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H Chart

Publications and source records attributed to H Chart.

At least 19 recordsLinked to original sources
PubMed2002

Heterogeneity in expression of lipopolysaccharide by strains of Salmonella enterica serotype Typhimurium definitive phage type 104 and related phage types.

AIMS: To investigate lipopolysaccharide (LPS) expression in Salmonella enterica serotype Typhimurium definitive phage type 104 (Salmonella Typhimurium DT104) and related phage types. METHODS AND RESULTS: Isolates were examined for the expression of LPS by SDS-PAGE and silver staining and subtyped by Pulsed Field Gel Electrophoresis (PFGE). The 100 isolates expressed one of two LPS profiles designated A (72%) and B (28%). LPS profiling was able to discriminate between isolates of identical PFGE type. Among 10 groups of outbreak isolates examined, each group was of a single LPS profile: A, 8/10 and B, 2/10. All 10 outbreaks were identical by PFGE analysis. CONCLUSIONS: Isolates of Salmonella Typhimurium DT104 and related phage types expressed one of two distinct LPS profiles. The two LPS profiles appear similar but shifted and in phase with one another, suggesting that the heterogeneity is due to changes in the LPS core region rather than among the repeating oligosaccharide units of the long-chain LPS. SIGNIFICANCE AND IMPACT OF THE SUTDY: LPS profiling provides a useful adjunct to PFGE and other molecular methods for the subtyping of this group of bacteria in epidemiological investigations.

Bacteriophage Typing↗
PubMed2001

Vero cytotoxin binding to polymorphonuclear leukocytes among households with children with hemolytic uremic syndrome.

Hemolytic uremic syndrome (HUS), the leading cause of acute renal failure in childhood, can be caused by different serotypes of vero cytotoxin (VT; i.e., Shiga toxin)-producing Escherichia coli (VTEC). Recently, VT was shown to bind to polymorphonuclear leukocytes (PMNL) in the systemic circulation of patients with HUS. This study investigated whether VT bound to PMNL could be detected in persons in households with patients with HUS. Serum antibodies against E. coli O157 and, when available, fecal samples from patients with HUS and household members were studied for the presence of VTEC infection. The circulating PMNL of 82% of the household members were positive for VT, whereas stool and/or serum examination showed only 21% positivity. Thus, current methods underestimate the number of infected persons in households with patients with HUS.

Adult↗
PubMed2001

Human serum antibody response to Helicobacter pylori whole cell antigen in an institutionalized Bangladeshi population.

AIMS: To use a commercial ELISA kit and an immunoblot assay to investigate the antibody levels of selected members of the Bangladeshi population to Helicobacter pylori protein antigens. METHODS AND RESULTS: Using immunoblotting, high seroprevalence rates were observed in all age groups, although the subjects within the 1-9 years age group had the highest seroprevalence of antibodies to H. pylori antigens. By ELISA, the highest level of seroprevalence was observed in those over the age of 20 years. CONCLUSION: On the basis of these results the overall prevalence rate of H. pylori infection for the whole population was 77.4%; 77.9% for orphan boys and 76% for carers. CagA antibodies were detected in 86% of those with high levels of antibodies to H. pylori antigens. SIGNIFICANCE AND IMPACT OF THE STUDY: A combination of immunoblotting and ELISA was the most efficient means of detecting serum antibodies to H. pylori antigens and could be applied to the screening of human sera for H. pylori-specific antibodies.

Adolescent↗
PubMed2001

Development of a monoclonal sandwich ELISA for the detection of animal and human Escherichia coli O157 strains.

AIMS: Production of a monoclonal antibody (MAb) to Escherichia coli O157 to develop a rapid test using a sandwich ELISA (sELISA) format. METHODS AND RESULTS: A MAb (7A6) was developed to the long-chain lipopolysaccharide of E. coli O157. A sELISA developed with the MAb reacted with 28 bovine and seven human enterohaemorrhagic E. coli (EHEC) O157 strains and also with two enterotoxigenic E. coli O157 strains. Cross-reaction to a rabbit diarrhoeal E.coli O15, Citrobacter freundii, Salmonella urbana and Vibrio cholerae O1 Inaba was detected. CONCLUSION: A MAb-based sELISA to detect E. coli O157 was produced. Its application to field samples is required to fully determine its prospective use for the detection of EHEC O157, to evaluate the non-specific interference of the cross-reacting strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The assay produced is not wholly specific to EHEC O157, but has the potential to be used as a rapid method for screening large numbers of samples for E. coli O157.

