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H R Smith

Publications and source records attributed to H R Smith.

At least 127 records · Page 7Linked to original sources
PubMed1994

The detection of Vero cytotoxin-producing Escherichia coli and Shigella dysenteriae type 1 in faecal specimens using polymerase chain reaction gene amplification.

Fifty consecutive faecal specimens received by the LEP were examined for the presence of Vero cytotoxin (VT) genes by polymerase chain reaction (PCR) gene amplification. Nineteen were positive by PCR and from 16 of these, VT positive Escherichia coli O157 were isolated. The remaining three samples were positive for VT genes by PCR but VTEC were not isolated. In a preliminary experiment, Shigella dysenteriae type 1 was isolated from a case of bloody diarrhoea following a positive amplification result.

Bacterial Toxins↗
PubMed1994

Hybridization of strains of Escherichia coli O157 with probes derived from the eaeA gene of enteropathogenic E. coli and the eaeA homolog from a Vero cytotoxin-producing strain of E. coli O157.

A total of 375 Escherichia coli O157 strains were tested by colony hybridization with the eae probe from the central portion of the eaeA gene of the classical enteropathogenic E. coli strain E2348/69. They were also tested with a probe, eaeO157, from the C-terminal end of the eae gene homolog from a Vero cytotoxin (VT)-producing strain of E. coli (VTEC) of serotype O157:H7. Both probes hybridized with all 246 O157:H7 or H- VTEC strains tested. The majority were from human infections, and the remainder were from cattle. A further 10 strains (H7 or H-) hybridized with both eae and eaeO157 sequences but not with VT probes. They resembled O157 VTEC and were probably naturally occurring derivatives that had lost VT genes. The remaining 119 strains of O157 were from human, animal, and food sources and belonged to 16 H types other than H7 or were H-. They were VT negative and differed in their properties from O157 VTEC: generally they fermented sorbitol in 1 day, produced beta-glucuronidase, and could not be phage typed by the scheme for O157 VTEC. The eae probe but not the eaeO157 sequence hybridized with 18 H8 or H39 strains, predominantly from human diarrhea. The remaining 101 VT-negative strains hybridized with neither probe. However, 16 strains of O157:H45 hybridized with a probe for diffusely adherent E. coli and attached to HEp-2 cells in a diffuse pattern. Serogroup O157 comprises strains with heterogeneous properties. The eaeO157 probe is a valuable addition to the VT probes used to differentiate O157 strains.

Animals↗
PubMed1994

Familial Sneddon's syndrome: clinical, hematologic, and radiographic findings in two brothers.

We present the clinical, hematologic, and radiographic findings in two brothers with Sneddon's syndrome (stroke and livedo reticularis) and antiphospholipid antibodies. Patient 1 had anticardiolipin antibody and patient 2 had lupus anticoagulant, which we detected only upon repeated blood testing. One should test for both anticardiolipin antibody and lupus anticoagulant and repeat the screenings before determining a Sneddon's syndrome patient's antiphospholipid antibody status. Both Sneddon's syndrome and the primary antiphospholipid antibody syndrome are potentially familial causes of stroke. In familial cases, an inherited predisposition to antiphospholipid antibody production may be involved in disease pathogenesis.

Adult↗
PubMed1994

Enteroaggregative Escherichia coli: another cause of acute and chronic diarrhoea in England?

Enteroaggregative Escherichia coli (EAggEC) has been found to be associated with acute and persistent diarrhoea in children in developing countries. Its clinical significance in developed countries has not been examined in much detail. In a survey of faecal samples from children with diarrhoea presenting to a children's hospital in East London between August and December 1988, EAggEC strains were isolated in 8 of 297 (2.7%) consecutive stool samples collected from 289 children and in 5 of 34 typed E. coli isolates during 1988. Of the 13 children found to be excreting EAggEC, 8 had acute diarrhoea and 5 had chronic diarrhoea of more than 14 days' duration; 5 children had mixed infections. Compared to other organisms found during the same period, EAggEC were isolated as frequently as many other better-known pathogens such as enteropathogenic E. coli, Campylobacter, Salmonella, Shigella, Giardia lamblia, and Cryptosporidium. We conclude that EAggEC may be an important pathogen in developed countries.

