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

This replication method, which was introduced in 1985, has been used to find and identify microorganisms in the environment, among others in samples of soil, sediments and waters. A gene or a DNA fragment specific to a microorganism is replicated in vitro by a chain reaction catalyzed by DNA polymerase (PCR: Polymerase Chain Reaction) and analyzed by electrophoretic procedures. At the moment in most legislations bacteriological criteria for drinking water depend on E. coli and other bacteria referring to fecal contamination (fecal coliforms and enterococci). Absence of these bacteria does not necessarily exclude contamination of water with protozoa or virus. Detection of the latter by common methods is difficult and time-consuming. Application of PCR to these purposes is interesting. During the last years several protocols have been developed such as methods for the detection of E. coli, bacteria referring to fecal contamination, pathogens like Legionella pneumophila as well as Salmonella and Shigella, enterovirus and protozoa i.e. Giardia. Compared to the traditional methods an obvious advantage of the new methods lies in their velocity, sensitivity and specificity. This review introduces to several different applications of PCR. Although this method is still restricted to specialized laboratories at the moment, it will gain importance as a complement to traditional methods for the detection of pathogenic microorganisms in water as soon as simple tests will be available.
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PMID:[The use of PCR for detecting pathogenic microorganisms in water]. 820 34

Three detection methods for Legionella species in water samples from cooling towers and a river were examined. Direct counting of bacteria stained with fluorescent antibody (FA) for L. pneumophila (serogroups 1 to 6) could detect the cell of 10(4) to 10(6) cell/100 ml in all 14 samples, while colony counting method detected 10 to 10(3) CFU/100 ml only in 8 samples from cooling towers. Polymerase chain reaction (PCR) assay with primers to amplify 16S ribosomal DNA sequence of most Legionella species (LEG primer) detected legionellae in 13 samples, while species-specific primers for L. pneumophila detected the DNAs from 3 samples. In laboratory examination, LEG primers could amplify DNAs of 29 species of genus Legionella with high sensitivity, even from 1 cell of L. pneumophila GIFU 9134. The PCR assay with LEG primers was specific and sensitive methods to be satisfied the survey of legionellae. Thus, PCR assay is a suitable method to detect and monitor Legionella species in an environment.
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PMID:Comparison of detection methods for Legionella species in environmental water by colony isolation, fluorescent antibody staining, and polymerase chain reaction. 824 24

Many physicians are unaware of the limitations of the available tests for diagnosing infections with Legionella organisms. Geographic differences in the importance of nonpneumophila Legionella species as pathogens are underrecognized, in part because available diagnostic tests are biased toward the detection of pneumophila serogroup 1. Routine laboratory practices reduce the likelihood of culturing Legionella species from clinical isolates. Failure of seroconversion is common, particularly with nonpneumophila species; even when seroconversion occurs, it may take much longer than 4 weeks. Urinary antigen testing has insufficient sensitivity to affect clinical management in most regions of the United States, as it can reliably detect only L. pneumophila serogroup 1 infections. Polymerase chain reaction-based techniques offer hope of providing highly sensitive, rapid diagnostic tests for all Legionella species, but limitations in the current tests will make validating them difficult.
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PMID:Legionella and community-acquired pneumonia: a review of current diagnostic tests from a clinician's viewpoint. 1524 23

Studies on Legionella show a continuum from environment to human disease. Legionellosis is caused by Legionella species acquired from environmental sources, principally water sources such as cooling towers, where Legionella grows intracellularly in protozoa within biofilms. Aquatic biofilms, which are widespread not only in nature, but also in medical and dental devices, are ecological niches in which Legionella survives and proliferates and the ultimate sources to which outbreaks of legionellosis can be traced. Invasion and intracellular replication of L. pneumophila within protozoa in the environment play a major role in the transmission of Legionnaires' disease. Protozoa provide the habitats for the environmental survival and reproduction of Legionella species. L. pneumophila proliferates intracellularly in various species of protozoa within vacuoles studded with ribosomes, as it also does within macrophages. Growth within protozoa enhances the environmental survival capability and the pathogenicity (virulence) of Legionella. The growth requirements of Legionella, the ability of Legionella to enter a viable non-culturable state, the association of Legionella with protozoa and the occurrence of Legionella within biofilms complicates the detection of Legionella and epidemiological investigations of legionellosis. Polymerase chain reaction (PCR) methods have been developed for the molecular detection of Legionella and used in environmental and epidemiological studies. Various physical and chemical disinfection methods have been developed to eliminate Legionella from environmental sources, but gaining control of Legionella in environmental waters, where they are protected from disinfection by growing within protozoa and biofilms, remains a challenge, and one that must be overcome in order to eliminate sporadic outbreaks of legionellosis.
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PMID:Legionella: from environmental habitats to disease pathology, detection and control. 1120 47

Polymerase chain reaction (PCR) was used for detecting Legionella DNA in water, sputum, tracheal aspirate and bronchoalveolar lavage fluid. There is paucity of data on the use of PCR for detection of Legionella in serum and urine samples. In 82 patients admitted with community-acquired pneumonia, urinary PCR was used in addition to urinary antigen assay for Legionella pneumophila serogroup 1 and serological tests (indirect immunofluorescence and ELISA) in paired sera. PCR was positive in urine samples from 21 patients (26%): in six of seven patients with acute legionellosis by CDC criteria, and 15 patients with negative urine antigen showing no fourfold rise in antibody titers in immunofluorescence test.
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PMID:Polymerase chain reaction for detection of Legionellae DNA in urine samples from patients with community-acquired pneumonia. 1134 76

