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

Seventeen suspension of Legionella pneumophila and ten of Legionella bozemanii in saline or bronchoalveolar lavage (BAL) fluid were tested using the Gen Probe technique. The detection threshold was found to be 10(3)-10(4) CFU/ml. Specificity and sensitivity were evaluated by using the probe on 8 suspensions of bacteria other than Legionella and by performing a comparative study of the probe test, direct immunofluorescence and culture with 103 specimens (BAL fluid in most instances) from 92 patients with possible legionellosis. Sensitivity was found to be acceptable (3 of the 4 culture-positive specimens were positive by the probe test) and specificity was 100% despite the fact that most (80/99) BAL specimens were not sterile and regardless of the cutoff level used to define positivity. The advantages of the DNA probe test, including rapidity, simplicity and objectivity, should be weighed against its disadvantage, i.e., only acceptable sensitivity and use of radioactivity.
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PMID:[Evaluation of a DNA probe test for the detection of Legionella SPP]. 201 40

Specific DNA probes have been made for both M. pneumoniae and Legionella species. Dot blot methods have been used in research laboratories to test culture isolates of both organisms, and also to test animal tissues with a L. pneumophila-specific probe. Commercial kits are also available for direct specimen testing for these two organisms. The commercial kits are made by a single manufacturer, Gen-Probe, Inc. (San Diego, CA), and use a novel in-solution rapid hybridization assay, using 125I-labeled cDNA to rRNAs of the organisms. The Gen-Probe M. pneumoniae probe appears to be 80% to 100% sensitive, and 97% to 100% specific, based on analysis of two clinical studies using positive culture as the diagnostic criterion. The Gen-Probe legionella probe appears to be 33% to 71% sensitive (mean 57%), and 98.9% to 99.7% specific (mean 99.7%), based on analysis of four prospective clinical studies, using positive culture as the definition of disease, with a total sample size of 3,243 patients, 49 of which were culture-positive. Both Gen-Probe direct tests appear to be clinically useful, although the poor performance of the legionella test in one major university laboratory, and the expense of performing these tests, mandate that thorough evaluations be carried out in each laboratory anticipating using the test. Culture must always be performed for legionella whether or not the DNA probe test is used. It is likely that the use of the M. pneumoniae kit would greatly speed diagnosis, but whether this would alter medical practice or result in lower morbidity and health care costs is unknown.
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PMID:Use of DNA probes for the diagnosis of infections caused by Mycoplasma pneumoniae and legionellae--a review. 219 45

A fragment of the gene for cytolysin has been cloned. The product of the gene has been earlier identified as an immunoserological marker of Legionella pneumophila. Clones were selected by immunodetection of cytolysin gene product expression. An EcoRI 3.8 kb fragment of the genomic DNA from Legionella pneumophila strain Philadelphia-1 was used as a DNA probe that hybridized with the bacterial colonies of 20 Legionella pneumophila strains but not with the colonies of 10 other Legionella species or 8 other bacterial genera. The cloned fragment has been shown to be unique for Legionella pneumophila. The region of homology is suggested to be longer than a possible dimension of the cytolysin gene.
Mol Gen Mikrobiol Virusol 1990 May
PMID:[Specific DNA probe for detecting Legionella pneumophila]. 238 40

A commercial DNA probe kit designed to detect rRNA from legionellae was evaluated for its ability to correctly discriminate between legionellae and non-legionellae taken from culture plates. The probe kit, made by the Gen-Probe Corp. (San Diego, Calif.), was radiolabeled with 125I, and probe bacterial RNA hybridization, detected in a simple one-tube system hybridization assay, was quantitated with a gamma counter. A total of 156 Legionella sp. strains were tested, of which 125 were Legionella pneumophila and the remainder were strains from 21 other Legionella spp. A total of 106 gram-negative non-legionellae, isolated from human respiratory tract (81%) and other body site (19%) specimens, were also tested; 14 genera and 28 species were represented. The probe easily distinguished all of the legionellae from the non-legionellae. The average legionellae/non-legionellae hybridization ratio was 42:1, and the lowest ratio was 2:1; a minor modification in the procedure increased the lowest ratio to 5:1. In addition to correctly identifying all Legionella species, the probe was able to separate some of the various species of Legionella. L. pneumophila strains hybridized more completely to the probe than did the other Legionella spp.; L. wadsworthii and L. oakridgensis hybridized only about 25% of the probe relative to L. pneumophila. Some strains of phenotypically identified L. pneumophila had much lower hybridization to the probe than other members of the species and may represent a new Legionella species. The simplicity of the technique and specificity of the probe make it a good candidate for confirming the identity of legionellae in culture.
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PMID:Evaluation of the Gen-Probe DNA probe for the detection of legionellae in culture. 242 Aug 20

Confirmation of a culture as Legionella when it is unreactive with available serologic reagents involves tests that are impractical in most clinical laboratories. A nucleic acid probe that hybridizes only to members of the genus Legionella was recently prepared for marketing by Gen-Probe, Inc., San Diego, Calif. We tested 215 Legionella strains, representing 22 species, and 84 non-Legionella strains, representing 17 bacterial genera, with the Gen-Probe kit. All but four Legionella strains (L. bozemanii, less than 2% of total) and no heterologous strains gave positive test results. We conclude that the Legionella gene probe is a valuable addition to existing diagnostic tests for Legionella organisms.
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PMID:Evaluation of a commercial gene probe for identification of Legionella cultures. 242 99

