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Test Code LABLEGPC Legionella species, Molecular Detection, PCR, Varies

Additional Codes

 

Test Name in EPIC EPIC Test Code Mnemonic Mayo Test ID
LEGIONELLA SPECIES BY RAPID PCR LABLEGPC LEGRP LEGRP

 

Reporting Name

Legionella PCR

Useful For

Sensitive and rapid diagnosis of pneumonia caused by Legionella species

 

The assay is not recommended as a test of cure because bacteria nucleic acids may persist after successful treatment.

Method Name

Rapid Polymerase Chain Reaction (PCR)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Varies


Necessary Information


Specimen source is required.



Specimen Required


The high sensitivity of amplification by polymerase chain reaction requires the specimen to be processed in an environment in which contamination of the specimen by Legionella DNA is unlikely.

 

Specimen Type: Lower respiratory

Sources: Bronchoalveolar lavage, bronchial aspirate/brushing/lavage/washing, tracheal/endotracheal secretions/aspirate, sputum

Container/Tube: Sterile container

Specimen Volume: 1 mL

 

Specimen Type: Fresh tissue or biopsy

Sources: Lung, pleura, heart valve, pericardium

Container/Tube: Sterile container

Specimen Volume: Entire collection or 5 mm(3) - approximately the size of a pencil eraser

Collection Instructions: Aseptically collect a 1 to 2 cm(3) piece of tissue whenever possible

 

Specimen type: Fluid

Sources: Pericardial, pleural, chest, chest tube drainage, thoracentesis, empyema

Container/Tube: Sterile container

Specimen Volume: 1 mL


Specimen Minimum Volume

See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred) 7 days
  Frozen  7 days

Reject Due To

Tissue in formalin, formaldehyde, or acetone
Formalin-fixed paraffin-embedded (FFPE) block		 Reject

Reference Values

Not applicable

Day(s) Performed

Monday through Sunday

CPT Code Information

87801

LOINC Code Information

Test ID Test Order Name Order LOINC Value
LEGRP Legionella PCR 5020-3

 

Result ID Test Result Name Result LOINC Value
SRC57 Specimen Source 31208-2
29515 Legionella PCR, Result 5020-3

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

Clinical Information

Legionnaires disease was first recognized during a pneumonia outbreak at the Legionnaires convention in Philadelphia in 1976. Investigators with the Centers for Disease Control and Prevention isolated a novel, gram-negative bacillus, later named Legionella pneumophila. It is now widely recognized that L pneumophila (and other members of the genus Legionella) cause Legionnaires disease.

Interpretation

A positive polymerase chain reaction (PCR) result for the presence of a specific sequence found within the Legionella 5S ribosomal RNA 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 probes, or the presence of Legionella species in quantities less than the limit of detection of the assay.

Cautions

This assay does not differentiate between the Legionella species. 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.

Supportive Data

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 polymerase chain reaction (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 frequently 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 (L pneumophila serogroups 1-12, 15/16) and 9 additional Legionella species (Fluoribacter [Legionella] bozemanae, Fluoribacter [Legionella] dumoffii, Legionella gormanii, Legionella jordanis, egionella longbeachae,  Legionella micdadei, Legionella oakridgensis, Legionella hackeliae, and Legionella wadsworthii) included in the panel were detected with the PCR method.

Method Description

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 ribosomal RNA gene. The LightCycler (LC) instrument amplifies and monitors target nucleic acid sequences by fluorescence during polymerase chain rection (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 under an 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, Nov. 19-22, 2009; Rucinski SL, Murphy MP, Kies KD, Cunningham SA, Schuetz AN, Patel R. Eight years of clinical Legionella PCR testing illustrates a seasonal pattern. J Infect Dis. 2018 Jul 13;218(4):669-670. doi: 10.1093/infdis/jiy201)

Specimen Retention Time

7 days

Report Available

3 days

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.