Performance Evaluation ofB. burgdorferi Serology Test Using Zeus Modified Two-Tier Testing (MTTT) Against Standard Two-Tier Testing (STTT) by Immunoblot Method

Abstract

Abstract Introduction/Objective Lyme disease (LD) is a multisystem infection caused by tick-transmitted spirochete Borrelia burgdorferi. Serologic testing of LD is the primary diagnostic approach, and two-tiered testing is required to optimize specificity. The FDA cleared a variation of standard two-tiered testing (STTT) known as modified two-tier testing (MTTT) replacing the second tier immunoblot testing with a second enzyme immunoassay either ELISA or chemiluminescence format that can detect IgM and IgG simultaneously (MTTT-1) or separately (MTTT-2). The objective of this study is to evaluate the MTTT-2 assay performance against the predicate immunoblot method. Methods/Case Report Positive and negative quality controls (QC) were used to perform within and between day precision. 96 serum specimens were screened using ZEUS ELISA Borrelia VlsE1/pepC10 IgG/IgM Test System followed by method comparison using ZEUS B. burgdorferi IgG and IgM, separate test systems (ZEUS scientific, Branchburg, NJ) with the predicate MarDX Lyme Western Blot kit on Biotech Trinblot analyzer (Trinity Biotech USA, Jamestown, NY). Interference study was performed using 17 serum samples: 4 HIV positive, 5 ANA positive with high titer, 2 EBV IgG positive, 1 CMV IgG positive, 2 EBV & CMV IgG positive, and 3 reactive syphilis samples. Patient clinical chart was reviewed on results that disagreed. Results (if a Case Study enter NA) Within and between day precision studies were acceptable. Method comparison between MTTT-2 vs. immunoblot demonstrated 73% agreement (70/96). The remaining 26 samples showed disagreement either by IgM or IgG alone, or both. Upon clinical chart review, 8/26 samples that disagreed were likely true positive and 3/26 samples were likely false positive by MTTT-2 assay; the remaining 15/26 samples either cannot be confirmed due to lack of clinical history or inappropriately ordered as routine test. No cross-reactivity was observed on the MTTT-2 assay. Conclusion Our study demonstrated MTTT-2 assay is equivalent or slightly better than the predicate immunoblot method, if ordered appropriately when clinically indicated.