PubMed Health⌕ Search

Biomedical subjects

O Olsvik

Publications and source records attributed to O Olsvik.

At least 73 records · Page 4Linked to original sources
PubMed1989

Enteropathogenic Escherichia coli serotype O111:HNT isolated from preterm neonates in Nairobi, Kenya.

This investigation was initiated as a consequence of several cases of diarrhea in a nursery ward for preterm babies in Nairobi, Kenya. Ten lactose-positive colonies were isolated from the stools of each of 30 neonates, regardless of whether they had diarrhea; 229 strains were identified as Escherichia coli and 65 strains were identified as Klebsiella pneumoniae. Six strains were lost during laboratory handling. No other bacterial, viral, or parasitic enteropathogens were identified. Using synthetic alkaline phosphatase-labeled probes, the bacterial isolates were found to be negative for the presence of genes coding for heat-stable and heat-labile enterotoxins. Seventy-eight E. coli strains isolated from a total of 13 neonates possessed the E. coli enteropathogenic adhesion factor (EAF) gene, as demonstrated by the use of a cloned radiolabeled DNA fragment probe. These strains possessed similar plasmid profiles constituting a core plasmid profile, and while all adhered to HeLa cells, none produced Vero cell cytotoxins. The EAF gene was located on a 65-megadalton plasmid. Serotyping showed the strains to be of serogroup O111 and serotype H nontypable, a well known enteropathogenic type. Five neonates died during the outbreak, and the fatality rate was 30.7% (4 of 13) for neonates infected with EAF-positive E. coli strains compared with 7.7% (1 of 13) for neonates from whom only EAF-negative E. coli strains were isolated. K. pneumoniae only was isolated from five neonates.

Adhesins, Escherichia coli↗
PubMed1988

Heat-stable-enterotoxin-producing Escherichia coli strains isolated from dogs.

Five strains of hemolytic Escherichia coli isolated from dogs suffering from diarrhea were shown by radioactive and enzyme-labeled oligonucleotide probes to possess genes coding for heat-stable enterotoxin (STIa). Four of the strains were shown by immunoassay (enzyme-linked immunosorbent assay) and bioassay (infant mouse test) to produce STI in vitro. All five strains, however, were able to induce fluid accumulation in ligated dog intestinal loops. The four STI-producing strains all possessed the K99 fimbrial antigen (F5) and belonged to serotype O42:H37. In these strains, genes encoding STI were located on a 98-megadalton plasmid. In the fifth strain, which produced STI in vitro only after several subcultivations, the STI gene was located on an 80-megadalton plasmid. This strain was nontypable.

Animals↗
PubMed1988

Plasmids in Vibrio salmonicida isolated from salmonids with hemorrhagic syndrome (Hitra disease).

Vibrio-like isolates from Atlantic salmon (Salmo salar Linnaeas) and a few from rainbow trout (S. gairdneri Richardson) suffering from hemorrhagic syndrome (Hitra disease), also called cold-water vibriosis, a disease of great importance in Norwegian fish farming, were examined for plasmid content. Of 84 strains isolated from 1982 to 1984, 70 (83.3%) had a common 21-megadalton (MDa) plasmid. A 3.4-MDa plasmid was found in 58 of the strains with the 21-MDa plasmid, and a 2.8-MDa plasmid was found in 23 of the strains with both the 21- and 3.4-MDa plasmids. The strains were isolated from fish farms along the western and northern coasts of Norway. Ten (11.9%) of the strains possessed a 61-MDa plasmid in addition to a 21-MDa plasmid. Two strains had only a 21-MDa plasmid. Of the 84-Vibrio-like isolates, 14 did not harbor plasmids identical in mass to any other plasmids found in this material. Vibrio salmonicida strains, 257 in all, isolated from salmonids with the same disease from the same area from July 1986 to July 1987, all possessed a 21-MDa plasmid, either alone or in addition to a 3.4-MDa plasmid, or a combination of 3.4- and 2.8-MDa plasmids. Six of the strains had a 5.5-MDa plasmid instead of the 3.4-MDa plasmid. The restriction endonuclease patterns of the plasmids of similar molecular mass reflected similar nucleotide sequences. The plasmid content detected in isolates of V. salmonicida obtained from a coastline of more than 2,000 km and over a period of almost 6 years is stable.

Animals↗
PubMed1987

Production and characterization of monoclonal antibodies to toxic shock syndrome toxin 1 and use of a monoclonal antibody in a rapid, one-step enzyme-linked immunosorbent assay for detection of picogram quantities of toxic shock syndrome toxin 1.

