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Confirmation of active Lyme disease
Supporting the diagnosis of Lyme arthritis
Testing of cerebrospinal fluid (CSF) by PCR in patients with suspected Lyme neuroborreliosis should be requested only on patients with positive Borrelia burgdorferi antibody in serum confirmed by Western blot assay LYWB / Lyme Disease Antibody, Immunoblot, Serum and with abnormal CSF findings (elevated protein and WBC >10 cells/high-power field).
Lyme disease is a multisystem and multistage infection caused primarily by 3 species of tick-borne spirochetes in the Borrelia burgdorferi sensu lato genogroup. These spirochetes include Borrelia burgdorferi sensu stricto (North America and Western Europe), Borrelia afzelii (Central and Western Europe and Russia), and Borrelia garinii (Europe, Russia, and northern Asia). Endemic areas for Lyme disease in the United States correspond with the distribution of 2 tick species, Ixodes scapularis (Northeastern and Upper Midwestern US) and Ixodes pacificus (West Coast US). In Europe, Ixodes ricinus transmits the spirochete. Lyme disease is the most commonly reported tick-borne infection in Europe and North America (CDC).
Lyme disease exhibits a variety of symptoms that may be confused with immune and inflammatory disorders. Inflammation around the tick bite causes skin lesions. Erythema (chronicum) migrans (ECM), a unique expanding skin lesion with central clearing that has a ring-like appearance, is typically the first stage of the disease. Arthritis, neurological disease, and cardiac disease may be later stage manifestations.
Serology is currently the diagnostic method of choice for Lyme disease. However, serology may not be positive until 2 to 4 weeks after onset of ECM, and direct detection of Borrelia species. Target DNA using PCR may be a useful adjunct to existing diagnostic tests for acute disease. PCR has shown utility for detection of Borrelia DNA from skin biopsies of ECM lesions, as well as DNA from synovial and cerebrospinal fluid in late-stage disease.(1) Borrelia DNA can also, rarely, be detected from blood, but is not the test of choice from this source.
Lyme PCR may be useful for adjunctive testing to support a serologic diagnosis of Lyme disease, and should be performed in conjunction with FDA-approved serologic tests.
PCR results should be correlated with serologic and epidemiologic data and clinical presentation of the patient.
A positive result indicates the presence of DNA from Borrelia burgdorferi, the agent of Lyme disease.
A negative result indicates the absence of detectable DNA from Borrelia burgdorferi in the specimen. Due to the clinical sensitivity limitations of the PCR assay, a negative result does not preclude the presence of the organism or active Lyme disease.
A negative result does not rule-out Lyme disease, since inhibitory substances may be present in the specimen and the assay has limited clinical sensitivity when testing certain specimen types (eg, cerebrospinal fluid: CSF). If clinical features of illness are highly indicative of Lyme neuroborreliosis, serologic testing on CSF is warranted. Patients with active infection due to Borrelia afzelii or Borrelia garinii may have positive results from this PCR test, which will be reported as atypical gene sequence and prompt additional testing. PCR test results should be used as an aid in diagnosis and not considered diagnostic by themselves. These results should be correlated with serologic and epidemiologic data and clinical presentation of the patient.
Concurrent infections with multiple tick-borne pathogens, including Ehrlichia chaffeensis/Anaplasma phagocytophilum and Babesia microti have been reported in United States, and consideration should be given to testing for other pathogens if clinically indicated.
The following validation data supports the use of this assay for clinical testing.
Accuracy/Diagnostic Sensitivity and Specificity:
Results from this real-time PCR assay on the LightCycler (LC PCR) directed to the plasminogen-binding protein were compared to those generated using conventional PCR (target ospA gene) for synovial fluid (82), whole blood (22), and cerebrospinal fluid (CSF) (85). Using the conventional PCR as the gold standard, the diagnostic sensitivity and specificity for detection of Borrelia burgdorferi was as follows: synovial fluid (98.1% and 100%), whole blood (100% and 100%), and CSF (80% and 100%).
Additional spiking studies of whole organism in fresh tissue, synovial fluid, CSF, and whole blood (spiked near the approximate limit of detection) showed 100% recovery.
Analytical Sensitivity/Limit of Detection (LoD):
The lower LoD is approximately 300 to 1,000 genomic copies/mL in CSF, tissue, synovial fluid, and whole blood.
No PCR signal was obtained from the extracts of 22 bacterial, viral, parasitic, and fungal isolates that can cause symptoms similar to Lyme disease including: Rickettsia rickettsii, Rickettsia typhi, Ehrlichia canis, Babesia microti, Plasmodium falciparum, Plasmodium vivax, Bartonella henselae, Bartonella quintana, Herpes simplex virus, and Toxoplasma gondii.
Inter-assay precision was 100% and intra-assay precision was 100%.
Although the reference range is "negative" for this assay, it may detect low-grade asymptomatic bacteremia from individuals exposed to Lyme-endemic areas. However, this assay is only to be used for patients with a clinical history and symptoms consistent with Lyme, and must be interpreted in the context of serologic tests, which are the gold standard for diagnosis of Lyme disease. This test is not used to screen asymptomatic patients.
This is a qualitative assay, and the results are reported as negative or positive for targeted Borrelia burgdorferi.
1. Nocton JJ, Bloom BJ, Rutledge BJ, et al: Detection of Borrelia burgdorferi DNA by polymerase chain reaction in cerebrospinal fluid with Lyme neuroborreliosis. J Infect Dis 1996;174:623-627
2. CDC: Recommendation for test performance and interpretation. From second national conference on serological diagnosis of lyme disease. MMWR Morb Mortal Wkly Rep 1996;45:481-484
3. Nocton JJ, Dressler F, Rutledge BJ, et al: Detection of Borrelia burgdorferi DNA by polymerase chain reaction in synovial fluid from patients with Lyme arthritis. N Engl J Med 1994;330:229-234
4. Babady NE, Sloan LM, Vetter EA, et al: Percent positive rate of Lyme real-time polymerase chain reaction in blood, cerebrospinal fluid, synovial fluid, and tissue. Diagn Microbiol Infect Dis 2008;62(4):464-466