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

Legionnaires' disease bacterium in tissue does not readily react with the Gram stain but can be seen by other stains and direct immunofluorescence. It is a slow-growing, aerobic, gram-negative rod that can be cultivated over a narrow temperature range on Mueller-Hinton agar supplemented either with complex biological mixtures or certain ferric salts and cysteine. The bacterium produces unique, branched-chain fatty acids, catalase, oxidase (weakly), and gelatinase and uses starch while ignoring other carbohydrates. Pigment production is related to tyrosine in the medium. In-vitro studies suggest susceptibility to all antibiotics except vancomycin, but a class 1 beta-lactamase has been demonstrated. Analysis of DNA confirmed the unrelatedness of this bacterium to previously recognized prokaryotes. Diagnosis of the disease has depended largely on serologic test findings and the demonstration of the bacterium in tissue and, occasionally, on isolation. Additional, simpler, and more rapid diagnostic tests should soon be available.
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PMID:Microbiology of Legionnaires' disease bacterium. 8 12

Legionella pneumophila (Lp) grow in cultures in human, guinea pig, and mouse macrophages from A/J strain mice. Because exudate macrophages from this strain of mice have been reported deficient in responsiveness to lymphokines, we thought it of interest to document the extent of responsiveness to interferon-gamma in the context of growth restriction of Lp. Peritoneal exudate macrophages were obtained from A/J mice and cultured in either the presence or absence of recombinant interferon-gamma. These cultures were then infected with Lp and the extent of bacterial growth estimated 48 hr later by means of a colony-forming unit (CFU) assay and electron microscopy. Interferon-gamma treatment significantly restricted the number of CFUs in the culture at concentrations as low as 20 U/ml, but did not affect the uptake of bacteria by macrophages. Furthermore, treatment with interferon induced morphological changes consistent with activated macrophages. The involvement of oxygen-dependent mechanisms in phagocyte killing and growth restriction was examined by the use of inhibitors such as superoxide dismutase (SOD) and catalase. Neither one of these inhibitors of toxic oxygen metabolites affected the interferon-gamma-induced suppression of Lp growth. These results suggest that although thioglycolate-induced exudate macrophages from A/J mice support the growth of Lp, these cells readily respond to the activating influence of interferon-gamma. Furthermore, lymphokine treatment does not inhibit Lp uptake by macrophages and apparently restricts the growth of bacteria by mechanisms independent of the activity of toxic oxygen metabolites.
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PMID:Interferon-gamma induced resistance to Legionella pneumophila in susceptible A/J mouse macrophages. 189 14

A novel bacterium, Protomonas extorquens was isolated from sputum, pleural effusion and ascitis in four cases of pulmonary infection by buffered charcoal yeast extract agar (B-CYE) which was generally used for Legionella spp. Three cases were so-called immunocompromised hosts (2 malignant diseases, 1 renal failure), and they died from underlying diseases. Protomonas extorquens was newly named by Komagata in 1984, which was characterized by production of pink pigment, growth in methanol medium and positive production of oxidase and catalase. This organism is ordinarily isolated from soil and dead leaves. This is the first report for isolation of P. extorquens from clinical specimens in Japan and it seems to have a significant role in immunocompromised hosts.
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PMID:[Clinical and bacteriological studies in four cases of pulmonary infection caused by Protomonas extorquens]. 221 63

A total of 163 strains, including 106 strains of Legionella pneumophila, 28 strains of Tatlockia micdadei, and 29 strains of other legionellae (including members of the proposed genus Fluoribacter), were studied. Ten tests which together could distinguish the genera previously proposed were identified. These tests included catalase-peroxidase, gelatinase, hippurate hydrolysis, starch hydrolysis, medium browning, acetoin production, oxidase, medium fluorescence, colony fluorescence, and the bromcresol purple spot test. T. micdadei strains were strongly catalase positive and bromcresol purple spot test positive and produced acetoin but otherwise were usually inert in the other tests. L. pneumophila and Fluoribacter species could usually be distinguished by strength of catalase activity, blue-white colony fluorescence (if present), and differences in frequency of hippurate hydrolysis, starch hydrolysis, yellow-green medium fluorescence, and, to a lesser extent, oxidase activity. With a simple algorithm and computer program, the overall accuracy was 98.8%.
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PMID:Application of numerical systematics to the phenotypic differentiation of legionellae. 255 May 14

