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A Ljungh

Publications and source records attributed to A Ljungh.

At least 145 records · Page 8Linked to original sources
PubMed1985

High surface hydrophobicity of autoaggregating Staphylococcus aureus strains isolated from human infections studied with the salt aggregation test.

A total of 209 strains of Staphylococcus aureus isolated from infections and 23 strains from nose cultures of healthy laboratory personnel were compared for relative surface hydrophobicity in the salt aggregation test (Lindahl et al., Biochim. Biophys. Acta 677:471-476, 1981). In the standard method, bacterial cell suspensions from blood agar-grown cultures were tested for visible aggregation by "salting out" in serial dilutions of ammonium sulfate (0.1 to 1.6 M [final concentration]). Bacteria were defined as extremely hydrophobic when showing autoaggregation in saline or in 0.002 M sodium phosphate buffer (pH 6.8). Using this definition, we found a large number of strains isolated from various infections to be very hydrophobic: 123 of 135 strains from patients with septicemia (91%), 54 of 60 strains from wound infections (90%), and 12 of 14 strains from urinary tract infections (86%). In contrast, only 9 of 23 strains from nose cultures of healthy carriers (39%) were autoaggregating. A total of 12 autoaggregating strains were grown on various solid and liquid media. Only growth on hematin agar was found to completely suppress surface hydrophobicity as revealed by our salt aggregation test method, and growth in liquid media prevented the expression of hydrophobicity in most strains. Growth at 20 or 42 degrees C or under anaerobic conditions did not affect hydrophobicity. Cells harvested from various phases of growth did not differ significantly in surface hydrophobicity. Heating washed cell suspensions at 56 degrees C did not affect the salt aggregation test values, whereas heating the cell suspensions at 80 and 100 degrees C caused a significant decline in hydrophobicity. The addition of ethylene glycol (25% [vol/vol] final concentration) prevented the autoaggregation of 10 of the 12 strains. Likewise, treating the cell suspensions with proteolytic enzymes decreased the surface hydrophobicity, indicating that surface proteins contribute to high surface hydrophobicity of autoaggregating strains.

Adolescent↗
PubMed1984

Asymptomatic urinary tract infection caused by Shigella sonnei.

The first case of asymptomatic urinary tract infection caused by Shigella sonnei in a patient, a 74-yr-old man, who was not a faecal carrier and had no history of dysentery is reported. Treatment with pivmecillinam 400 mg 3 times daily for 14 days was instituted and the bacteria were eradicated. The time and source of infection is unknown.

Aged↗
PubMed1983

Autoaggregating Yersinia enterocolitica express surface fimbriae with high surface hydrophobicity.

For 13 strains of Yersinia enterocolitica, there was a good correlation between the production of the broad-spectrum, mannose-resistant Yersinia haemagglutinin (MR/Y HA), the presence of fimbriae and high surface hydrophobicity. Each of these characters was expressed in cultures grown at low (less than 32 degrees C) but not at high (Greater than 35 degrees C) temperatures.

Fimbriae, Bacterial↗
PubMed1983

Binding of fibronectin to Staphylococcus strains.

Fibronectin, a major protein component of plasma and loose connective tissue has previously been shown to bind to several strains of Staphylococcus aureus. We examined a large number of strains of different species of Staphylococcus with respect to their ability to bind fibronectin. The relative numbers of strains defined as fibronectin-binders among the different species were as follows: S. aureus (22 of 23), S. haemolyticus (5 of 5), S. warneri (8 of 11), S. hyicus (5 of 6), S. hominis (13 of 17), S. saprophyticus (11 of 20), S. epidermidis (4 of 7), and S. simulans (8 of 10). Only three species showed a predominance of nonbinders over binders: S. capitis (4 of 14), S. xylosus (0 of 4), and S. cohnii (3 of 11). These data indicate that staphylococcal species isolated from soft tissue infections frequently have the ability to bind fibronectin and suggest that the ability to bind to this protein may contribute to the virulence of coagulase-positive and coagulase-negative staphylococci.

Fibronectins↗
PubMed1982

Binding of fibronectin to the surface of group A, C, and G streptococci isolated from human infections.

