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

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.

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

Reference Values

Not applicable

Day(s) Performed

Monday through Sunday

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.

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

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.

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)

Reject Due To

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

Method Name

Rapid Polymerase Chain Reaction (PCR)

Forms

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

Secondary ID

89564