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

We examined the ability of two recombinant human cytokines, granulocyte-macrophage colony-stimulating factor (rHu-GM-CSF) and interferon-gamma (rHu-IFN-gamma) to activate antibacterial mechanisms in human pulmonary macrophages (PM) and peripheral blood monocytes (PBM). Growth of Legionella pneumophila (LP) was assessed in PM or PBM which had been exposed to either rHu-IFN-gamma (500-1000 u/ml) or rHu-GM-CSF (1 to 10,000 u/ml). In both PM and PBM exposed to 500 u/ml rHu-IFN-gamma, growth of LP was reduced compared to cells exposed to media alone. By comparison, exposure of these cell types to rHu-GM-CSF had no detectable effect on bacterial replication. In order to investigate potential mechanisms accounting for this observation, the effect of these cytokines on the hydrogen peroxide (H2O2)-releasing capacity of cells was studied. Exposure of PM and PBM to rHu-IFN-gamma (500 to 1000 u/ml) resulted in increased production of H2O2 triggered by phorbol myristate acetate; when subjected to the same experimental conditions, rHu-GM-CSF-exposed cells exhibited no increase in H2O2 production. To further clarify the role of rHu-IFN-gamma-induced augmentation of oxidative metabolism on cellular inhibition of bacterial growth, an amount of catalase capable of completely neutralizing extracellular H2O2 was added to cells before and during infection. This did not abrogate the antibacterial activity of rHu-IFN-gamma. These studies demonstrate that rHu-IFN-gamma but not rHu-GM-CSF is capable of augmenting the capacity of PM and PBM to restrict LP growth. These data suggest that the antibacterial activity of rHu-IFN-gamma in this system may involve oxidative as well as nonoxidative mechanisms.
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PMID:Cytokine activation of antibacterial activity in human pulmonary macrophages: comparison of recombinant interferon-gamma and granulocyte-macrophage colony-stimulating factor. 314 84

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

Between March 1980 and June 1981, five strains of Legionella-like organisms were isolated from water. Four were recovered from potable water collected from hospitals in Chicago, Ill., and Los Angeles, Calif., during outbreaks of nosocomial legionellosis. The fifth strain was isolated from water collected from an industrial cooling tower in Jamestown, N.Y. The strains exhibited biochemical reactions typical of Legionella species and were gram-negative motile rods which grew on buffered charcoal-yeast extract agar but not on blood agar, required cysteine, and were catalase positive, urease negative, nitrate negative, hippurate negative, and nonfermentative. All strains were positive for oxidase and beta-lactamase and produced a brown, diffusible pigment. Of the five strains, four exhibited blue-white autofluorescence under long-wavelength UV light. The fatty-acid composition and ubiquinone content of these strains were consistent with those of other Legionella species. Direct fluorescent-antibody examination of the five strains with conjugates to previously described Legionella species demonstrated no cross-reactions except with the conjugates to L. longbeachae serogroup 2 and L. bozemanii serogroup 2. Four strains gave a 4+ reaction to the L. longbeachae serogroup 2 conjugate and the fifth strain gave a 1+ reaction. Each of the five strains gave a 4+ reaction with the conjugate to L. bozemanii serogroup 2. DNAs from the five strains were highly related (84 to 99%) and showed 5 to 57% relatedness to other Legionella species. These strains constitute a new species in the genus Legionella, and the name Legionella anisa sp. nov. is proposed. The type strain of L. anisa is WA-316-C3 (ATCC 35292).
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PMID:Legionella anisa: a new species of Legionella isolated from potable waters and a cooling tower. 398 9

The difficulties associated with the growth of Legionella species in common laboratory media may be due to the sensitivity of these organisms to low levels of hydrogen peroxide and superoxide radicals. Exposure of yeast extract (YE) broth to fluorescent light generated superoxide radicals (3 microM/h) and hydrogen peroxide (16 microM/h). Autoclaved YE medium was more prone to photochemical oxidation than YE medium sterilized by filtration. Activated charcoals and, to a lesser extent, graphite, but not starch, prevented photochemical oxidation of YE medium, decomposed hydrogen peroxide and superoxide radicals, and prevented light-accelerated autooxidation of cysteine. Also, suspensions of charcoal in phosphate buffer and in charcoal yeast extract medium readily decomposed exogenous peroxide (17 and 23 nmol/ml per min, respectively). Combinations of bovine superoxide dismutase and catalase also decreased the rate of photooxidation of YE medium. Medium protected from light did not accumulate appreciable levels of hydrogen peroxide, and autoclaved YE medium protected from light supported good growth of Legionella micdadei. Various species of Legionella (10(4) cells per ml) exhibited sensitivity to relatively low levels of hydrogen peroxide (26.5 microM) in challenge experiments. The level of hydrogen peroxide that accumulated in YE medium over a period of several hours (greater than 50 microM) was in excess of the level tolerated by Legionella pneumophila, which contained no measurable catalase activity. Strains of L. micdadei, Legionella dumoffi, and Legionella bozmanii contained this enzyme, but the presence of catalase did not appear to confer appreciable tolerance to exogenously generated hydrogen peroxide.
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PMID:Production of superoxide and hydrogen peroxide in medium used to culture Legionella pneumophila: catalytic decomposition by charcoal. 630 19

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


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