Lyme Disease Serology with Reflex MTTT

Lyme Disease Serology – Modified Two-Tier Testing (MTTT)

Lyme Disease antibody testing is performed using the modified two-tier testing algorithm (MTTT).  MTTT consists of a polyvalent screening EIA or CLIA assay followed by a second EIA/CLIA assay for confirmation.  The MTTT is considered a suitable alternative to the standard two-tier test algorithm (STTT; polyvalent ELISA and IgM/IgG Western blots) by the CDC (1) and has been shown to have increased sensitivity for detection of antibody in early Lyme Disease cases (2).

The McLendon Laboratories Clinical Immunology Laboratory uses the Diasorin Liaison Lyme Total Antibody Plus assay to screen for the presence of IgG and IgM antibodies to Borrelia. burgdorferi.  Positive and Equivocal samples are reflexed to two confirmatory assays. The Diasorin Liaison Lyme IgM assay and the Diasorin Liaison Lyme IgG assay.   IgM results should not be used to diagnose Lyme disease in patients with symptoms of >30 days duration.  Clinical correlation is required for interpretation of results.

• Positive

  Antibodies to B. burgdorferi are detected.  This sample is being reflexed to second tier Lyme IgG and IgM assays according to the MTTT algorithm.

• Equivocal

  The presence or absence of antibodies to B. burgdorferi can’t be definitively determined.  This sample is being reflexed to second-tier IgG and IgM assays according to the MTTT algorithm.

• Negative

  Antibodies to B. burgdorferi are NOT detected.  A negative result does not exclude the possibility of infection.  If early Lyme Disease is suspected, a second sample should be collected in two to four weeks and tested.

Confirmatory Lyme Disease Antibody Testing Results IgM Result Interpretation

• IgM Positive

  IgM antibodies to B. burgdorferi detected. IgM serologic results should be interpreted only in patients with symptoms of ≤30 days’ duration. In patients with symptoms lasting >30 days, IgM seroreactivity is not recommended for diagnosis and may represent false-positive reactivity or persistent antibody response.

• IgM Equivocal

  IgM-class antibodies to B. burgdorferi equivocal. IgM serologic results are most useful in patients with symptoms of ≤30 days’ duration. Equivocal results may represent early infection or nonspecific reactivity. Repeat testing may be considered if clinically indicated.

• IgM Negative

  IgM-class antibodies to B. burgdorferi not detected. A negative IgM result does not exclude early Lyme disease. If symptoms are of short duration and clinical suspicion remains, repeat serologic testing in two to four weeks should be considered.

IgG Result Interpretation

• IgG Positive

  IgG-class antibodies to B. burgdorferi detected. This result is consistent with infection with Borrelia burgdorferi at some time. IgG antibodies may remain detectable for months to years following infection and should not be used to assess disease activity or response to therapy.

• IgG Equivocal

  IgG-class antibodies to B. burgdorferi equivocal. Equivocal IgG results may represent early seroconversion or nonspecific reactivity. Repeat testing may be considered if clinically indicated.

• IgG Negative

  IgG-class antibodies to B. burgdorferi not detected. A negative IgG result argues against Lyme disease in patients with symptoms lasting >30 days. In early infection, IgG antibodies may not yet be detectable.  If clinical suspicion remains, repeat serologic testing in two to four weeks should be considered.

1. https://ndc.services.cdc.gov/case-definitions/lyme-disease-2022/
2. Farhan Khan, Ziyad Allehebi, Yahya Shabi, Ian Davis, Jason LeBlanc, Robbin Lindsay, Todd Hatchette, Modified Two-Tiered Testing Enzyme Immunoassay Algorithm for Serologic Diagnosis of Lyme Disease, Open Forum Infectious Diseases, Volume 9, Issue 7, July 2022, ofac272, https://doi.org/10.1093/ofid/ofac272