Improved Sensitivity of Lyme disease Western Blots Prepared with a Mixture of Borrelia Burgdorferi Strains 297 and B31

Testing for Borrelia burgdorferi (BB), the spirochetal agent of Lyme disease, is problematic due to poor sensitivity of commercially available serological tests. We evaluated an in-house Western Blot (WB) prepared with a mixture of two strains of BB, B31 and 297. Sensitivity and specificity of IgG and IgM testing using the two-strain WB was compared to testing with a commercial single-strain WB, and interpretation of the in-house WB using in-house criteria was compared to interpretation using criteria recommended by the Centers for Disease Control and Prevention (CDC). A total of 364 control and patient sera (including 88 from treated patients with confirmed Lyme disease) were tested. The sensitivity of the combined IgG and IgM commercial WB using CDC criteria was 77.1%. When the in-house IgG and IgM WB and CDC criteria were used, the combined sensitivity improved to 88.6%, while use of the in-house IgG and IgM WB and in-house interpretation criteria resulted in a combined sensitivity that increased to 97.1%. Using CDC criteria, the specificity of the in-house IgG and IgM WB was 100% and 97.1%, respectively; using in-house criteria; the specificity was 95.3% and 93.1% respectively. By removal of patients who reacted to band 31kDa but tested negative for antibodies to recombinant OspA antigen, in-house IgG and IgM WB specificity increased to >97%. Based on these results, we conclude that the use of the two-strain IgG and IgM WB and in-house interpretation criteria significantly increased the combined sensitivity of the test without significant loss of specificity. In patients with indeterminate WB results, a confirmation test with recombinant OspA is recommended.