Acute Disease↗
PubMed1993

Properties of Vero cytotoxin-producing Escherichia coli isolated from human and non-human sources.

Vero cytotoxin-producing Escherichia coli (VTEC) are an important cause of disease in man and animals. In addition to the production of VT these strains may possess other properties that are required for full virulence. Examples of some recent molecular studies are reviewed. Use of oligonucleotide probes and the polymerase chain reaction provide methods for the identification and typing of different VT genes. Several VTEC have the ability to cause attaching and effacing lesions of the epithelial microvilli. Hybridization experiments with the eae probe (E. coli attaching and effacing) showed homology with VTEC of human origin of eight different O serogroups. Properties of VTEC from human infections have been compared to strains isolated from animals and foods.

Animals↗
PubMed1993

Vero cytotoxin-producing Escherichia coli, particularly serogroup O 157, associated with human infections in the United Kingdom: 1989-91.

This survey reports the results of investigations performed by the Laboratory of Enteric Pathogens (LEP), to identify evidence of human infection with Vero cytotoxin-producing Escherichia coli (VTEC) in the UK during the period 1989-91. Bacterial isolates, faecal specimens and serum samples were received from patients suffering from diarrhoea, bloody diarrhoea and haemolytic uraemic syndrome. Using serotyping, Vero cytotoxin gene probing and an ELISA for serum antibodies to E. coli O 157, evidence of infection was detected in 232, 428 and 615 individuals in 1989, 1990 and 1991 respectively. Of these individuals, 15% were reported as having HUS. Vero cytotoxin-producing E. coli O 157 was the most frequently encountered serogroup, with isolations from a total of 1092 individuals over the 3-year period. The incidence of VTEC infection increased from 0.41/100,000 in 1989 to 1.07/100,000 in 1991. The area with the highest rate of infection in each year was Scotland, increasing from 1.37/100,000 in 1989 to 3.97/100,000 in 1991.

Adolescent↗
PubMed1993

Virulence properties of Escherichia coli strains belonging to serogroups O26, O55, O111 and O128 isolated in the United Kingdom in 1991 from patients with diarrhoea.

Some strains of Escherichia coli belonging to serogroups O26, O55, O111 or O128 produce Vero cytotoxin (VT). These serogroups are included in the range of enteropathogenic E. coli (EPEC) serogroups for which commercial antisera are available. In an attempt to obtain information on VT-producing strains other than those of serogroup O157, 122 strains belonging to these four serogroups and isolated in 1991 from patients with diarrhoea in the United Kingdom were tested for hybridization with VT probes. Only 18 of the 122 strains were VT-positive and these were O26 or O128. However 90 strains hybridized with the E. coli attaching and effacing (eae) probe (including 14 VT-positive strains) and 17 with the enteroaggregative E. coli (EAggEC) probe. For 78 eae-positive and 9 EAggEC-positive strains, tissue culture tests correlated with the probe results as the strains gave, respectively, either localized adhesion and a positive fluorescent-actin staining test or a characteristic aggregative attachment. A total of 111 of the 122 strains belonging to serogroups O26, O55, O111 or O128 possessed properties that may be associated with the ability to cause human diarrhoeal disease, and similar studies are needed on strains from the other classical EPEC serogroups.

Adult↗
PubMed1993

A longitudinal study of Vero cytotoxin producing Escherichia coli in cattle calves in Sri Lanka.

