Borrelia burgdorferi - Host Immunity, Lab Diagnosis, AST, Treatment

Host Immunity of Borrelia burgdorferi

The earliest antibody response and development of IgM is observed in response to OspC membrane protein, flagellar Ag (FlaA dn FlaB), or the fibronectin-binding protein. IgM levels peak within several weeks but may be detectable for several months.

IgG response, as host immunity of Borrelia burgdorferi, develops slowly during the first several weeks of disease and increases with Ab responses to Osp17 and some additional proteins p39 and p58.

Laboratory diagnosis of Borrelia burgdorferi

Borrelia burgdorferi can be visualized and cultured although serology is the best method for diagnosis of Lyme’s disease. Laboratory diagnosis of Borrelia burgdorferi can be done by the presence of erythema migrans in the early stage of the disease.

Specimen

The specimen collected for laboratory diagnosis of Borrelia burgdorferi includes:

• peripheral blood

• biopsy

• CSF

• synovial fluids

Microscopy

The direct detection method for laboratory diagnosis of Borrelia burgdorferi is done by microscopy.

The number of spirochetes in the blood of patients with Lyne borreliosis is below the limits of microscopic detection. But it can be visualized in tissue sections stained with Warthin-Starry silver stain.

Culture

The culture of B. burgdorferi may be attempted.

Procedure

It is done by the procedure written below:

1. Specimen inoculated into a tube of modified Kelly’s medium

2. Incubated at 30-40°C for 12 weeks under microaerophilic condition

3. Blind subcultures (0.1ml) are performed from the lower portion of broth to fresh media

4. Cultures are examined by dark-field or fluorescence microscopy after staining with Acridine orange

Serodiagnosis

Serodiagnosis depends on the demonstration of specific Ab in the serum which persists for many years even after eradication of infection. The most commonly used tests are:

1. Indirect immunofluorescence assay (IFA)

2. ELISA (Enzyme-Linked Immunosorbent Assay)

3. Western blotting

* ELISA is used as a primary screening method. However, false-positive rates are high as a result of cross-reactivity.

* IFA is also used as a primary screening method. Specificity to IFA can be improved by adsorption of serum with Treponema phagedenis sonicate (IFA-ABS).

* Once, ELISA or IFA tests are positive, immunoblotting/Western blotting is done for confirmation.

Molecular diagnosis

PCR is used as a molecular diagnosis of Borrelia burgdorferi.

• PCR has detected Borrelia burgdorferi DNA in clinical specimens from patients with early and late stages of Lyme's disease.

• sensitivity and specificity of PCR depend on the specimen

AST of Borrelia burgdorferi

AST for Borrelia burgdorferi is generally not done

Treatment of Borrelia burgdorferi

Drugs of choice for treatment of Borrelia burgdorferi include:

• Parenteral cephalosporins

• 1st stage of Lyme disease:

  • Doxycycline

  • Amoxicillin

  • Cefuroxime

• If the initial treatment failed or later stages of the disease, then broad-spectrum cephalosporins such as:

  • Ceftriaxone

  • Cefotaxime

• usually given oral regimes and not IV therapy