Animals↗
PubMed2001

Evaluation of a reversed passive latex agglutination test for the detection of Verocytotoxin (VT) expressed by strains of VT-producing Escherichia coli.

AIMS: To compare an experimental Reversed-Passive Latex Agglutination (RPLA) with Vero cells for the detection of Verocytotoxin expressed by VT-producing strains of Escherichia coli (VTEC). METHODS AND RESULTS: The RPLA was used alongside a Vero cell tissue culture assay for the detection of VT in bacterial culture supernatant fluids and patients' faecal extracts. CONCLUSION: The RPLA was comparable with the Vero cell assay, although slightly less sensitive. SIGNIFICANCE AND IMPACT OF THE STUDY: The RPLA test proved to be a simple, rapid and convenient method of detecting VT in bacterial culture supernatant fluids and in the faeces of patients infected with VTEC.

Animals↗
PubMed2000

Evidence of persisting serum antibodies to Escherichia coli O157 lipopolysaccharide and Verocytotoxin in members of rural communities in England.

The techniques of enzyme-linked immunosorbent assay (ELISA) and immunoblotting were used to examine a total of 1667 sera, from apparently healthy members of rural communities in England, for antibodies to the lipopolysaccharide (LPS) of Escherichia coli O157 and Verocytotoxins (VT). Twenty-nine sera from 22 individuals were shown to have antibodies specific for E. coli O157 LPS. Some of these lived on livestock farms and had occupational contact with cattle, suggesting that personnel working with farm animals may produce serum antibodies to the O157 LPS antigens. Fifteen people had IgG class antibodies to O157 LPS, suggesting long-term exposure to E. coli O157 and five people had serum antibodies on more than one occasion showing evidence of persistent antibodies to O157 LPS. Thirteen sera from 12 of 22 individuals also contained antibodies to VT1, VT2 or both toxins. Ten sera contained antibodies to VT1 and VT2, three sera contained antibodies to VT2 only.

Adult↗
PubMed2000

An investigation into the pathogenic properties of Escherichia coli strains BLR, BL21, DH5alpha and EQ1.

AIMS: To examine Escherichia coli strains EQ1, DH5alpha, BLR and BL21 for known pathogenic mechanisms. METHODS AND RESULTS: Using specific DNA probes, the strains were shown not to carry the genes encoding invasion, various adhesion phenotypes or expression of a range of enterotoxins. The strains were unable to express long-chain lipopolysaccharide and were susceptible to the effects of serum complement. Using a BALB/c mouse model, the strains were shown to be unable to survive in selected tissues or to persist in the mouse gut. Using a chick model, strains EQ1, BLR and BL21 invaded livers but not spleens; only strain EQ1 persisted in the chick gut. In Merino sheep, only strain EQ1 was detected 6 d post-infection. CONCLUSIONS: Escherichia coli strains EQ1, DH5alpha, BLR and BL21 did not carry the well-recognized pathogenic mechanisms required by strains of E. coli causing the majority of enteric infections. SIGNIFICANCE AND IMPACT OF THE STUDY: Escherichia coli strains EQ1, DH5alpha, BLR and BL21 were considered to be non-pathogenic and unlikely to survive in host tissues and cause disease.

Animals↗
PubMed2000

The serodiagnosis of infection with Salmonella typhi.