Twenty-six hybridoma cell lines that produced monoclonal antibodies to toxic shock syndrome toxin 1 (TSST-1) were generated by immunizing mice with a highly purified preparation of TSST-1 and fusing their splenic lymphocytes with SP2/0-Ag-14 cells. One monoclonal antibody of the immunoglobulin G1 isotype, designated as PEC-1 10-2SCH, was selected for extensive study. The specificity of this antibody was determined by testing spent culture fluid filtrates of TSST-1- and non-TSST-1-producing strains of Staphylococcus aureus by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and enzyme-linked immunoelectrotransfer blot techniques. Monoclonal antibody PEC-1-10-2SCH was specific for TSST-1-producing strains of S. aureus, reacting with TSST-1 and two other proteins which appear to be unique to S. aureus strains that produce TSST-1. Monoclonal antibody PEC-1-10-2SCH was used in conjunction with polyclonal rabbit antibodies to TSST-1 in a rapid, one-step, sensitive, specific, and quantitative enzyme-linked immunosorbent assay. This assay was shown to be more sensitive, faster, and simpler to perform than previously described isoelectric focusing, immunodiffusion, and solid-phase radioimmunoassays for TSST-1. Monoclonal antibody PEC-1-10-2SCH was not reactive with Staphylococcus protein A under the conditions of the test.

Antibodies, Monoclonal↗
PubMed1985

Plasmid characterization of Salmonella typhimurium transmitted from animals to humans.

The transmission of pathogenic bacteria from animals to humans is widely studied because of its public health importance. In this study, we show the transmission of Salmonella typhimurium from cattle which had received no growth-promoting antibiotics to humans who had direct contact with the ill animals. On one cattle farm, the veterinarian attending the sick animals became ill, and two other individuals living on the farm later developed salmonellosis. The strains isolated from both humans and animals at one farm were identical as to antibiotic susceptibility and phage type, and they were specifically traced by the presence of a common 24-megadalton plasmid. Restriction enzyme digests of this plasmid from both human and animal strains were identical. At another farm, tetracycline-resistant S. typhimurium strains possessing a different profile (eight plasmids) were isolated from both animals and humans. The tetracycline-resistant clone was also isolated from animals at a third farm, but with animals and humans having no known contact with those of the other two farms.

Animals↗
PubMed1985

Characterization of enterotoxigenic Escherichia coli. Serotypes, enterotoxins, adhesion fimbriae, and the presence of plasmids.

Enterotoxigenic Escherichia coli of human and procine origin were characterized with respect to their O and H antigens, fimbrial antigens, and type of enterotoxin produced. Enterotoxin production was determined by bioassay (infant mice) and enzyme-linked immunoassay (ELISA). The presence of genes coding for the enterotoxins was determined by DNA-DNA hybridization. The number and molecular size of plasmids in the enterotoxigenic strains were determined by gel electrophoresis. Strains with the same serological pattern showed different plasmid profiles and could thereby easily be separated. One strain of porcine origin possessed only one plasmid, but produced both heat-labile enterotoxin and the F4 antigen (formerly K88), which is an unusual combination.

Animals↗
PubMed1983

Legionella extracellular protease activity on chromogenic peptides: a simplified procedure for biochemical enzyme identification.

Legionella strains produce extracellular proteases. One method to demonstrate these is through the activity of broth culture filtrates on para-nitroanilide (pNA)-derivatized peptides. Previously, this method has comprised a 100-times concentration of the filtrates, in order to bring the protease activity, as measured by the liberation of free pNA from hydrolysed peptides, up to easily recordable values. By introducing a diazotation step, the sensitivity of the test has been increased sufficiently to omit the time-consuming concentration procedure. Accordingly, the analysis of extracellular Legionella proteases by pNA-derivatized peptides has become rapid and straight-forward.

Chromogenic Compounds↗
PubMed1983

Patterns of extracellular proline-specific endopeptidases in Legionella and Flavobacterium spp. demonstrated by use of chromogenic peptides.

Some Legionella strains possess a strong extracellular proline-specific endopeptidase (PSE) activity. Using an enlarged selection of chromogenic peptides representing a variety of N-terminal amino-acids binding to a -prolyl-proline, paranitroanilide chain, PSE activity of Legionella and Flavobacterium strains was examined. Differences in PSE activity emphasized the importance of the chemical structure at the nonchromogenic end of the peptide substrates. There seem to be distinct patterns of N-terminal specificity of PSE in the two bacterial groups.

Chromogenic Compounds↗
PubMed1983

Differences in bindings to the GM1 receptor by heat-labile enterotoxin of human and porcine Escherichia coli strains.