Two cohorts of 10 and 16 calves were followed at weekly or fortnightly intervals from 4-28 and 1-9 weeks respectively to determine whether natural infection by Vero cytotoxin (VT) producing Escherichia coli (VTEC) occurred. Ninety-one of 171 (53%) faecal specimens were VTEC positive and 20-80% of animals at any given time excreted VTEC. Of 104 VTEC strains studied further, 6 different serogroups (O 22.H16; O 25.H5; O 49.H-; O 86.H26; O 88.H25; O 153.H12) and an untypable strain (O? .H21) were identified. All strains belonging to the same serotype had identical profiles of reactivity with DNA probes to toxins VT1 or 2, LTI or II and a probe (CVD419) derived from a plasmid carried by enterohaemorrhagic Escherichia coli O 157.H7. Four of these serotypes were found in the faecal flora of the calves, taken as a group, throughout the 4-month study period. Sixty percent of the strains hybridized with the probe for VT1, 4% with the probe for VT2, and 36% with both probes. Faecal VTEC were significantly associated with overt diarrhoeal illness in animals < 10 weeks of age, but no characteristic profile of markers (serotype or hybridization pattern) in E. coli isolates was associated with diarrhoea. A serological response to VT1 was detected in some animals, but faecal VT1 VTEC excretion persisted in spite of seroconversion. VT1 seroconversion was not associated with diarrhoea. A serological response to VT2 was not detected even in those animals excreting VT2 VTEC in the faeces.

Animals↗
PubMed1993

Examination of raw beef products for the presence of Vero cytotoxin producing Escherichia coli, particularly those of serogroup O157.

Fifty-four of 310 (17%) samples of raw beef products contained Vero cytotoxin (VT)-producing Escherichia coli (VTEC) detected by DNA probes for the VT genes. VTEC strains examined in detail from a selection of the positive samples belonged to several O serogroups, some of which have been associated with human diarrhoea or haemolytic uraemic syndrome. Some of the strains possessed properties that may contribute to virulence in man. None of the food samples contained VT-producing E. coli O157 when tested by a combination of VT probe tests and colony immunoblotting with commercially available anti-O157 serum. Quantification of the immunoblotting technique indicated that O157 VTEC could be recovered from artificially-inoculated meat samples at a level of less than one organism per gram. Five of the food samples carried E. coli O157 strains that did not produce VT and differed in other properties from O157 VTEC.

Animals↗
PubMed1993

Use of digoxigenin-labelled oligonucleotide DNA probes for VT2 and VT2 human variant genes to differentiate Vero cytotoxin-producing Escherichia coli strains of serogroup O157.

Digoxigenin-labelled oligonucleotide DNA probes specific for B-subunit genes of Vero cytotoxin 2 (VT2) and a variant of VT2 (VT2vha) were used to differentiate 116 strains of Escherichia coli serogroup O157 belonging to phage types 1, 2, 4, 8, 14, and 49. Of these strains, 38% had sequences for both VT2 and VT2vha, 38% had sequences for VT2 only, and 24% had sequences for VT2vha only. Oligonucleotide probe hybridization subdivided strains of all of the phage types except phage type 1. The greatest variation in toxin gene pattern was observed with strains of phage type 14, for which there were six distinct patterns when the presence or absence of VT1 genes was also considered. Two strains from each phage type group were examined for bacteriophages encoding VT production. Two of the six VT2vha-producing strains carried phage from which DNA hybridized with the VT2vha-specific probe. Phages were not detected in the remaining four VT2vha strains, suggesting that genes may be chromosomally located or associated with a defective prophage. In contrast, seven of the eight VT2 strains carried phages from which DNA hybridized with the VT2-specific probe. Two strains of E32511 (O157:H-) were also investigated. One strain (E32511A) possessed gene sequences for both VT2 and VTvha and was shown to carry phage possessing gene sequences for VT2. With strain E32511B, however, phages were not detected and DNA hybridized only with the VT2vha probe. Analysis of total genomic DNA digested with restriction endonuclease EcoRI showed that polymorphisms were seen with VT2 strains and not with VT2vha strains.

Bacterial Toxins↗
PubMed1992

Vero cytotoxin-producing Escherichia coli O 157 in the United Kingdom.

A total of 226 cultures of Vero cytotoxin-producing Escherichia coli O 157 isolated from humans was received by the PHLS Laboratory of Enteric Pathogens during the six month period January to June 1992. A record monthly total of 122 isolates was received in June. Ten phage types (PT) were identified during this period; PT 2 (45%) and PT 49 (21%) predominated. In addition, 27 human sera with antibodies to E. coli O 157 lipopolysaccharide (LPS) were examined from other cases during this period, making a total of 253 cases of infection associated with E. coli O 157.

