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

The Legionnaires' disease (LD) bacterium appeared ultrastructurally identical in human lung, egg yolk membrane, and artificial media, seen as a blunt or tapering rod measuring 0.3 to 0.9 micron in diameter and greater than or equal to 2.0 micron long. Greatly elongated forms were commonly found in cultures and yold sac membranes after 5 to 7 days of growth but were only rarely seen in human lung. The LD bacterium was clearly prokaryotic. Prominent features included electron-lucent nucleoids interspersed among areas of well-defined ribosomes; cleanly circumscribed cytoplasmic vacuoles or granular inclusions; and a double envelope enclosure, each portion consisting of a triple-layered "unit" membrane, approximately 75 A wide. Division always occurred as a pinching, nonseptate process typical of bacteria with a double, gram-negative type of envelope. No definite structure was seen in the periplasmic space that might represent the peptidoglycan layer. These features of the LD bacterium confirm earlier reports of the gram-negative staining reaction of organisms obtained from cultures and preliminary evidence of their gram-negative ultrastructure. We found no unique features that would aid in the ultrastructural differentiation of the LD bacterium from other small gram-negative bacilli.
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PMID:Ultrastructure of the Legionnaires' disease bacterium. A study using transmission electron microscopy. 8 15

Two cases of Legionnaires' disease were diagnosed by direct isolation of the organism, from pleural fluid obtained before death in one case and lung tissue obtained after death in both cases. The organisms were recovered on a commercially prepared, enriched chocolate agar (Gibco, Madison, Wisconsin). Subcultures grew on commercially prepared, enriched chocolate agar (Baltimore Biological Laboratories, Cockeysville, Maryland) and on in-house enriched chocolate agar prepared with GC Medium Base (Difco, Detroit, Michigan). No growth was obtained on enriched chocolate agar prepared with trypticase soy agar. The organisms were poorly visualized in Gram-stained sections of formalin-fixed lung tissue. In Giemsa-stained sections poorly stained intracellular and extracellular slender rods were seen. However, with a silver impregnation stain, either a modified Dieterle or a modified Warthin-Starry procedure, many large, blunt-ended rods were seen. Smears prepared from minced formalin-fixed lung tissue and stained with a fluorescent antibody conjugate contained large numbers of well-stained organisms.
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PMID:Direct in-vitro isolation of the Legionnaires' disease bacterium in two fatal cases. Cultural and staining characteristics. 8 16

A gram-negative, weakly acid-fast bacillus has been isolated in embryonated eggs and in guineapigs from lung tissue of two renal-transplant recipients with acute purulent pneumonia. Culture of infected lung tissue and subculture of the egg isolate on artificial media, including media for legionnaires' disease bacterium (Legionella pneumophila), failed to produce growth. Ultrastructural analysis showed that the organism is a prokaryote with a cell-wall structure typical of a gram-negative bacillus but different from that of L. pneumophila. In both patients serum antibody to both isolates developed in high titre. In its microbiological, tinctorial, and ultrastructural characteristics this bacterium differs sufficiently from L. pneumophila and other pulmonary pathogens to indicate that it may be a new agent of bacterial pneumonia.
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PMID:New bacterial agent of pneumonia isolated from renal-transplant recipients. 8 63

Evidence obtained by others who used direct immunofluorescence staining to demonstrate serological differences among strains of Legionnaires disease bacterium prompted this study of parameters influencing the ability of the indirect immunofluorescence test to detect human antibodies to Legionnaires disease bacterium. A total of 25 Legionnaires disease bacterium strains, representing four serogroups, were used as immunofluorescence antigens to test selected human sera. The use of diethyl ether in preparing the antigens was discontinued when it was found that titers against ether-killed group 2 (Togus 1-like) antigens were impossible to determine. Instead, heat-killed suspensions of Legionnaires disease bacterium in 0.5% buffered normal chicken yolk sac were used to show the serogroup diversity of the strains and the serogroup specificity of the antibody response of some, but not all, patients with serological evidence of Legionnaires disease. These studies suggest that multiple antigens should be used in serological tests for Legionnaires disease. Furthermore, the fact that some sera contain antibodies that bind equally well to strains of all four serogroups implies that demonstration of a fourfold increase in titer of paired sera when tested with a single antigen should not be interpreted as evidence of infection with a strain of the same serogroup.
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PMID:Indirect immunofluorescence test for serodiagnosis of Legionnaires disease: evidence for serogroup diversity of Legionnaires disease bacterial antigens and for multiple specificity of human antibodies. 8 59

