No Single Diagnostic Test Suitable for Early Lyme Disease

January 17, 2002

NEW YORK (Reuters Health) Jan 14 - Refinements in laboratory-based diagnostic

assays since the 1990s have made it easier to detect Borrelia burgdorferi

infection in patients with erythema migrans. However, no single test is

appropriate for every patient.

That is according to Dr. Nowakowski of the Westchester Medical Center in

Valhalla, New York, and members of the Lyme Disease Study Group who compared

different diagnostic modalities for the detection of B. burgdorferi in 47 adults

with erythema migrans.

In the December 15th issue of Clinical Infectious Diseases, they report that

quantitative PCR using skin-biopsy specimens had the greatest sensitivity

(80.9%), exceeding the sensitivity of nested PCR (63.8%).

The sensitivity of 2-stage serologic testing on acute-phase samples was 40.4%

but increased to 68.1% when acute- plus convalescent-phase samples were

obtained. The authors report that 2-stage serologic testing " remains a fairly

sensitive diagnostic technique in patients who receive antibiotic therapy at

time of presentation, provided an appropriately timed convalescent-phase serum

sample can be obtained. "

A positive result on a cultured skin biopsy specimen measuring 2 mm in diameter

had a sensitivity of 51.1%. The sensitivity of cultures increased to 66% when

the results of large-volume blood cultures were included.

Dr. Nowakowski and colleagues say the fact that 3 patients (6.4%) had negative

results on all assays is " of interest. " It could be that some or all of these

patients were not infected with the tick-borne bacterium. " It is now well

recognized that an identical-appearing skin lesion can occur in the absence of

B. burgdorferi infection throughout the southern US, " the researchers note.

The team concludes that the clinical diagnosis of erythema migrans made by

experienced physicians is " highly accurate " in areas where B. burgdorferi is

endemic. However, not all patients will have B. burgdorferi infection.

Clin Infect Dis 2001;33:2023-2027.

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