Test Catalog

Test Id : FLARP

Free-Living Amebae, Molecular Detection, PCR, Varies

Useful For
Suggests clinical disorders or settings where the test may be helpful

Aids in the diagnosis of primary amebic meningoencephalitis and granulomatous amebic encephalitis in spinal fluid and tissue in conjunction with clinical findings

 

This test should not be used to screen asymptomatic patients.

Highlights

This assay is intended as an aid in the diagnosis of primary amebic meningoencephalitis and granulomatous amebic encephalitis in conjunction with clinical findings.

 

This test has similar sensitivity and specificity to culture but provides a more rapid result.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Real-Time Polymerase Chain Reaction (PCR)/TaqMan DNA Probe Hybridization

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Free-living Amebae Detection, PCR

Aliases
Lists additional common names for a test, as an aid in searching

Acanthamoeba

Naegleria

Balamuthia

Amoebic Encephalitis

Free Living Amoeba

Free Living Amoebae

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Specimen Type
Describes the specimen type validated for testing

Varies

Necessary Information

Specimen source is required.

ORDER QUESTIONS AND ANSWERS

Question ID Description Answers
SSFLA Specimen Source

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Submit only 1 of the following specimens:

 

Specimen Type: Cerebrospinal fluid

Container/Tube: Sterile container

Specimen Volume: 0.5 mL

Collection Instructions: Send vial #2.

 

Specimen Type: Tissue: Fresh

Sources: Brain, skin, lung

Container/Tube: Sterile container

Specimen Volume: 5-10 mm

Collection Instructions: Submit tissue in a sterile container with 1 mL of sterile saline or minimal essential media (MEM).

 

Preferred Paraffin-embedded tissue block:

Supplies: Tissue Block Container (T553)

Specimen Type: Formalin-fixed, paraffin-embedded tissue block (FFPE)

Sources: Brain, skin, lung

Container/Tube: Tissue block

Collection Instructions: Submit a FFPE tissue block to be cut and returned.

 

Acceptable Paraffin-embedded tissue block:

Specimen Type: Formalin-fixed, paraffin-embedded tissue block (FFPE)

Sources: Brain, skin, lung

Container/Tube: Sterile container for each individual cut section (scroll).

Collection Instructions: Perform microtomy and prepare five separate 10-micron sections. Each section (scroll) must be placed in a separate sterile container for submission.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

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

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

CSF: 0.3 mL; Tissue: 5 mm biopsy

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
 

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

Useful For
Suggests clinical disorders or settings where the test may be helpful

Aids in the diagnosis of primary amebic meningoencephalitis and granulomatous amebic encephalitis in spinal fluid and tissue in conjunction with clinical findings

 

This test should not be used to screen asymptomatic patients.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Several free-living amebae can infect the central nervous system (CNS) and cause devastating, usually fatal, disease. The route of entry and clinical course of infection varies with the type of ameba involved. Naegleria fowleri typically causes rapidly progressive primary amebic meningoencephalitis (PAM) in previously healthy children or adults. Infection is acquired during contact with contaminated water, including swimming and diving in warm stagnant freshwater lakes and by nasal irrigation with nonsterile water. During contact, the amebae enter the nasal sinuses and travel along the olfactory nerve through the cribriform plate of the skull and into the CNS. PAM is almost uniformly fatal within several days of exposure. Because of the rarity of the infection and difficulty in initial detection, about 75% of diagnoses are made after the death of the patient. In contrast, Acanthamoeba species and Balamuthia mandrillaris usually cause a subacute CNS illness, usually in adults who are immunocompromised, called granulomatous amebic encephalitis (GAE). The presentation of GAE can mimic a brain abscess, aseptic or chronic meningitis, or CNS malignancy. The amebae may enter the nasal sinuses like N fowleri or can disseminate to the CNS from the lungs or a primary skin lesion.

 

These amebae are usually identified by microscopic examination of cerebrospinal fluid or brain tissue and agar culture. Culture is more sensitive than microscopy alone but takes up to 7 days to produce a positive result. Also, B mandrillaris will not grow in routine culture. Real-time polymerase chain reaction assays offers a rapid and sensitive alternative to microscopy and culture.

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 positive result indicates the presence of free-living amoeba DNA and is consistent with active or recent infection. While positive results are highly specific indicators of disease, they should be correlated with symptoms and clinical findings of primary amebic meningoencephalitis and granulomatous amebic encephalitis.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Primary amebic meningoencephalitis due to Naegleria fowleri is a rapidly fatal disease, and rapid detection may improve the likelihood of survival. The fastest way to make a diagnosis is through examination of spinal fluid for characteristic trophozoites. This should be performed in addition to polymerase chain reaction testing.

 

While this assay is designed to detect symptomatic infection with free-living amoeba species, the widespread distribution of these microscopic amebae in the environment may contaminate inanimate objects. Thus, testing should be reserved for patients with a clinical history and symptoms consistent with granulomatous amebic encephalitis and primary amebic meningoencephalitis.

 

Inadequate specimen collection or improper storage may invalidate test results.

 

Free-living amoeba DNA may be detectable for an unknown period of time after adequate treatment.

Supportive Data

The following assay verification data supports the use of this assay for clinical testing.

 

Accuracy/Diagnostic Sensitivity and Specificity:

 

Species Inclusivity:

Thirty-seven strains of free-living amoeba were tested. All 20 Acanthamoeba species and all strains of Naegleria fowleri and Balamuthia mandrillaris were detected, while other Naegleria and Balamuthia species were not detected with this assay.