Sixty-nine haemolytic and non-haemolytic streptococcal strains were isolated from various human infections and serogrouped with the coagglutination test. The amount of 125I-fibronectin bound to bacterial cells in a standard assay was determined. Most of the group A, C, and G strains were able to bind fibronectin. None of the group B or D strains bound significant amounts of fibronectin. Group A, C, and G streptococci appear to preferentially bind the N-terminal region of the fibronectin molecule because the 25K N-terminal fragment of the protein could effectively inhibit the binding of 125I-fibronectin to cells. Furthermore, the ability of representative strains of group A, C, and G to bind fibronectin was markedly reduced after trypsin treatment of the cells. Fibronectin binding components released from one strain by trypsin treatment inhibited the binding of 125I-fibronectin to all group A, C, and G streptococci strains. These findings indicate similarities among fibronectin binding proteins of the three groups of streptococci tested. However, the relative susceptibility to trypsin of fibronectin receptors of the three strains differed as did the relative potency of the inhibitory activity of receptors solubilized from different strains. Binding of fibronectin to the cell surface of group A, C, and G streptococci may contribute to virulence, for instance by promoting specific attachment to exposed fibronectin in open wounds and tissue lesions.

Fibronectins↗
PubMed1982

Salt aggregation test for measuring cell surface hydrophobicity of urinary Escherichia coli.

The recently developed salt aggregation test for measuring relative surface hydrophobicity of bacteria was used to study Escherichia coli strains isolated from urinary tract infections. Of the 232 strains tested 166 (71.5%) aggregated in salt solutions of varying molarity (0.1-1.6 M final concentration). Mannose-resistant haemagglutination of various erythrocyte species and/or mannose-sensitive haemagglutination of guinea-pig erythrocytes was seen in 144 of the 166 salt aggregating strains. Two salt aggregation-negative (hydrophilic) strains exhibited mannose-sensitive haemagglutination. Fimbriae of varying morphology were seen in salt aggregating strains. Strains with type 1 fimbriae only generally showed lower surface hydrophobicity than strains exhibiting mannose-resistant haemagglutination. Growing strains at 18 degrees C suppressed fimbriation with a concomitant decrease in surface hydrophobicity and haemagglutination. The salt aggregation test proved to be a rapid and reproducible screening test for detecting bacteria with high surface hydrophobicity due to surface protein of fimbrial (haemagglutinating or non-haemagglunating) and non-fimbrial nature.

Adolescent↗
PubMed1982

Aeromonas hydrophila toxins - intestinal fluid accumulation and mucosal injury in animal models.

Strains of Aeromonas hydrophila were earlier shown to produce a heat-labile enterotoxin and two cytolytic toxins, alpha- and beta-haemolysin. These investigations have been extended. When separated from the cytolysins, the enterotoxin elicited fluid accumulation in rabbit intestinal loops. The electrolyte and albumin content of the fluid was similar to that of cholera toxin. The enterotoxin was non-injurious to the mucosa. Purified hemolysins did not give a positive loop test. They produced hemorrhagic enteritis with leakage of small amounts of hemorrhagic fluid. In electrolyte and albumin content this fluid differed from the fluid elicited by the enterotoxin. Prostaglandin inhibitors did not reduce the diarrheal response to Aeromonas enterotoxin. The cAMP inhibitor chlorpromazine reduced the fluid accumulation in rat and mice intestinal loops by 60%. Cholera toxin and Aeromonas enterotoxin may have a common pathway in the elicitation of intestinal fluid accumulation. By passage in intestinal loops, strains of A. hydrophila could regain lost enterotoxicity. Experimental diarrhea could not be induced in rabbits and rats with various enterotoxigenic strains of Aeromonas.

Aeromonas↗
PubMed1982

Cytotonic enterotoxin from Aeromonas hydrophila.

Aeromonas hydrophila produces two hemolysins and an enterotoxin during growth. Enterotoxin, separated from the hemolysins, gave positive reactions in the rabbit intestinal loop test, the rabbit skin test and the adrenal Y1 cell test. Neutralization experiments in the rabbit loop, rabbit skin and Y1 cell tests failed to demonstrate any immunological relationship between Aeromonas enterotoxin and cholera toxin or Escherichia coli heat-labile enterotoxin. Prior incubation of Aeromonas enterotoxin with gangliosides did not inhibit the positive test results in these systems. A co-agglutination test with antiserum to purified cholera toxin was negative for Aeromonas enterotoxin, which therefore seems to be immunologically distinct from cholera toxin. The Aeromonas enterotoxin induced steroid secretion in adrenal Y1 cells and increased the intracellular cyclic adenosine monophosphate (cAMP) content of Y1 cells as well as of rabbit intestinal epithelial cells. It thus seems to act via the adenylate cyclase-cAMP pathway and should be classified as a cytotonic enterotoxin according to the classification of Keusch and Donta (1975).