BACKGROUND/AIMS: The serodiagnosis of infection with Salmonella typhi, using the Widal agglutination assay, relies on patients' antibodies to the O = 9,12 lipopolysaccharide (LPS) antigens, H = d flagellar antigens, and the Vi capsular antigens. A Vi agglutination titre of > 1/40 has traditionally been regarded as indicative of recent infection with S typhi. In this study, 91 sera were used to assess the reliability of the Widal agglutination assay based on antibodies to the Vi antigens. METHODS: The Widal agglutination assay was carried out using protocols established by the Central Public Health Laboratory, Colindale. Antibodies to the Vi capsular antigen were detected using a standard preparation of S typhi, ViI Bhatnagar variant strain (S typhi, ViI). Sera used in the study comprised 73 from patients who were culture positive for S typhi, 10 from patients who were culture positive for other species of Salmonella not expressing a Vi antigen (namely, S javiana, S enteritidis, S typhimurium, S stanley, S saint paul, S bareilly, or S mbandaka), and eight from healthy blood donors. RESULTS: Agglutination titres of > or = 1/40 were detected to S typhi ViI in 69 of 73 sera from patients with typhoid, although 27 of these also agglutinated an unrelated control antigen. The Widal assay also detected significant amounts of agglutinating antibodies to S. typhi ViI in all eight control sera and seven sera from patients infected with S bareilly, S enteritidis, S javiana, S mbandaka, S saint paul, and S stanley. CONCLUSIONS: Agglutinating antibodies to the Vi antigen can be detected by the Widal assay, but even with the appropriate control antigens the results were unreliable. The serodiagnosis of infections with S typhi should be based on the detection of antibodies to both the O = 9,12 LPS antigen and the H = d flagellar antigen by immunoblotting, and should not use the Vi antigen-based Widal assay. Conclusions should be made in the light of patients' clinical details and any knowledge of previous immunisation for typhoid.

Agglutination Tests↗
PubMed1999

Campylobacter coli strains with enlarged flagellin genes isolated from river water.

A group of campylobacters isolated from river water were found to possess unusually large flagellin genes. Both phenotype and serology were consistent with identification as Campylobacter coli. Phylogenetic analysis of small (16S, rrs) and large subunit (23S, rrl) rRNA genes of a representative strain, NCTC 13006, demonstrated high levels of relatedness with C. jejuni and C. coli (99.1 and 98.3% similarity for 16S; 99.3 and 99.4% similarity for 23S). Large flagellin proteins were demonstrated by SDS-PAGE analysis. The flaA and flaB genes were sequenced and aligned with known campylobacter flagellin amino acid sequences. The encoded FlaA protein of the new group exhibited a high degree of divergence from other Campylobacter species. Within the central variable region of FlaA, a further hypervariable domain was identified containing characteristic repeated motifs. Separate pairwise alignments performed for the variable regions of the polypeptide indicated these large fla genes were more closely related to those of C. upsaliensis than to those of C. coli or C. jejuni.

Amino Acid Sequence↗
PubMed1999

Characterization of enteroaggregative Escherichia coli isolated from outbreaks of diarrhoeal disease in England.

Twenty-two strains of enteroaggregative Escherichia coli (EAggEC), isolated from four outbreaks of diarrhoeal disease in England, were examined for a range of phenotypic attributes including the ability to produce fimbriae, haemolysins and siderophores, and cell-surface properties such as surface charge and hydrophobicity. Strains of EAggEC isolated from two of these outbreaks belonged to a diverse range of serotypes and were heterogeneous in phenotype. Strains of EAggEC isolated from the other two outbreaks belonged predominantly to serotypes 086:H34 and 098:H-, respectively. Only two strains expressed fimbriae and two strains produced an 18 kDa membrane associated protein (MAP), suggesting that EAggEC express a range of adhesion mechanisms to produce the cell arrangement recognized as the 'stacked brick' formation. The possible explanation for the diversity of EAggEC serotypes is discussed.

Bacterial Outer Membrane Proteins↗
PubMed1999

Serodiagnosis of infection with verocytotoxin-producing Escherichia coli.