Legionellae, which are important causes of pneumonia in humans, continue to be incorrectly labeled as exotic pathogens. The ability to diagnose Legionella infection is limited by the nonspecific nature of clinical features and the shortcomings of diagnostic tests. Despite recent improvements, existing diagnostic tests for Legionella infection either lack sensitivity for detecting all clinically important legionellae or are unable to provide results within a clinically useful time frame. Understanding local Legionella epidemiology is important for making decisions about whether to test for Legionella infection and which diagnostic tests to use. In most situations, the use of both the urinary antigen test plus sputum culture is the best diagnostic combination. Polymerase chain reaction (PCR) is a promising tool, but standardized assays are not commercially available. Further work needs to focus on the development of urinary antigen tests assays that detect a wider range of pathogenic legionellae and on the development of standardized PCR assays.
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PMID:Diagnosis of Legionella infection. 1249 Dec 4

Populations of bacteria in biofilms from different sites of a drinking water production system were analysed. Polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) analyses revealed changing DNA band patterns, suggesting a population shift during bank filtration and processing at the waterworks. In addition, common DNA bands that were attributed to ubiquitous bacteria were found. Biofilms even developed directly after UV disinfection (1-2m distance). Their DNA band patterns only partly agreed with those of the biofilms from the downstream distribution system. Opportunistic pathogenic bacteria in biofilms were analysed using PCR and Southern blot hybridisation (SBH). Surface water appeared to have a direct influence on the composition of biofilms in the drinking water distribution system. In spite of preceding filtration and UV disinfection, opportunistic pathogens such as atypical mycobacteria and Legionella spp. were found in biofilms of drinking water, and Pseudomonas aeruginosa was detected sporadically. Enterococci were not found in any biofilm. Bacterial cell counts in the biofilms from surface water to drinking water dropped significantly, and esterase and alanine-aminopeptidase activity decreased. beta-glucosidase activity was not found in the biofilms. Contrary to the results for planktonic bacteria, inhibitory effects were not observed in biofilms. This suggested an increased tolerance of biofilm bacteria against toxic compounds.
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PMID:Investigation of natural biofilms formed during the production of drinking water from surface water embankment filtration. 1497 53

Approximately one third of community acquired pneumonia cases are caused by atypical pneumonia agents, Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydophila pneumoniae (formerly Chlamydia pneumoniae). The laboratory diagnosis of these organisms is difficult and time-consuming by conventional microbiological techniques. Polymerase chain reaction (PCR) is one of the important tools which can circumvent this problem. A multiplex PCR assay was developed to achieve the diagnosis of these three organisms in a single tube. Primers used in PCR were selected in a way that they amplified different length DNA fragments from different agents but they all worked at the same amplification conditions. Therefore the organisms could be diagnosed according to the length of amplified products by agarose gel electrophoresis without using any hybridization probes. After development of the multiplex PCR method, totally 309 clinical samples which were sent to our laboratory for single-agent PCR, were also evaluated by this technique. The results showed that the multiplex PCR assay is a sensitive, useful, cheap, and rapid diagnostic tool for the management of pneumonia patients.
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PMID:Rapid detection of bacterial atypical pneumonia agents by multiplex PCR. 1506 98

The aim of the work was to develop a PCR-based assay for detection of L. pneumophila and L. micdadei in environmental samples as well as in clinical samples from low respiratory tract and to assess its analytic characteristics. The assay was used during investigation of the outbreak developed in July 2007 in town Verkhnyaya Pyshma (Sverdlovsk region). Polymerase-chain reaction (PCR)with fluorescent detection,sequencing and cloning of DNA fragments were used. Developed assay based on the PCR with fluorescent real-time/ endpointdetection is able to detect L. pneumophila in clinical and environmental samples and to quantify amount of bacterial DNA in water. Specificity of analysis (100%) was assessed using the panel of bacterial strains and samples from healthy individuals. Analytic sensitivity of assay and quantitation limit was 1000 GU in 1 ml. Sensitivity of the assay of artificially contaminated biological samples was 1000 bacteria in 1 ml. During outbreak investigation L. pneumophila DNAwas detected in 4 lung samples from 4 fatal cases, from 1 of 2 sputum samples, 1 of 2 bronchoalveolar lavage samples with X-ray confirmed pneumonia. Legionella's DNA was found in samples from cooling towers, central hot water supply as well as from showerheads in apartments of 3 patients. Fountain and drinking water samples were PCR-negative. Specificity of PCR-positive results was confirmed by sequencing. Use of the assay during outbreak in- vestigation allowed to confirm the diagnosis in fatal cases and quickly identify the possible source of infection.
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PMID:[Development and use of the assay for Legionella pneumophila detection based on fluorescent real-time/endpoint polymerase-chain reaction]. 1846 37

The paper presents the results of studying the biological properties of Legionella pneumophila strains isolated from environmental objects. Elective legionellosis medium (ELM) has been found to be suitable for the isolation of the causative agent from the starting material and to be as sensitive as CYE (Oxoid company) containing growth and selective additives. Polymerase chain reaction (PCR) with a home-produced commercial test system used to detect L. pneumophila DNA enables identification of the causative agent, including its species. Hyperimmune sera against L. pneumophila 1-7 serogroups used in slide-agglutination and agglutination, as well as a series of co-agglutinating diagnosticums for legionellosis 1-7 serogroups make it possible to identify even the serogroups of L. pneumophilla. Comparative analysis of the virulence of L. pneumophila cultures in vivo and in vitro allows recommendation that practical laboratories should employ a simple NaCl resistance test, which can be used as a guide virulence test.
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PMID:[Study of Legionella pneumophila strains isolated from environmental objects]. 2014 9


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