Legionella species, Molecular Detection, PCR
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Sensitive and rapid diagnosis of pneumonia caused by Legionella species
Rapid Polymerase Chain Reaction (PCR)
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Specimen Type: Bronchial washing, bronchoalveolar lavage, lung tissue, pleural fluid, sputum, transtracheal aspirate, or tracheal secretions
Container/Tube: Sterile container
Specimen Volume: 1 mL
Specimen Stability Information:
Respiratory specimen: Refrigerated
Lung tissue: Refrigerated <7 days (preferred)/Frozen
Additional Information: Specimen source is required.
Forms: If not ordering electronically, submit a Microbiology Request Form (Supply T244) with the specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Legionnaires' disease was first recognized during a pneumonia outbreak at the Legionnaires convention in Philadelphia in 1976. Investigators with the CDC isolated a novel, gram-negative bacillus, later named Legionella pneumophila. It is now widely recognized that Legionella pneumophila (and other members of the genus Legionella) cause Legionnaires' disease.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
A positive PCR result for the presence of a specific sequence found within the Legionella 5S rRNA gene indicates the presence of a Legionella species DNA, which may be due to Legionella infection or environmental/water Legionella DNA in the specimen.
A negative PCR result indicates the absence of detectable Legionella DNA in the specimen, but does not rule-out legionellosis as false-negative results may occur due to inhibition of PCR, sequence variability underlying the primers and/or probes, or the presence of Legionella species in quantities less than the limit of detection of the assay.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This assay does not differentiate between the Legionella species. The assay is not recommended as a test of cure because nucleic acid may persist after successful treatment. False-positive results are theoretically possible if patient specimens are contaminated with Legionella DNA, which may occur since Legionella species are environmental organisms present in aquatic environments. The following uncommonly encountered species of Legionella are not detected by this assay: Legionella anisa, Legionella feeleii, Legionella maceachernii, Legionella parisiensis, and Legionella sainthelensi.
In a Mayo Clinic study, 153 archived respiratory specimens previously tested for Legionella species by direct fluorescence antibody (DFA) testing were extracted and tested using this PCR method. The PCR assay was 100% sensitive and 99.3% specific, in comparison to DFA. Additionally, 30 lung tissues and 30 pleural fluids were spiked with 3 of the most commonly isolated Legionella species. Spiking studies showed similar analytical sensitivity for PCR and the DFA method. The analytical sensitivity was less than 50 targets/20 microliter reaction. No cross-reactivity was observed when tested on a panel of respiratory pathogens or normal flora bacteria of the upper respiratory tract. Thirteen serogroups of Legionella pneumophila (Legionella pneumophila serogroups 1-12, 15/16) and 9 additional Legionella species (Legionella bozemanae, Legionella dumoffii, Legionella gormanii, Legionella jordanis, Legionella longbeachae, Legionella micdadei, Legionella oakridgensis, Legionella hackeliae, and Legionella wadsworthii) included in the panel were detected with the PCR method. The following uncommon species of Legionella are not detected by this assay: Legionella anisa, Legionella feeleii, Legionella maceachernii, Legionella parisiensis, and Legionella sainthelensi.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Cunningham SA, Sloan LM, Uhl JA, et al: Validation of a real-time PCR assay for the detection of Legionella species in respiratory samples. Abstracts of the Annual Meeting of the Association for Molecular Pathology, 2009 General Meeting, Kissimmee, FL, Nov. 19-22, 2009
2. Hayden RT, Uhl JR, Qian X, et al: Direct detection of Legionella species from bronchoalveolar lavage and open lung biopsy specimens: comparison of LightCycler PCR, in situ hybridization, direct fluorescence antigen detection, and culture. J Clin Microbiol 2001;39(7):2618-2626
3. Diederen BM, Kluytmans JA, Vandenbroucke-Grauls CM, Peeters MF: Utility of real-time PCR for diagnosis of Legionnaires' disease in routine clinical practice. J Clin Microbiol 2008;46(2):671-677
4. MacDonell MT, Colwell RR: The nucleotide sequence of the 5S rRNA from Legionella pneumophila. Nucleic Acids Res 1987;15(3):1335
Method Description Describes how the test is performed and provides a method-specific reference
This method employs a target-specific detection system using fluorescent resonance energy transfer (FRET) hybridization probes designed for a specific sequence found within the Legionella 5S rRNA gene. The LightCycler instrument amplifies and monitors target nucleic acid sequences by fluorescence during PCR cycling. This is an automated PCR system that can rapidly detect amplified product development through stringent air-controlled temperature cycling and capillary cuvettes. The detection of amplified products is based on the FRET principle. For FRET product detection, a hybridization probe with a donor fluorophore, fluorescein, on the 3' end is excited by an external light source, which emits light that is absorbed by a second hybridization probed with an acceptor fluorophore, LC-Ted 640, on the 5' end. The acceptor fluorophore then emits light of a different wavelength that can be measured with a signal that is proportional to the amount of specific PCR product. The detection process is completed in <1 hour using a closed tube system.(Cunningham SA, Sloan LM, Uhl JA, et al: Validation of a real-time PCR assay for the detection of Legionella species in respiratory samples. Abstracts of the Annual Meeting of the Association for Molecular Pathology, 2009 General Meeting, Kissimmee, FL, Nov. 19-22, 2009)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Sunday; Varies
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
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