Adenylyl Cyclases↗
PubMed1982

Two membrane damaging toxins from Aeromonas hydrophila.

The effects of two hemolysins (alpha and beta) from Aeromonas hydrophila on human lung fibroblasts were investigated. The toxins differed with respect to relative size of lesions induced in the plasma membrane, morphological effects, reversibility of effects and adsorption to fibroblasts. The effect of alpha-hemolysin appears to be restricted to the plasma membrane level, whereas the beta-hemolysin is strongly cytotoxic and probably acts on some intracellular target in addition to the primary target, the plasma membrane.

Aeromonas↗
PubMed1981

Aeromonas toxins.

Explore the source record for details and available documents.

Aeromonas↗
PubMed1981

Separation and characterization of enterotoxin and two haemolysins from Aeromonas hydrophila.

Aeromonas hydrophila produces two haemolysins, now designated alpha- and beta-haemolysin (formerly aerolysin or cytotoxic protein), and one enterotoxin. These toxins were separated and purified by isoelectric focusing and gel chromatography. Alpha- and beta-haemolysin differ with regard to prerequisites for their elaboration, such as selection of A. hydrophila strains and temperature and time for cultivation. The nature of their lytic effects on erythrocytes and toxic effects on tissue culture cells differs significantly. Alpha- but not beta-haemolysin was inactivated by reducing agents and activated by oxygen, while beta-haemolysin was more resistant than alpha-haemolysin to proteolytic enzymes but was inactivated by crude gangliosides. When separated from the two haemolysins, the enterotoxin gave positive reactions in the rabbit intestinal loop test, the rabbit skin and the adrenal Y1 cell test, though the sensitivity of the Y1 cell was low as compared with cholera toxin and E. coli LT toxin. No cytotoxic effects were obtained in HeLa cells.

Aeromonas↗
PubMed1981

Membrane-damaging and cytotoxic effects on human fibroblasts of alpha- and beta-hemolysins from Aeromonas hydrophila.

The effects of two hemolysins (alpha and beta) from Aeromonas hydrophila on human lung fibroblasts were investigated. The toxins differed distinctly in regard to the morphological changes they produced. The alpha-hemolysin caused rounding of the cells. The beta-hemolysin caused a striking vacuolization of the cytoplasm in cells which remained spread out on the growth surface. The toxins also differed as to relative size of the initial lesions they induced in the fibroblast membrane, scored by leakage of different-sized cytoplasmic markers. The alpha-hemolysin induced larger lesions than did the beta-hemolysin. It was indirectly demonstrated that the alpha-hemolysin did not bind, or bound only transiently, to the fibroblasts. By contrast, the beta-hemolysin bound rapidly and firmly. The cytopathogenic response to the alpha-hemolysin was reversible, whereas cells treated with small amounts of the beta-hemolysin for only 1 min invariably died within a few hours. Thus, the two hemolysins from A. hydrophila, despite many biochemical similarities, show essential dissimilarities in their interactions with cultured cells.

Aeromonas↗
PubMed1980

Evaluation of a test kit (Oxi/Ferm system) for identification of oxidase positive gram negative neoenteropathogenic bacteria.

During recent years a number of oxidase positive gram negative bacteria have been implicated as causative agents of outbreaks of acute diarrhoeal disease and food-poisoning in many parts of the world. As taxonomic positions of many of them are not yet well-defined, their identification is often difficult and time consuming. This Oxi/Ferm tube system was evaluated in relation to the conventional battery of tests with 128 organisms isolated from different sources in various parts of the world. About 72% of them, comprising strains of 6 species, could be identified in this system at the species level. The Group "F" vibrios were identified as Aeromonas hydrophila in the Oxi/Ferm system. A few additional tests in the kit is are recommended to facilitate accurate identification of various species including group F vibrios. The convenient Oxi/Ferm tube system will then be very useful for the medical, veterinary, fishery, water and industrial microbiologists for rapid and easy identification of these microorganisms which are of importance to all of them, as opposed to the conventional test system.

Animals↗