 

Results from this free-living amoeba polymerase chain reaction (PCR) assay were compared to culture results on 6 cerebrospinal fluid (CSF) specimens. All were negative by both culture and PCR (100% concordance).

 

Twenty-eight formalin-fixed paraffin-embedded (FFPE) tissue blocks were tested with the free-living amoeba PCR assay and results were compared to histopathologic diagnosis. Nineteen of the tissues were positive by histopathology diagnosis. Of these 19, 15 were positive by PCR. The internal control presence indicated no inhibition in these specimens. The sensitivity of PCR for clinical FFPE specimens is 83% and specificity is 100%.

 

Supplemental Data:

Spiking studies were performed using free-living amoeba negative CSF, fresh tissue, and FFPE tissue spiked with Acanthamoeba, N fowleri, and B mandrillaris genomic DNA. The sensitivity of the PCR assay was 97% to 100% and the specificity with spiked specimens was 100%. The samples were extracted and tested in a blinded fashion.

 

Analytical Sensitivity/Limit of Detection:

 

The limit of detection (LOD) established using genomic DNA spiked into CSF is:

A polyphaga ATCC 30173 - 2.5 target copies/mcL

B mandrillaris, ATCC PRA 290 - 3.05 target copies/mcL

N fowleri, ATCC 30896 - 1.16 target copies/mcL

 

The LOD established using genomic DNA spiked into fresh tissue matrix is:

A polyphaga, ATCC 30173 - 6.5 target copies/mcL

B mandrillaris, ATCC PRA 290 - 1.84 target copies/mcL

N fowleri, ATCC 30896 - 4.01 target copies/mcL

 

The LOD established using genomic DNA spiked into formalin-fixed paraffin-embedded tissue matrix is:

A polyphaga, ATCC 30173 - 5.7 target copies/mcL

B mandrillaris, ATCC PRA 290 - 21.94 target copies/mcL

N fowleri, ATCC 30896 - 7.82 target copies/mcL

 

Analytical Specificity:

No PCR signal was obtained from the extracts of 33 bacterial, viral, parasitic, and fungal isolates from similar organisms or from organisms commonly found in the specimens tested.

 

Precision:

Interassay precision was 100% and intra-assay precision was 100%.

 

Reference Range:

The reference range is "negative" for this assay. This assay is intended for detection of DNA from Acanthamoeba species, N fowleri, and B mandrillaris in CSF, and fresh and FFPE tissue (skin, lung, and brain) to aid in the diagnosis of primary amebic meningoencephalitis (PAM) and granulomatous amebic encephalitis (GAE) in conjunction with clinical findings.

 

Reportable Range:

This is a qualitative assay, and the results are reported as negative or positive for targeted free-living amoeba (Acanthamoeba species, N fowleri, and B mandrillaris) detected.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Trabelsi H, Dendana A, Sellami A, et al: Pathogenic free-living amoebae: epidemiology and clinical review. Pathol Biol (Paris). 2012;60:399-405

2. Thompson PP, Kowalski RP, Shanks RM, Gordon YJ: Validation of real-time PCR for laboratory diagnosis of Acanthamoeba keratitis. J Clin Microbiol. 2008;46:3232-3236

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

The assay is performed on the Roche LightCycler (LC) 480 II instrument following DNA extraction on the Roche MagNA Pure or the Siemens Tissue Preparation System (TPS). The LC 480 II instrument is an automated instrument that amplifies and monitors the development of target nucleic acid (amplicon) after each polymerase chain reaction (PCR) cycle.

 

The DNA target for this PCR assay is a gene encoding the nuclear small subunit ribosomal 18S rRNA.

 

The PCR is run as 2 separate assays: primers and probes for Acanthamoeba species and an internal control will comprise 1 reaction, while primes and probes for Balamuthia mandrillaris and Naegleria fowleri are contained in the second reaction. The forward and reverse primers are for template amplification and the TaqMan probes (FAM and CY5) are for detection. The FAM and CY5 probes contain a fluorophore (5'-end) and a quencher (3'-end) in close proximity; the quencher inhibits the fluorescence signal from the fluorophore while the probe is intact. After the probe anneals to the targeted ameba 18S rDNA, it is subsequently degraded by a DNA polymerase with 5'-3' exonuclease activity, resulting in release of the fluorophore and production of signal. Presence of the specific organism nucleic acid is confirmed by the presence of an amplification curve, which is used to determine if a specimen is positive or negative.(Qvarnstrom Y, Visvesvara GS, Sriram R, da Silva AJ: Multiplex real-time PCR assay for simultaneous detection of Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri. J Clin Microbiol. 2006;44:3589-3595; Connelly L, Anijeet D, Alexander CL. A descriptive case of persistent Acanthamoeba keratitis: raising awareness of this complex ocular disease. Access Microbiol. 2019 Nov 28;2(3):acmi000084)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) 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 US 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 Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

87798 x 3

87798 (if appropriate for government payers)

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
FLARP Free-living Amebae Detection, PCR 96910-5
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
SSFLA Specimen Source 31208-2
38061 Acanthamoeba species PCR 41429-2
38063 Balamuthia mandrillaris PCR 41432-6
38062 Naegleria fowleri PCR 87758-9

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
Test Status - Test Resumed 2022-08-24
Test Status - Test Down 2022-07-28