Isolation of Legionella pneumophila by Co-culture with Local Ameba, Canada.
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ABSTRACT:
SUBMITTER: Dey R
PROVIDER: S-EPMC6810206 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe efficiency of recovery and the detection limit of Legionella after co-culture with Acanthamoeba polyphaga are not known and so far no investigations have been carried out to determine the efficiency of the recovery of Legionella spp. by co-culture and compare it with that of conventional culturing methods. This study aimed to assess the detection limits of co-culture compared to culture for Legionella pneumophila in compost and air samples. Compost and air samples were spiked with known concentrations of L. pneumophila. Direct culturing and co-culture with amoebae were used in parallel to isolate L. pneumophila and recovery standard curves for both methods were produced for each sample.ResultsThe co-culture proved to be more sensitive than the reference method, detecting 10²-10³ L. pneumophila cells in 1 g of spiked compost or 1 m³ of spiked air, as compared to 10⁵-10⁶ cells in 1 g of spiked compost and 1 m³ of spiked air.ConclusionsCo-culture with amoebae is a useful, sensitive and reliable technique to enrich L. pneumophila in environmental samples that contain only low amounts of bacterial cells.
| S-EPMC3598970 | biostudies-literature
Project description:An outbreak of Legionnaires' disease at a long-term care facility in Ontario, Canada from September to October 2005 resulted in the death of 23 residents and the illness of 112 other people. In response, molecular methods were developed to detect Legionella pneumophila in clinical lung samples and to subtype isolates from clinical and environmental samples. The targeted genetic loci included Legionella-specific virulence determinants (mip, icmO, sidA and lidA) and core bacterial determinants (ftsZ, trpS and dnaX). An established amplified fragment length polymorphism typing method provided the first indication of genetic relatedness between strains recovered from clinical samples and strains cultured from environmental samples taken from the outbreak site. These associations were verified using the European Working Group for Legionella Infections sequence-based typing protocol targeting the flaA, pilE, asd, mip, mompS and proA loci. These molecular typing methods confirmed the outbreak source as a contaminated air conditioning cooling tower.
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Project description:Legionella pneumophila outbreak investigations require the development of reliable typing methods to better understand the genetic relationships of the isolates involved. Here, we report the draft genome sequences of four clinical Legionella pneumophila isolates obtained between 2000 and 2012 in Ontario, Canada.
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Project description:Between 2000 and 2017, a total of 236 Legionella species isolates from Arizona were submitted to the CDC for reference testing. Most of these isolates were recovered from bronchoalveolar lavage specimens. Although the incidence of legionellosis in Arizona is less than the overall U.S. incidence, Arizona submits the largest number of isolates to the CDC for testing compared to those from other states. In addition to a higher proportion of culture confirmation of legionellosis cases in Arizona than in other states, all Legionella pneumophila isolates are forwarded to the CDC for confirmatory testing. Compared to that from other states, a higher proportion of isolates from Arizona were identified as belonging to L. pneumophila serogroups 6 (28.2%) and 8 (8.9%). Genome sequencing was conducted on 113 L. pneumophila clinical isolates not known to be associated with outbreaks in order to understand the genomic diversity of strains causing legionellosis in Arizona. Whole-genome multilocus sequence typing (wgMLST) revealed 17 clusters of isolates sharing at least 99% identical allele content. Only two of these clusters contained isolates from more than one individual with exposure at the same facility. Additionally, wgMLST analysis revealed a group of 31 isolates predominantly belonging to serogroup 6 and containing isolates from three separate clusters. Single nucleotide polymorphism (SNP) and pangenome analysis were used to further resolve genome sequences belonging to a subset of isolates. This study demonstrates that culture of clinical specimens for Legionella spp. reveals a highly diverse population of strains causing legionellosis in Arizona which could be underappreciated using other diagnostic approaches.IMPORTANCE Culture of clinical specimens from patients with Legionnaires' disease is rarely performed, restricting our understanding of the diversity and ecology of Legionella Culture of Legionella from patient specimens in Arizona revealed a greater proportion of non-serogroup 1 Legionella pneumophila isolates than in other U.S. isolates examined. Disease caused by such isolates may go undetected using other diagnostic methods. Moreover, genome sequence analysis revealed that these isolates were genetically diverse, and understanding these populations may help in future environmental source attribution studies.
