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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cellular uptake by human neutrophils and the intraphagocytic biological activity of the new macrolide antimicrobial agent dirithromycin (0.01-2 mg/L) compared with erythromycin was investigated in vitro. Staphylococcus aureus, Listeria monocytogenes and Legionella pneumophila were used as the test intracellular microbial pathogens. After coincubation (45 min at 37 degrees C) of neutrophils with a fixed concentration of 2 mg/L of each antibiotic the respective intracellular/extracellular ratios for erythromycin and dirithromycin were 6.1 +/- 2.5 and 10.6 +/- 2 respectively (P < 0.005). Using a combination of techniques (colony counting, radiometry and fluorescence microscopy) both erythromycin and dirithromycin at concentrations of 0.01 and 0.5 mg/L and higher, respectively, were found to possess dose-related intraphagocytic bacteristatic activity for each of the test microbial pathogens. The effects of dirithromycin and erythromycin (1-20 mg/L) on neutrophil chemotaxis and generation of reactive oxidants by these cells were also investigated in vitro. Both antimicrobial agents caused a dose-related stimulation of neutrophil migration which was associated with inhibition of leucoattractant-activated generation of superoxide and activity of the myeloperoxidase/H2O2/halide system. However, superoxide generation by neutrophils activited with opsonized zymosan or phorbol myristate acetate was unaffected by the macrolides. These findings demonstrate that dirithromycin accumulates in human neutrophils, is biologically active intracellularly and modulates leucoattractant-activated superoxide generation and chemotaxis.
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PMID:Investigation of the in-vitro uptake, intraphagocytic biological activity and effects on neutrophil superoxide generation of dirithromycin compared with erythromycin. 133 69

An enhanced chemiluminescence enzyme-linked immunosorbent assay has been developed for the detection of soluble antigen in the urine of patients with Legionnaires' disease (LD). In the assay antigen(s) in the urine samples are captured by a rabbit anti-L. pneumophila antibody coated onto microtitre strips. A fluorescein-isothiocyanate (FITC) conjugate of the same antibody is then added which binds to the captured antigen. Any immobilized FITC-labelled antibody is then detected with a horseradish peroxidase (HRP) conjugate of a monoclonal anti-FITC antibody. HRP activity is monitored after oxidation of luminol in the presence of H2O2 and iodophenol. The resulting luminescence is recorded using a camera luminometer. Urine specimens were available for testing from 31 patients with evidence of ongoing L. pneumophila serogroup 1 infection. A positive result was obtained in the cases of 12/12 specimens from culture-proven LD patients, and 16/19 specimens from patients with serological evidence of LD. Thus the sensitivity is estimated to be 28/31 (90%). The specificity was estimated using urine specimens from eight patients with non-L. pneumophila pneumonias of known aetiology. All eight specimens gave a negative result.
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PMID:Detection of Legionella pneumophila serogroup 1 urinary antigen using an enhanced chemiluminescence ELISA. 212 Sep 8

The outer membrane proteins of Legionella pneumophila serogroups 1 to 8 were prepared from broken cells by selective solubilization using sodium lauryl sarcosinate. The isolated proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose sheets. Rabbit antisera against each of the eight serogroups of L. pneumophila were obtained by immunizing each animal with live bacteria. The transferred proteins were revealed using these antisera and peroxidase-labeled swine anti-rabbit immunoglobulins. Antigenic determinants common to all eight serogroups were found in at least three outer membrane antigens (19, 29, and 45 kilodaltons (kDa)). However, cross-absorption experiments revealed that these three antigens were immunologically related, but not identical among serogroups. The antigenic relationships observed with two of these three antigens correlated well with cross-reactions observed in immunofluorescence. When a monoclonal antibody directed against L. pneumophila serogroup 1 lipopolysaccharide was used to reveal a blot of serogroup 1 outer membrane antigens, the 29- and 45-kDa bands appeared. This demonstrates a strong association between lipopolysaccharide and outer membrane proteins.
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PMID:Antigenic variability of the outer membrane antigens of Legionella pneumophila serogroups 1 to 8. 244 23

Legionella pneumophila was detected and identified by an immunoblot assay using a monoclonal antibody specific to serogroups 1 to 8. Samples containing L. pneumophila were plated on buffered charcoal yeast extract agar supplemented with glycine, vancomycin, and polymyxin B. After incubation at 35 degrees C for 3 days, colonies were transferred to nitrocellulose membranes by blotting. Simultaneous detection and identification of L. pneumophila were done by treating the membrane with the monoclonal antibody and a peroxidase conjugate to mouse immunoglobulins. A diffuse cross-reaction was observed with Pseudomonas fluorescens colonies, but this was a low-level reaction that could easily be differentiated from the strong specific reactions to L. pneumophila.
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PMID:Rapid detection and identification of Legionella pneumophila by a membrane immunoassay. 276 70

