In some symptomatic patients, the diagnosis of early Lyme disease can be established clinically by observing the unique skin lesion. When this skin lesion is not present and at later stages of the disease, which must be differentiated from many other diseases, it is necessary to perform diagnostic laboratory tests. There is, however, no one test that is both sensitive and specific.

 A. Specimens

 Blood is obtained for serologic tests. CSF or joint fluid can be obtained, but culture usually is not recommended. These specimens and others can be used to detect B. burgdorferi DNA by PCR.

B. Smears

 B. burgdorferi has been found in sections of biopsy specimens, but examination of stained smears is an insensitive method for diagnosis of Lyme disease. B. burgdorferi in tissue sections can sometimes be identified using antibodies and immunohistochemical methods.

C. Culture

 Culture is generally not performed because it takes 6–8 weeks to complete and lacks sensitivity.

D. Nucleic Acid Amplification Methods

The PCR assay has been applied to detection of B. burgdorferi DNA in many body fluids. It is rapid, sensitive, and specific, but it does not differentiate between DNA from live B. burgdorferi in active disease and DNA from dead B. burgdorferi in treated or inactive disease. It has about 85% sensitivity when applied to synovial fluid samples, but the sensitivity is much lower when it is applied to CSF samples from patients with neuroborreliosis.

 E. Serology

Serology has been the mainstay for the diagnosis of Lyme disease, but 3–5% of normal people and persons with other diseases (eg, rheumatoid arthritis, many infectious diseases) may be seropositive by initial EIA or indirect fluorescent antibody (IFA) assay. When the prevalence of Lyme disease is low as it is in many geographic areas, there is a much greater likelihood that a positive test result is from a person who does not have Lyme disease than from a person who does have the disease (a positive predictive value of <10%) . Thus, serology for Lyme disease should only be done when there are highly suggestive clinical findings. A diagnosis of Lyme disease should not be based on a positive EIA or IFA test result in the absence of suggestive clinical findings. A two-stage approach to the serodiagnosis is strongly recommended that includes EIA or IFA followed by an immunoblot assay for reactivity with specific B. burgdorferi antigens.

The EIA and IFA are the most widely used initial tests for Lyme disease. Multiple variations of these assays using different antigen preparations, techniques, and end points have been marketed. Results of the initial tests are generally reported as positive, negative, or indeterminate.

The immunoblot assay is generally performed to confirm results obtained by the EIA tests. Recombinant B. burgdorferi antigens or antigens from whole-cell lysates are electrophoretically separated, transferred to a nitrocellulose membrane, and reacted with a patient’s serum. Interpretation of the immunoblot is based on the number and molecular size of antibody reactions with the B. burgdorferi proteins. Blots can be analyzed for IgG or IgM. The antigen–antibody band pat terns on the immunoblots should be interpreted with knowledge of known results from patients at various stages of Lyme borreliosis, and caution should be used to avoid overinterpretation of minimally reactive blots.

مواضيع ذات صلة

The Growth Curve in Batch Culture

The Measurement of Microbial Concentrations

Bacterial Pathogenesis

Distribution of Normal Flora in The Body

Cultivation of Bacillus and Similar Organisms

Bacterial Cell wall

Bacillus cereus

Bacillus anthracis

Antimicrobial Susceptibility Testing and Therapy for Streptococcus,Enterococcus, and Similar Organisms

Serodiagnosis Of Streptococcus,Enterococcus, and Similar Organisms

Approach To Identification of Streptococcus, Enterococcus, and Similar Organisms

Criteria For Identification of Bacteria