked brick formation, remain the only reliable means of identifying EAggEC.

Bacterial Adhesion↗
PubMed1997

Serological response of patients infected with Salmonella typhi.

AIMS: To evaluate a rapid immunoblotting procedure for providing evidence of infection with Salmonella typhi using 73 sera from patients infected with S typhi. METHODS: A sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE)/immunoblotting procedure using lipopolysaccharide (LPS, O = 9,12) and flagellar (H = d) antigens was used. RESULTS: Seventy two of 73 sera contained antibodies to LPS, 40 sera also contained antibodies to H = d flagellar antigens. Analysis of acute and convalescent sera showed that only 62% of patients produced antibodies to flagellar antigens. CONCLUSIONS: The SDS-PAGE/immunoblotting procedure provided a rapid method for providing serological evidence of infection with S typhi.

Acute Disease↗
PubMed1996

Outer membrane characteristics of Campylobacter jejuni grown in chickens.

A type of in vivo phenotype of Campylobacter jejuni was obtained by maintaining bacteria in the peritoneal cavities of chickens for one week. These bacteria, which had not been subcultured on laboratory media, were used to prepare outer membranes for comparison with C. jejuni grown in vitro. Flagella with subunits of 65 kDa and a single porin with a protein subunit of 49 kDa were expressed constitutively; however, outer membrane proteins of 55, 35 and 20 kDa, and intermediate-chain lipopolysaccharide were only expressed by bacteria maintained in chickens.

Animals↗
PubMed1996

Verocytotoxin-producing Escherichia coli infection in hemolytic uremic syndrome in part of western Europe.

UNLABELLED: From September 1989 until September 1993, stool specimens and sera from 113 children with diarrhoea-associated haemolytic uraemic syndrome (HUS) from the Netherlands, two university hospitals in Belgium and one university hospital in Germany were examined for the presence of verocytotoxin-producing Escherichia coli (VTEC) infection. Evidence for VTEC infection was observed in 88 (78%) patients with HUS compared to 2 (3%) of the 65 children with acute gastro-enteritis Serotype O157 was the causative agent in 76 (86%) of these 88 patients with VTEC-associated HUS and verocytotoxin-2 (VT-2) was the most frequent toxin produced. Serological testing for antibodies to O157 O-antigen yielded the highest number of positive results compared to the other test methods. Antibodies to O157 were found in sera of 71 (65%) of 110 patients with HUS and one control serum. Stool and sera examination for VTEC in 95 family contacts of 28 patients with HUS demonstrated an evidence for VTEC infection 33 (35%). In contrast, in patients with HUS serological antibodies to O157 O-antigen were found in only 3 (4%) of 85 family contacts. CONCLUSION: In this part of Western Europe, VT2-producing Escherichia coli, mainly those belonging to serogroup O157, are the major cause of HUS in childhood.

Bacterial Toxins↗
PubMed1996

Vero cytotoxin-producing Escherichia coli, particularly serogroup O157, associated with human infections in England and Wales: 1992-4.

Investigations were performed by the Laboratory of Enteric Pathogens on Vero cytotoxin-producing Escherichia coli (VTEC) in England and Wales from 1992-4. Bacterial isolates, faeces and sera obtained from patients with diarrhoea, bloody diarrhoea and haemolytic uraemic syndrome were examined. Using serotyping, Vero cytotoxin gene probing and serodiagnostic tests for E. coli O157, evidence of infection was detected in 543, 434 and 491 individuals in 1992, 1993 and 1994 respectively; VTEC of serogroup O157 were isolated from 470, 385 and 411 cases. The O157 VTEC strains belonged to at least 19 different phage types (PT) although 84% belonged to PT2, PT49, PT8, PT1 or PT4. Antibodies to E. coli O157 lipopolysaccharide were detected in 13% of the cases. The average annual rate of infection with O157 VTEC was 0.83/100000 and 12% of the 1458 individuals with evidence of infection with VTEC or E. coli O157 developed haemolytic uraemic syndrome. There were at least 18 general outbreaks and many family outbreaks.

Adolescent↗
PubMed1996

Serum survival and plasmid possession by strains of Salmonella enteritidis, Salm. typhimurium and Salm. virchow.

Strains of Salmonella enteritidis, Salm. typhimurium and Salm. virchow, carrying different numbers of plasmids, were examined for the ability to multiply in sera. Viable counts were performed to monitor the kinetics of growth of bacteria when in human, chicken and turkey sera. The presence of plasmids in Salm. enteritidis, Salm. typhimurium and Salm. virchow reduced considerably the ability of strains of these serotypes to multiply in serum. SDS-PAGE was used to show that growth of Salm. enteritidis in serum did not involve changes in outer membrane proteins or lipopolysaccharide. It was concluded that the carriage of plasmids may be disadvantageous for the survival in serum of certain common salmonella serotypes.

Animals↗