Four strains of Legionella pneumophila of different virulence as identified by ability to produce pneumonia and death in guinea-pigs infected by a fine-particle aerosol were examined for factors which may intracellularly influence virulence. Possible bactericidal mechanisms possessed by alveolar phagocytes were examined. A relationship could be established between resistance to H2O2, catalase activity and virulence amongst the strains. Virulent strains resisted the bactericidal activity generated by the xanthine oxidase system; avirulent strains did not. Incorporation of various specific inhibitors of the xanthine oxidase system indicated that the main bactericidal activities were associated with the production of H2O2 and hydroxyl radicals (.OH). All strains of L. pneumophila were susceptible to the bactericidal activity generated by the myeloperoxidase-H2O2-halide system, confirming earlier observations that polymorphonuclear neutrophil leucocytes (PMNLS) are able to kill both virulent and avirulent strains of L. pneumophila.
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PMID:The effect of oxygen-dependent antimicrobial systems on strains of Legionella pneumophila of different virulence. 301 84

Using immunocytochemical techniques at the light and electron microscope levels, Legionella pneumophila and one of its extracellular proteases were located in the lungs of guinea pigs with experimental Legionnaires' disease (LD). L. pneumophila was immunostained by several peroxidase- and gold-labelling methods for light and electron microscopy. The protease was immunolabelled in tissue fixed in Carnoy's fluid at the light microscopical level and on broth-grown organisms at the ultrastructural level. It was not labelled in either formalin- or glutaraldehyde-fixed tissue. Using double-labelling techniques, L. pneumophila and protease were located in the same section and were shown to be intimately associated with pulmonary lesions, providing strong evidence for the role of this protease in LD pneumonia.
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PMID:Immunocytochemical demonstration of the association between Legionella pneumophila, its tissue-destructive protease, and pulmonary lesions in experimental legionnaires' disease. 332 32

Legionellae are widely spread in natural and man-made habitats. In many instances contaminated tap water has been linked to sporadic or endemic cases of human pulmonary infections, but it is not known why, in spite of frequent occurrence, legionellae only rarely cause disease. Monoclonal antibodies against Legionella pneumophila serogroup 1 (Philadelphia 1) were prepared in order to distinguish between subtypes of this serogroup. Balb/c mice were immunized i.v. three times with heat inactivated bacteria. Antibody formation was detected by an enzyme-linked immunosorbent assay (ELISA) technique using peroxidase-conjugated antimouse IgG. Spleen cells were then fused with NS-1 myeloma cells and cloned by limiting dilution. Four monoclonal antibodies were studied in detail. The study included 47 strains of L. pneumophila: 19 strains were of human origin and 28 were isolated from different environmental sources. Most were from tap water, but none from natural habitats. All strains belonged to serogroup 1 as defined by direct immunofluorescence (DFA) using monospecific FITC-labelled polyclonal antisera from rabbits. The strains were further characterized by beta-lactamase production, activity of catalase, oxidase and proteases, analysis of ubiquinones, and demonstration of membrane protein patterns by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. A strong homogenicity between all the strains could be revealed by these methods independent of their origin. One of the monoclonal antibodies (B-1) was able to distinguish between human and environmental isolates. Eighteen of the 19 human strains reacted very strongly in DFA using antimouse immunoglobulin. No reaction, however, was seen with all of the environmental strains. Immunoblots were performed for characterization of the distinguishing feature using membrane complexes of all strains on nitrocellulose strips. The blots were incubated with antibody B-1, and immune complexes were detected by 125I-protein A. Broad intense blackening was seen between 22 and 70 kilodalton. This result suggests that no single protein, but rather a smaller component such as an oligosaccharide attached to constituents of different molecular weights, might be responsible for the discriminating reaction.
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PMID:Discrimination between clinical and environmental strains of Legionella pneumophila by a monoclonal antibody. 353 65

Legionella pneumophila was susceptible to the antimicrobial action of oxygen metabolites generated by both the myeloperoxidase-H(2)O(2)-halide and the xanthine oxidase systems.
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PMID:Effect of oxygen-dependent antimicrobial systems on Legionella pneumophila. 629 60

A simple combined peroxidase-catalase test has been developed which is applicable to live bacterial cells. Known strains of Legionella pneumophila were differentiated from other species of Legionella by being peroxidase positive and catalase negative.
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PMID:Whole-cell peroxidase test for identification of Legionella pneumophila. 636 66

We examined 40 strains of Legionella for reduced-oxygen scavenging enzymes. Using a simple reaction chamber with a Swinney filter for the Beers and Sizer assay, we determined the catalase activity of live cells grown on buffered charcoal-yeast extract agar. For 29 strains of Legionella pneumophila, the apparent first-order rate constants for catalase ranged from 0.000 to 0.005. Similarly, low values ranging from 0.001 to 0.005 were observed for Legionella wadsworthii, Legionella oakridgensis, and Legionella gormanii. High catalase activities were found for Legionella jordanis, Legionella longbeachae, Legionella micdadei, and Legionella bozemanii, with first-order rate constant values of 0.010 to 0.035. Cell-free extracts were analyzed for catalase, peroxidase, and superoxide dismutase. Cell-free extracts of all strains had superoxide dismutase levels ranging from 8.2 to 30.5 U per mg of protein. The species could be characterized by their catalase and peroxidase since L. pneumophila and L. gormanii had only peroxidase (relative molecular weight [Mr], 150,000); L. dumoffii had a peroxidase (Mr, 150,000) plus a catalase (Mr, 174,000); and all remaining species had catalase only (Mr, 300,000, 220,000, or 150,000).
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PMID:Determination of catalase, peroxidase, and superoxide dismutase within the genus Legionella. 649 Aug 28


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