Human sera (167) were screened for antibodies to lipopolysaccharide (LPS) prepared from strains of Verocytotoxin-producing Escherichia coli (VTEC) belonging to a range of serogroups, secreted proteins expressed by attaching and effacing VTEC, enterohaemolysin and H = 7 flagellar proteins. Twelve sera (about 7%) contained antibodies to the LPS of E. coli 05 (one), 026 (two), 0115 (two), 0145 (one), 0163 (one) and 0165 (five). Sera containing antibodies to the LPS of E. coli O26 and O145 also contained antibodies to secreted proteins of 100 and 40 kDa. An additional 34 sera, known to contain antibodies to the lipopolysaccharide of E. coli O157, were examined for antibodies to enterohaemolysin, H = 7 flagellar antigens and bacterial cell surface-associated proteins of 5, 6 and 22 kDa. Three sera contained antibodies to enterohaemolysin and one serum contained antibodies to flagellar proteins. Antibodies to membrane-associated proteins were not detected. It was concluded that enterohaemolysin, H = 7 flagellar proteins and the cell surface-associated proteins were unsuitable for use in immunoassays for providing evidence of infection with VTEC.

Adolescent↗
PubMed1999

The serodiagnosis of infections caused by Verocytotoxin-producing Escherichia coli.

Patients with haemolytic uraemic syndrome (HUS) and haemorrhagic colitis (HC) produce serum antibodies to the lipopolysaccharides (LPS) of Escherichia coli O157 and certain other E. coli serogroups. Patients may also make salivary antibodies to the LPS of E. coli O157. Serological tests based on these antibodies can be used to provide evidence of infection in the absence of culturable VTEC or the toxins they produce. Serum antibodies to LPS persist for several months following onset of disease, enabling both current and retrospective serological testing. The LPS of E. coli O157 shares epitopes with strains of Brucella abortus, Yersinia enterocolitica O9, Vibrio cholerae O1 Inaba, group N Salmonella and certain strains of Citrobacter freundii and E. hermanni. Serological tests for serum antibodies to E. coli O157 should be evaluated in the light of these cross-reactions. Serological tests to supply evidence of infection with E. coli O157 have been shown to provide a valuable adjunct to bacteriological procedures for detecting culturable VTEC and VT. The use of well characterized LPS antigens in association with the techniques of ELISA and immunoblotting provide valuable procedures for detecting evidence of infection with E. coli O157 and possibly other VTEC.

Antibodies, Bacterial↗
PubMed1999

Evaluation of a latex agglutination kit for the detection of human antibodies to the lipopolysaccharide of Escherichia coli O157, following infection with verocytotoxin-producing E. coli O157.

A total of 150 human sera was used to evaluate a commercial latex agglutination kit for detecting antibodies to the lipopolysaccharide of Escherichia coli O157. A comparison of the kit with SDS-PAGE and immunoblotting showed that the kit had a sensitivity of 94.12%, a specificity of 99.15%, a positive predictive value of 96.97% and a negative predictive value of 99.15%.

Adolescent↗
PubMed1999

Verocytotoxin-producing Escherichia coli infection in household members of children with hemolytic-uremic syndrome in The Netherlands.

BACKGROUND: Strains of verocytotoxin-producing Escherichia coli (VTEC) belonging to serogroup O157 (O157 VTEC) can cause a spectrum of disease that includes nonspecific diarrhea, hemorrhagic colitis and the diarrhea-associated form of the hemolytic uremic syndrome (D+ HUS). METHODS: We conducted a retrospective study of 34 children with D+ HUS caused by O157 VTEC to determine the frequency of VTEC infection in their household members. RESULTS: Gastrointestinal tract symptoms were reported in 1 or more household contacts of 17 (50%) of the 34 index cases. Of the 26 household members with gastrointestinal tract symptoms, 15 were parents and 11 were siblings. Evidence of VTEC infection was reported in 1 or more household contacts in 23 (68%) of the 34 families (in 46% of the siblings and in 28% of the parents). Nineteen (48%) siblings had a positive stool sample and in only 5 (12%) of the siblings IgM class serum antibodies to O157-lipopolysaccharide (LPS) were detected. Nineteen (31%) parents had a positive stool sample. Antibodies to O157-LPS were not detected in any of the parents. The occurrence of (bloody) diarrhea significantly correlated with the occurrence of IgM class serum antibodies to O157-LPS. CONCLUSIONS: It was concluded that household members of children with D+ HUS are often asymptomatically infected with O157 VTEC. Differences in the pathogenesis of the infection between infected individuals may be related to differences in the number of ingested O157 VTEC bacteria and to differences in susceptibility.

Antibodies, Bacterial↗