Table 2.

Clinical Sensitivity of Borrelia burgdorferi Cell-free DNA Detection Combined with Acute-Phase 2-Tiered Serologic Testing in Patients With a Clinical Diagnosis of Erythema Migrans

	No. (%) Positive
Patients	B.b. cfDNA or CTTTa	B.b. cfDNA or MTTT Algorithm 1b	B.b. cfDNA or MTTT Algorithm 2c
All patients with suspected EM (N = 40)	24 (60)	28 (70)	28 (70)
Laboratory confirmed (n = 28)	22 (79)	24 (86)	24 (86)
Unconfirmed (n = 12d)	2 (17)	4 (33)	4 (33)

Abbreviations: B.b., Borrelia burgdorferi; cfDNA, cell-free DNA; CTTT, conventional 2-tiered testing; EM, erythema migrans; MTTT, modified 2-tiered testing.

^aSeropositivity by CTTT required a positive or equivocal whole-cell sonicate enzyme-linked immunosorbent assay (ELISA) (Zeus B. burgdorferi immunoglobulin G [IgG]/ immunoglobulin M [IgM] ELISA) and a positive IgM or IgG immunoblot (ViraStripe, Viramed AG). If only the IgM immunoblot was positive, the individual was considered CTTT seropositive only if symptoms were present for <1 month.

^bSeropositivity by MTTT algorithm 1 required a positive or equivocal result in both the Zeus B. burgdorferi IgG/IgM ELISA and the Immunetics/Oxford C6 Lyme ELISA.

^cSeropositivity by MTTT algorithm 2 required a positive or equivocal result in both the Zeus VlsE/pepC10 IgG/IgM ELISA and the Zeus B. burgdorferi IgG/IgM ELISA.

^dTwo skin cultures were contaminated with skin flora and were discontinued before the complete incubation period.