A novel Borrelia-specific real-time PCR assay is not suitable for diagnosing Lyme neuroborreliosis.

BACKGROUND

Diagnosing Lyme neuroborreliosis (LNB) is complicated by a lack of adequate test systems and by the complex culturing conditions required to grow the causative pathogens in the Borrelia sensu lato complex. Improved testing methods are urgently needed. Here, we evaluate the applicability of a novel commercially available Borrelia-specific real-time PCR assay to diagnose LNB.

MATERIALS AND

METHODS

The specificity and sensitivity of the novel alphaCube Borrelia real-time PCR assay (Mikrogen) and the well-tested Micro-Dx™ real-time PCR assay (Molzym) were evaluated in cerebrospinal fluid (CSF) spiked with known amounts of Borrelia garinii and CSF from 19 patients with definite or possible LNB. CSF from patients diagnosed with neurosyphilis or enterovirus meningitis served as controls.

RESULTS

The alphaCube assay specifically identified Borrelia down to 93 B garinii cells/mL in spiked CSF samples. The Micro-Dx™ real-time PCR assay was able to identify the presence of bacteria down to 9300 cells/mL in spiked samples. In CSF from patients diagnosed with LNB the sensitivity of the alphaCube assay was 0.00 and 0.00 for the Micro-DX.

CONCLUSION

Although the alphaCube Borrelia assay was able to identify down to 93 cells/mL in spiked CSF samples, the inability to identify Borrelia in CSF samples from patients with LNB suggests that this type of infection carries a bacterial load in CSF below this detection level. Based on these results, neither the alphaCube Borrelia real-time PCR assay nor the Micro-Dx™ real-time PCR assay can be recommended for routine diagnostics of LNB using CSF samples.