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Project description:A gene capable of conferring spectinomycin resistance was isolated from Legionella pneumophila, the agent of Legionnaires' disease. The gene (aph) encoded a 36-kDa protein which has similarity to aminoglycoside phosphotransferases. Biochemical analysis confirmed that aph encodes a phosphotransferase which modifies spectinomycin but not hygromycin, kanamycin, or streptomycin. The strain that was the source of aph demonstrated resistance to spectinomycin, and Southern hybridizations determined that aph also exists in other legionellae.
| S-EPMC163921 | biostudies-other
Project description:The detection and quantification of Legionella pneumophila (responsible for legionnaire's disease) in water samples can be achieved by various methods. However, the culture-based ISO 11731:2017, which is based on counts of colony-forming units per ml (CFU·ml-1 ) is still the gold standard for quantification of Legionella species (spp.). As a powerful alternative, we propose real-time monitoring of the growth of L. pneumophila using an isothermal microcalorimeter (IMC). Our results demonstrate that, depending on the initial concentration of L. pneumophila, detection times of 24-48 h can be reliably achieved. IMC may, therefore, be used as an early warning system for L. pneumophila contamination. By replacing only visual detection of growth by a thermal sensor, but otherwise maintaining the standardized protocol of the ISO 11731:2017, the new procedure could easily be incorporated into existing standards. The exact determination of the beginning of metabolic heat is often very difficult because at the beginning of the calorimetric signal the thermal stabilization and the metabolic heat development overlap. Here, we propose a new data evaluation based on the first derivation of the heat flow signal. The improved evaluation method can further reduce detection times and significantly increase the reliability of the IMC approach.
| S-EPMC7264898 | biostudies-literature
Project description:Legionella pneumophila cells were harvested during exponential growth (RP) and stationary growth (TP). VBNC cells were also anylzed. Protein subfractions were studied.
2015-11-13 | PXD001926 | Pride
Project description:We examined 49 Legionella species, 26 L. pneumophila and 23 non-pneumophila Legionella spp., using partial 16S rRNA gene sequencing. This approach accurately identified all the L. pneumophila isolates, characterized all non-pneumophila Legionella isolates as such within this genus, and classified most (20/23; 87%) of the non-pneumophila Legionella isolates to the species level.
| S-EPMC1828979 | biostudies-literature
Project description:We describe 4 cases of Legionella pneumophila serogroup 13-associated pneumonia. These cases originate from a broad geographic range that includes Scotland, Australia, and New Zealand. L. pneumophila serogroup 13 pneumonia has a clinically diverse spectrum that ranges from relatively mild, community-acquired pneumonia to potentially fatal severe pneumonia with multisystem organ failure. All cases were confirmed by culture and direct fluorescent antibody staining or indirect immunofluorescent antibody tests. Proven or putative sources of L. pneumophila serogroup 13 infections in 2 patients included a contaminated whirlpool spa filter and river water. An environmental source was not found in the remaining 2 cases; environmental cultures yielded only other L. pneumophila serogroups or nonpneumophila Legionella species. We describe the clinical and laboratory features of L. pneumophila serogroup 13 infections. L. pneumophila serogroup 13 pneumonia is rarely reported, but it may be an underrecognized pathogenic serogroup of L. pneumophila.
| S-EPMC3310633 | biostudies-literature
Project description:We developed a single-tube multiplex real-time PCR assay capable of simultaneously detecting and discriminating Legionella spp., Legionella pneumophila, and Legionella pneumophila serogroup 1 in primary specimens. Evaluation of 21 clinical specimens and 115 clinical isolates demonstrated this assay to be a rapid, high-throughput diagnostic test with 100% specificity that may aid during legionellosis outbreaks and epidemiologic investigations.
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