Culture of a bronchial aspirate from an immunosuppressed patient with severe pneumonia yielded a growth of filamentous poorly staining gram-negative rods. Fluorescence with Legionella pneumophila direct fluorescein-isothiocyanate conjugate was equivocal. Gas-liquid chromatography (GLC) and GLC/mass-spectrometry (GLC-MS) of the cellular fatty acids of the isolate confirmed that the organism was L. pneumophila. GLC and GLC-MS constitute a rapid and definitive method for identification of L. pneumophila isolates.
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PMID:Identification of a clinical isolate as Legionella pneumophila by gas chromatography and mass spectrometry of cellular fatty acids. 8 89

A group of related bacteria designated atypical Legionella-like organisms (ALLO) has been identified. ALLO, like L. pneumophila, are fastidious gram-negative rods that grow well on charcoal yeast extract (CYE) agar and produce ground glass colonies and browning of modified yeast extract agar. Unlike L. pneumophila, ALLO do not grow well on Feeley-Gorman (FG) agar, and on CYE agar they fluoresce under longwave ultraviolet light. ALLO and L. pneumophila have a similar predominance of branched-chain forms among total cellular fatty acids but have distinctive fatty-acid profiles. 2 patients with culture-verified ALLO pneumonia and 10 with pneumonia of uncertain aetiology who seroconverted to ALLO offer evidence that ALLO may be a cause of community-acquired pneumonia. Like L. pneumophila, ALLO appear to be water-associated; both persons with culture-verified ALLO infection were exposed to fresh water or its contents before becoming ill, and two strains of ALLO were isolated from water or wet environments.
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PMID:Atypical Legionella-like organisms: fastidious water-associated bacteria pathogenic for man. 9 Oct 24

A simple, relatively rapid silver impregnation stain has been found to stain Legionella pneumophila effectively in paraffin-embedded tissue sections while permitting visualization of histological detail. It may also be used to stain the organism in body fluids. The stain is not specific and thus must be confirmed by direct fluorescent-antibody technique or culture, but, in the absence of other bacilli demonstrable by Gram or other stain, visualization of typical bacillary forms in a patient with illness compatible with Legionnaires disease provides strong presumptive evidence supporting this diagnosis.
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PMID:Rapid presumptive bacteriological diagnosis of Legionnaires disease. 9 20

Human lung tissue containing the Legionnaires disease bacterium was fixed in seven different histological fixatives, processed, and embedded in paraffin. Deparaffined sections from each were stained by fluorescent antibody and by Dieterle silver impregnation. With the fluorescent antibody stain, the Legionnaires disease bacterium could be detected in tissues prepared with any of the fixatures, but the Dieterle silver impregnation was not satisfactory on Zenker-fixed tissues.
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PMID:Effect of various histological fixatives on fluorescent antibody detection of Legionnaires disease bacteria. 9 21

Eleven lung samples positive for Legionnaires' disease, 12 strains of Legionella pneumophila cultured on various bacteriological media, and one strain growth in the yolk sac of fertile hens' eggs were examined by negative staining, thin sectioning, and scanning electron microscopy. All organisms studied were ultrastructurally similar irrespective of strain, source, or method of cultivation, presenting mainly as short rods, 0.6 x 1.5 micrometer, with tapered ends, though long forms and filaments were also evident. In this they resembled typical Gram-negative organisms. Division was by non-septate binary fission, and the cell wall was composed of two triple-unit membranes with morphological evidence of a peptidoglycan layer. The bacterial cytoplasm was rich in ribosomes and nuclear elements and often contained vacuoles. No acid polysaccharides or bacterial appendages were detected surrounding the organisms. In lung tissue and yolk sac membranes, the organisms replicated within the cytoplasm of infected cells and in the intercellular spaces and were specifically identified in thin sections by immunoferritin techniques.
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PMID:Ultrastructure of Legionella pneumophila. 9 59

When the Legionnaires' disease (LD) bacterium is grown on supplemented Mueller-Hinton agar, brown pigmentation of the medium occurs. Since this browning may result from tyrosinase-mediated formation of melanin, we supplemented yeast-extract agar with various aromatic precursors of melanin and inoculated it with eight strains of the LD bacterium. Browning occurred with growth of each LD strain of the bacterium on yeast-extract agar enriched with 2.5 mmol/L of L-phenylalanine or L-tyrosine but not without such enrichment. Equimolar D-phenylalanine or D-tryosine in yeast-extract agar did not enhance browning. The LD bacterium may possess L-phenylalanine hydroxylase activity, but it does not use D-aromatic amino acids effectively in pigment production.
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PMID:Aromatic substrate specificity of browning by cultures of the Legionnaires' disease bacterium. 10 39


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