Test ID: SLEG
Legionella pneumophila (Legionnaires Disease), Antibody, Serum
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Evaluation of possible legionellosis (Legionnaires disease, Pontiac fever, extrapulmonary legionella infection caused by Legionella pneumophila)
Method Name A short description of the method used to perform the test
Enzyme-Linked Immunosorbent Assay (ELISA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Legionnaire's Disease
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.
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
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.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 14 days |
| Frozen | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Legionella pneumophila may cause pulmonary disease in both normal and immunocompetent hosts. The disease may occur sporadically in the form of community acquired pneumonia and in epidemics. Pneumonia (often referred to as Legionnaires disease) occurs more frequently in severely immunosuppressed individuals; a milder form of the illness, referred to as Pontiac fever, is more prevalent in normal hosts. Extrapulmonary infection with Legionella pneumophila is rare. Legionnaire's disease, Pontiac fever, and extrapulmonary infection have been collectively referred to as legionellosis.
Approximately 85% of the documented cases of legionellosis have been caused by Legionella pneumophila. Serogroups 1 and 6 of Legionella pneumophila, by themselves, account for up to 75% of cases of legionellosis.
The definitive diagnosis of Legionella pneumophila is made by isolation of the organism on specialized culture medium (buffered charcoal yeast extract agar). Pulmonary secretions can be directly examined using a direct fluorescent antibody procedure, but the sensitivity of this method is low (25%-70%). Often it is difficult for the patient to produce pulmonary secretion (sputum) for examination, the pneumonia is frequently interstitial and sputum is scant. In the absence of invasive procedures (eg, bronchial alveolar lavage), urine evaluation for Legionella pneumophila antigen or indirect serological (antibody) methods may be useful.
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.
Negative
Interpretation Provides information to assist in interpretation of the test results
A negative result indicates that IgG/A/M antibody to Legionella pneumophila serogroups 1-6 is not detected. Negative results do not exclude Legionella infection. It may require 4 to 8 weeks to develop a detectable antibody response; serum specimens taken early in the course of infection may not yet have significant antibody titers. Furthermore, antibody levels can fall to undetectable levels within a month of infection, early antibiotic therapy may suppress antibody response, and some individuals may not develop antibodies above detectable limits.
Some culture-positive cases of Legionella do not develop Legionella antibody.
Positive results are suggestive of Legionella infection; however, a single positive result only indicates immunologic exposure at some time. It does not distinguish between previous or current infection. The level of antibody response may not be used to determine active infection. Other laboratory procedures or additional clinical information are necessary to establish a diagnosis.
Specimens with equivocal results are retested prior to reporting. Repeat testing on a second specimen should be considered in patients with equivocal results, if clinically indicated.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A diagnosis should not be made on the basis of positive Legionella antibody results alone. Test results for Legionella antibodies should be interpreted in conjunction with the clinical evaluation and the results of other diagnostic procedures.
A positive result suggests infection with 1 or more of the groups 1-6 species; however, one will not be able to distinguish between species with the results of this enzyme-linked immunosorbent assay (ELISA) test alone.
Use of serogroups 1-6 for assessing antibody responses to different Legionella species and serogroups has not been established.
Cross-reactivity may occur in sera with infections due to other Legionella species.
Positive results may be due to cross-reactivity with antibody generated as a result of non-Legionella infection. Serologic cross-reactions have been reported with Pseudomonas aeruginosa, several Rickettsia species, Coxiella burnetii, enteric gram-negative rods, Bacteroides species, Haemophilus species, Citrobacter freundii, and Campylobacter jejuni. Additionally, some reports indicate that a number of apparently healthy individuals may carry antibodies to legionellae; however, a positive result, along with clinical signs and symptoms may indicate possible Legionella infection. Additional serologic testing, such as paired sera analysis by immunofluorescence assay (IFA), or other clinical testing such as direct fluorescent antibody (DFA) and culturing, may be necessary to establish diagnosis.
The assay performance characteristics have not been established for matrices other than sera.
Although the conjugate is designed to detect human IgG, IgM, and/or IgA, one will not be able to determine which antibody is present with this assay.
The affinity and/or avidity of the anti-IgG/IgM/IgA conjugate has not been determined.
The use of hemolytic, lipemic, bacterially contaminated, or heat-inactivated specimens should be avoided. Erroneous results may occur.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Color Atlas and Textbook of Diagnostic Microbiology. 5th edition Lippincott. Edited by EW Koneman, SD Allen, WM Janda, et al: Philadelphia, Lippincott-Raven Publishers 1997
2. Package insert: Legionella IgG, A, M ELISA II, Wampole Laboratories, Princeton, NJ 2005-016
3. Principals and Practice of Infectious Diseases. 3rd edition. Edited by GL Mandell, RG Douglas, JE Bennett. Churchill Livingston, 1990
Method Description Describes how the test is performed and provides a method-specific reference
The Legionella kit is designed to detect IgG/A/M class antibodies to Legionella pneumophila in human sera. The test procedure involves 3 incubation steps:
1. Test sera (properly diluted) are incubated in multiwells coated with an inactivated, solubilized cocktail of Legionella pneumophila groups 1-6 bacteria (antigen). Legionella specific IgG, IgM, or IgA antibodies in the specimen will bind to the immobilized antigen. The plate is washed to remove unbound antibody and other serum components.
2. Peroxidase conjugated goat antihuman IgG/A/M is added to the wells and the plate is incubated. The conjugate will react with antibody immobilized on the solid phase in step 1. The wells are washed to remove unreacted conjugate.
3. The multiwells containing immobilized peroxidase conjugate are incubated with peroxidase substrate solution. Hydrolysis of the substrate by peroxidase produces a color change. After a period of time, the reaction is stopped and the color intensity of the solution is measured photometrically. The color intensity of the solution depends upon the antibody concentration in the test specimen.(Package insert: Legionella IgG, A, M ELISA II, Wampole Laboratories, Princeton, NJ 2005-016-16)
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, Wednesday, Friday; 2 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
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.
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.
86713
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.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| SLEG | Legionella Pneumophila Ab, S | 7947-5 |
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