Analytical comparison of 11 CE-IVD marked real-time PCR assays for Borrelia burgdorferi sensu lato detection

In some precise clinical manifestations of Lyme borreliosis, PCR can be helpful for diagnosis: suspicion of atypical erythema migrans, borrelial lymphocytoma, acrodermatitis chronica atrophicans, Lyme arthritis or in very early seronegative neuroborreliosis. This study aimed to evaluate: (1) the analytical sensitivity of commercial real-time PCR kits for Borrelia burgdorferi sensu lato (Bbsl), (2) their specificity, and (3) their practicability.

The performances of 11 CE-IVD marked commercial kits and the French NRC Borrelia's in-house PCR were evaluated. PCRs were performed blindly on quantified DNA extracts, from 14 Bbsl strains corresponding to eight different genospecies, and on DNAs from relapsing fever (RF) Borrelia, Treponema, Leptospira, and 26 other micro-organisms.

DNAs from Bbsl strains ranging from 10 to 10⁴ copies/5µL were detected by all the PCR kits evaluated, with the exception of B. spielmanii, which was not detected by one kit. Three kits had a higher limit of detection than the in-house PCR (P-value < 0.05). RF Borrelia generated positive PCR reactions for the majority of kits tested (9/11). The kits were generally easy to use, in terms of equipment, explanation of technical procedures, and realization in a laboratory competent in molecular microbiology whereas interpretation of results was moderately difficult to difficult to do for 9/11 kits.

This study shows that the analytical performance and practicability of the kits evaluated are broadly in line, but that advanced molecular biology skills are required to interpret the results. Simultaneous detection of Lyme Borreliosis and RF agents without precise distinction may result in a risk of confusion in the choice of biological matrices and in the wording of the result returned to the clinician. Diagnostic laboratories must pay particular attention to the amplification confirmation strategy.