Francisella tularensis Antibodies (Sendout)

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)

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.

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.

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

Sendouts,

• Order Mayo Test: TULAB.
• Interfaced: Yes.

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

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