Bacterial Toxins↗
PubMed1992

Inflammatory cells and eicosanoid mediators in subjects with late asthmatic responses and increases in airway responsiveness.

To determine the relationship of inflammatory cells and eicosanoid mediators to the pathogenesis of the late asthmatic response (LAR) and increases in nonspecific airway responsiveness, we studied bronchoalveolar lavage (BAL) cells and fluid in 27 subjects 12 hours after inhaled antigen challenge. Methacholine challenge was performed before antigen challenge and 24 hours later (12 hours after BAL). Eight subjects had no LAR (-LAR, less than or equal to 10% fall in FEV1), nine subjects had an equivocal LAR (+/- LAR, 11% 25% fall in FEV1), and 10 subjects had a definite LAR (+LAR, greater than 25% fall in FEV1). Subjects developing +LAR had increased airway responsiveness at baseline compared with that of subjects developing an +/- LAR, but not with subjects having -LAR. If airway responsiveness was markedly increased at baseline, further increases after antigen challenge were often not observed. We found that both percent neutrophils and eosinophils increased in BAL as the severity of the LAR increased, but significant differences between the groups with -LAR and +LAR were only observed when both cell types were considered together. In addition, there was a significant correlation between the combined cell percentages and the severity of the LAR as determined by fall in FEV1. Likewise, increases in airway responsiveness were associated with significant increases in both neutrophil and eosinophil numbers, but only neutrophils correlated with the change in airway responsiveness after antigen challenge. However, despite the significant physiologic and cellular differences that we found between our groups, no significant differences could be found in BAL eicosanoid-mediator concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗
PubMed1992

Aerosolized antigen exposure without adjuvant causes increased IgE production and increased airway responsiveness in the mouse.

Inhalation of an antigen, ovalbumin (OVA), in the absence of adjuvant has been demonstrated to induce an immune response that is associated with increased airway responsiveness. Determination of OVA-specific serum IgE and IgG antibody responses revealed an early increase in antibody titers that were initially restricted to the IgE class. Subsequently, IgG antibody titers increased and IgE antibody plateaued. Furthermore, we observed a tenfold increase in the number of lymphocytes caused by a predominant expansion of CD3+ T cells in the peribronchial-associated lymph modes (PBLNs) of sensitized animals compared with the numbers of cells in control animals or in the gut-associated lymphoid tissue. The sensitized animals demonstrated an increase in airway responsiveness to intravenous methacholine challenge. Analysis of in vitro immunoglobulin production by spleen mononuclear cells revealed increased spontaneous IgE production that was more than fourfold enhanced in the presence of OVA, but IgG production was not increased. Spleen and PBLN lymphocytes, but not lymphocytes from gut-draining lymph nodes, demonstrated a proliferative response to OVA. Control animals exhibited no proliferative response to OVA. Histopathologic examination of the sensitized lung revealed an absence of acute inflammatory cells (e.g., neutrophils and macrophages), lymphocytes, or monocytes at the time of the increased airway hyperresponsiveness. These data indicate that, after sensitization of mice by inhalation of antigen, the animals develop a specific IgE antibody response, expansion of PBLN lymphocyte numbers, and increased airway hyperresponsiveness in the absence of signs of airway inflammation.

Adjuvants, Immunologic↗
PubMed1992

Properties of Vero cytotoxin-producing Escherichia coli of human origin of O serogroups other than O157.

The 48 Vero cytotoxin-producing Escherichia coli (VTEC) examined for properties associated with virulence were of human origin and represented 17 O serogroups other than O157 and O26. Only Vero cytotoxin production was common to all the strains. About 60% produced enterohemolysin and hybridized with the CVD419 probe derived from plasmid sequences of E. coli O157. Thirteen strains gave localized adherence (LA) to HEp-2 cells. All of these hybridized with the E. coli attaching and effacing (eae) gene probe and were positive in the fluorescence actin staining test, properties characteristic of strains that efface intestinal microvilli. A further 5 strains were eae probe-positive but did not give LA. None of the VTEC hybridized with a probe specific for the enteropathogenic E. coli adherence factor. Seven strains adhered to HEp-2 cells in a diffuse or aggregative pattern but did not hybridize with probes for these phenotypes. Non-O157 E. coli strains are diverse in their properties, although some may share virulence mechanisms with other diarrheogenic E. coli.