Heat-labile enterotoxin producing strains of Escherichia coli were isolated from diarrheal faeces of humans and from the jejunum of pigs which had died of diarrhea. The heat-labile enterotoxin was assayed by three different enzyme-linked immunosorbent assays (ELISA). The first assay was based upon immunological cross-reactions between the heat-labile enterotoxins of E coli and Vibrio cholerae, the second on specific E coli heat-labile enterotoxin antibodies and the third on affinity of the toxin to the presumed cell membrane receptor, the ganglioside GM1. The heat-labile enterotoxins of human and porcine origin bound equally well to the same extent in the ELISA procedure, which utilized immunological cross-reactivity between the heat-labile enterotoxins of E coli and V cholerae. The reactivity, however, was quite different in the GM1-ELISA. The binding affinity was high between GM1 and enterotoxin produced by E coli strains of human origin, whereas the binding affinity was low for enterotoxin from porcine strains.

Animals↗
PubMed1982

Chlorpromazine inhibition of enterotoxin-induced fluid secretion and cAMP production in rat ileum.

A heat-labile enterotoxin prepared from E. coli (EcLT) increased fluid secretion and cAMP production by segments of rat ileum in vivo and in vitro. The effect of this toxin was compared to that of cholera toxin (VcLT). The increase of cAMP occurred more rapidly after EcLT than after VcLT indicating a difference in the kinetics of uptake or action of the two toxins. Chlorpromazine (CPZ) 5 mg/kg given by intramuscular injection 1 h before application of the toxins inhibited the increase in cAMP levels and the increase in fluid secretion in vivo. CPZ 10(-4) M given together with the toxins to intestinal loops in vitro inhibited the increase in cAMP levels and fluid secretion by this preparation. Scanning electron microscopy revealed that CPZ caused extensive shedding of the fluid-producing mucosal cells.

Animals↗
PubMed1982

Production of enterotoxin by Escherichia coli at four, twenty-two and thirty-seven degrees centigrade.

One hundred and seventy-seven Escherichia coli strains isolated from food, pigs and humans were tested for the production of heat-labile and heat-stable enterotoxin at 4, 22, and 37 degrees C. Heat-labile enterotoxin was detected in culture supernatants by an enzyme-linked immunosorbent assay, and heat-stable enterotoxin by the infant mouse bioassay. Thirty strains produced heat-labile enterotoxin, and twenty heat-stable enterotoxin. None of the strains isolated from food were enterotoxigenic. Fifty-seven per cent of the human and porcine strains producing heat-labile enterotoxin at 37 degrees C also produced the toxin at 4 degrees C. The fact that Escherichia coli enterotoxin may be present in food at consumption must be considered pathogenetically relevant.

Animals↗
PubMed1982

Demonstration of extracellular proteolytic enzymes from Legionella species strains by using synthetic chromogenic peptide substrates.

Crude concentrates of extracellular proteases from strains belonging to species within the genus Legionella were examined for their effect upon synthetic chromogenic tri- and tetrapeptides. For the species L. pneumophila, similar and reproducible substrate degradation patterns were found. Strains from the other Legionella species produced proteases with dissimilar proteolytic patterns, which were all distinct from those of the L. pneumophila proteases.

Chromogenic Compounds↗
PubMed1982

A heat-labile necrotic activity in supernatants from cultures of Legionella pneumophila.

Crude, concentrated extra-cellular supernatants from Legionella pneumophila produced a soft-tissue necrosis, demonstrated by intraperitoneal or sub-cutaneous injections into infant mice. The reaction was rapid and gave a hemorrhagic tissue necrosis within minutes. Being heat-labile, this tissue reaction is different from those of a heat-stable cytotoxin and a heat-stable hemolysin previously described.

Animals↗
PubMed1982

Demonstration of Escherichia coli heat-labile enterotoxin using bacterial cell sonicates.

Agar-plate colonies of Escherichia coli were suspended in 0.5 ml distilled water and sonicated for 15 s. The sonicate was tested for E. coli heat-labile enterotoxin by an enzyme-linked immunosorbent assay (ELISA). Sonication of enterotoxin-producing E. coli cells gave detectable toxin concentrations, which correlated well with the results obtained using culture broth supernatants for toxin detection in the ELISA. By using sonicates of isolated bacterial colonies from primary isolation agar plates, the subcultivation on agar plates or in culture broth tubes can be omitted. This may reduce the possibility of losing the plasmids coding for enterotoxin production. The time needed for analysis of suspected toxin producing E. coli strains will be reduced accordingly. Suspensions with bacterial counts of 10(6) per ml or more of E. coli, gave detectable levels of heat-labile enterotoxin in the sonicates.

Bacterial Toxins↗