A cloned EcoRI fragment from Legionella pneumophila, which includes 16S and 23S rRNA genes, was used to identify bacteria belonging to the genus Legionella by hybridization to a series of species specific restriction fragments. Examination of the type strains of 28 species of legionellae gave different band patterns in every case. When further isolates of these species were tested the patterns obtained were usually either identical, or very similar, to those of the respective type strains. Thirty-one coded isolates were examined and of these 29 were allocated to the correct species. The remaining strains (a non-Legionella and a L. pneumophila) could not be identified using this technique. The rRNA gene probe method should be of great value in the identification of legionellae, particularly for those species which are at present very difficult to distinguish serologically.
J Gen Microbiol 1988 Aug
PMID:Identification of species of the genus Legionella using a cloned rRNA gene from Legionella pneumophila. 247 64

Interspecific complementation of an Escherichia coli recA mutant with a Legionella pneumophila genomic library was used to identify a recombinant plasmid encoding the L. pneumophila recA gene. Recombinant E. coli strains harbouring the L. pneumophila recA gene were isolated by replica-plating bacterial colonies on medium containing methyl methanesulphonate (MMS). MMS-resistant clones were identified as encoding the L. pneumophila recA analogue by their ability to protect E. coli HB101 from UV exposure and promote homologous recombination. Subcloning of selected restriction fragments and Tn5 mutagenesis localized the recA gene to a 1.7 kb Bg/II-EcoRI fragment. Analysis of minicell preparations harbouring a 1.9 kb EcoRI fragment containing the recA coding segment revealed a single 37.5 kDa protein. Insertional inactivation of the cloned recA gene by Tn5 resulted in the disappearance of the 37.5 kDa protein, concomitant with the loss of RecA function. The L. pneumophila recA gene product did not promote induction of a lambda lysogen; instead, the presence of the heterologous recA gene caused a significant reduction in spontaneous and mitomycin-C-induced prophage induction in recA+ and recA E. coli backgrounds. Despite the lack of significant genetic homology between the L. pneumophila recA gene and the E. coli counterpart, the L. pneumophila RecA protein was nearly identical to that of E. coli in molecular mass, and the two proteins showed antigenic cross-reactivity. Western blot analysis of UV-treated L. pneumophila revealed a significant increase in RecA antigen in irradiated versus control cells, suggesting that the L. pneumophila recA gene is regulated in a manner similar to that of E. coli recA.
J Gen Microbiol 1989 Nov
PMID:Molecular cloning and expression in Escherichia coli of the recA gene of Legionella pneumophila. 255 47

Three extracellular proteases produced by Legionella pneumophila during growth in liquid medium were examined for their effects on human alpha-1-antitrypsin (alpha-1-AT). One of these proteases, tissue-destructive protease (TDP) destroyed completely the trypsin-inhibitory capacity of alpha-1-AT at protease: inhibitor molar ratios down to 0.002:1. After inactivation by TDP, the Mr of alpha-1-AT was reduced by 5000 in SDS-PAGE. This suggested that inactivation entailed only limited cleavage.
J Gen Microbiol 1988 Feb
PMID:Inactivation of human alpha-1-antitrypsin by a tissue-destructive protease of Legionella pneumophila. 304 37

A tissue-destructive protease of Legionella pneumophila was assayed for in the lungs of experimentally infected guinea-pigs by ELISA. It was found in amounts equivalent to the known lethal dose of purified protease administered by the intranasal route. The identity of the protease was confirmed by immunoblot analysis. This is further evidence that Legionella pneumophila protease may play a major role in the pathogenesis of Legionnaires' disease.
J Gen Microbiol 1988 Jan
PMID:In vivo production of a tissue-destructive protease by Legionella pneumophila in the lungs of experimentally infected guinea-pigs. 305 69

A prospective evaluation of a DNA probe assay for detection of Legionella species was performed on 427 consecutive respiratory specimens submitted over an 18-month period. The Gen-Probe assay utilizing both low (greater than or equal to 4.0) and high (greater than 7.0) ratio threshold values was compared to direct fluorescent antibody staining (DFA) as a predictor of isolation of Legionella on culture. The highest sensitivity (63%) was obtained with the lower threshold ratio, but was not significantly different from the result obtained with a threshold ratio of greater than 7.0 (50%, p = 0.722) or DFA results (44%, p = 0.479). The specificity of the DNA probe assay was improved with the high threshold (99%) compared either to the low threshold ratio (95%, p = 0.002) or DFA (97%, p = 0.055). When the DNA probe was compared to DFA and/or Legionella isolation on culture, a significantly lower specificity (97% versus 99%, p = 0.0006) and higher sensitivity (74% versus 37%, p = 0.013) was obtained with a threshold value of greater than or equal to 4.0 than greater than 7.0. Ten of 20 specimens with a DNA probe ratio between 4.0 and 7.0 were DFA positive, although only two were isolated on culture. The DFA assay and both probe threshold ratios have a high negative predictive value when compared to culture. However, only the threshold ratio of greater than 7.0 has a sufficiently high positive predictive value to be useful alone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prospective evaluation of the Gen-Probe assay for detection of legionellae in respiratory specimens. 314 56


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