Animals↗
PubMed1992

Evaluation of a Salmonella-specific DNA probe by colony hybridization using non-isotopic and isotopic labeling.

A 2.3 kilobase (kb) Salmonella probe, JEO402-1, and two subfragments, F1214 (1.3 kb) and F1217 (0.8 kb), have been evaluated by colony hybridization using pure cultures of Salmonella serovars and non-salmonella bacteria. JEO402-1, and its subfragments, F1214 and F1217, hybridized to all of 156 different Salmonella serovars tested, while there was no reaction to 112 non-salmonella strains belonging to 19 genera and 37 species of Enterobacteriaceae. Together with previously published results, the JEO402-1 probe has now been shown to detect a total of 396 Salmonella strains belonging to 214 serovars of Salmonella subspecies I-VI. A total of 178 non-salmonella strains representing 23 genera and 51 species of Enterobacteriaceae have all tested negative with JEO402-1. The hybridization results obtained using a digoxigenin-labeled probe were similar to those obtained with 35S isotopic labeling when complete colony lysis was ensured.

Bacterial Typing Techniques↗
PubMed1992

Ability of enteroaggregative Escherichia coli strains to adhere in vitro to human intestinal mucosa.

A collection of 44 enteroaggregative Escherichia coli (EAggEC) strains isolated from infants with diarrhea in India and the United Kingdom were examined for their ability to adhere in vitro to human intestinal mucosa and by electron microscopy for production of putative adherence factors. None of the strains adhered to human duodenal mucosa, and six strains tested did not adhere to ileal mucosa; all 44 strains, however, adhered to human colonic mucosa in localized aggregates. Electron microscopy of infected colonic mucosa indicated fimbrially mediated adhesion of the EAggEC strains. Four morphologically distinct kinds of fimbriae, including a new morphological type of E. coli fimbriae consisting of bundles of fine filaments, were identified among the EAggEC strains; this new type of fimbria was observed in 43 of the 44 EAggEC strains. Forty-three of the 44 EAggEC strains were positive with a DNA probe developed to identify EAggEC, and most of the strains belonged to serotypes unrelated to the other major classes of diarrheic E. coli. These results suggest that EAggEC may be a large-bowel pathogen and colonize the colon by a fimbrially mediated adhesion mechanism.

Bacterial Adhesion↗
PubMed1992

The utility of spirometry in the diagnosis of reversible airways obstruction.

Patients with suspected reversible airways obstruction (RAO) sometimes report subjective benefit after bronchodilator treatment despite no objective spirometric improvement. One possible explanation for this is improvement in volume-related or plethysmographic parameters in the absence of spirometric improvement. One hundred patients with RAO were assessed before and after inhaled bronchodilator to determine the prevalence of improvement by plethysmographic parameters in the absence of improvement in spirometric parameters. Spirometry alone (FEV1, FVC, and FEF25-75%) identified reversibility of airflow limitation in 82 patients. Reversibility was identified by body plethysmography (specific conductance [SGaw], thoracic gas volume [TGV], and isovolume maximum expiratory flow rates [IVMEF]) in 15 of the remaining patients. The percent predicted FEF25-75% at baseline was higher in patients who required plethysmography to identify reversibility, but could not be used to predict the lack of a spirometric response for any individual patient. We conclude that spirometry alone fails to identify reversibility in approximately 15 percent of patients, and that most of these patients can be identified by additional plethysmographic measurements of volume-related parameters. At any one point in time, multiple tests must be used together to adequately identify the majority of patients with reversible airways obstruction. Improvement in volume-related parameters may explain why some patients with RAO improve subjectively with bronchodilators but show no spirometric improvement.

Adrenergic beta-Agonists↗