Laboratory Test Guide

Francisella tularensis Antibodies (Sendout)

General Information

Lab Name

Francisella tularensis Antibodies

Lab Code

RFTUL

Epic Name

Francisella Tularensis Antibodies

External Test Id

TULAB

Description

Useful For:

Aiding in the diagnosis of tularemia caused by Francisella tularensis
This test should not be used as a test of cure as it is not quantitative and patients may remain seropositive for months to years following resolution of disease.

Test Highlights:

This test detects IgM and IgG class antibodies to Francisella tularensis in serum and may be used as an aid for the diagnosis of tularemia.
Serologic testing should be performed alongside other diagnostic methods, including culture of appropriate specimens. (Note: please notify microbiology laboratory in cases of suspected F tularensis to minimize exposure risk to bench technologists)

References

Mayo Clinic Laboratories Francisella tularensis Antibody Clinical & Interpretive Information

Synonyms

Febrile Agglutinins-Francisella tularensis, Francisella tularensis, Glandular Fever, Rabbit Fever, TULAB, Tularemia, Tularensis

Components

Code	Name
RFTULM	F. tularensis IgM Antibody
RFTULG	F. tularensis IgG Antibody
RFTULI	F. tularensis Antibody Interp.

Interpretation

Method

Enzyme-Linked Immunosorbent Assay (ELISA)

Reference Range

See individual components

Interferences and Limitations

Cautions:

False-negative results may occur in specimens collected too soon following symptom onset, prior to the development of a detectable immune response. Repeat testing on new specimens collected 2 to 4 weeks later may be helpful.

False-positive results may occur in patients previously or currently infected with Brucella species. Other less frequent causes of cross-reactivity that have been reported include prior infection with Yersinia, Salmonella, or Legionella species.

IgM-class antibodies may be detectable as soon as 1 week after symptom onset and may remain detectable for multiple years following resolution of disease in some individuals. Therefore, an IgM-positive result may not indicate current or recent infection in some cases.

There are multiple subspecies of Francisella tularensis, including F tularensis subspecies tularensis, F tularensis subspecies holarctica and F tularensis subspecies novicida, which are found throughout the northern hemisphere, including in the United States. The IgM and IgG anti-F tularensis enzyme-linked immunosorbent assay (ELISA) tests used at Mayo Clinic Laboratories are based on the lipopolysaccharide (LPS) antigen of F tularensis. Although not directly tested, previous studies indicate that there are no antigenic differences between the LPS of F tularensis subspecies tularensis and the other subspecies. Therefore, these assays should not be used to differentiate between infections with the various F tularensis subspecies.

Guidelines

Washington DOH Notifiable Conditions

Ordering & Collection

Specimen Type

Blood

Collection

3 mL blood in RED TOP tube or GOLD TOP SST

Handling Instructions

Outside Laboratories: Centrifuge sample and transfer serum to a separate plastic vial. Refrigerate serum.

Stability: Refrigerated (preferred): 7 days; Frozen: 30 days; Ambient: Unacceptable.

Reject Due To: Gross hemolysis, gross lipemia, gross icterus, heat-inactivated specimen.

Quantity

requested: 0.6 mL serum
minimum: 0.5 mL serum

Processing

Centrifuge sample and transfer serum to a separate plastic aliquot. Refrigerate serum.

Sendouts,

Order Mayo Test: TULAB.
Interfaced: Yes.