Improvement of diagnostic approach to Lyme neuroborreliosis in children by using recombinant antigens in detection of intrathecally produced IgM/IgG

Background: The purpose of the study was to evaluate new 3rd-generation test kits, EIA Borrelia recombinant IgM and IgG (TestLine, Brno, Czech Republic), in serum and cerebrospinal fluid (CSF) of children with Lyme neuroborreliosis. Methods: Comparison of three tests was used: the whole-cell EIA from Borrelia garinii (EIA 1) was compared with the EIA using recombinant antigens (EIA 2) and immunoblot. In total, 364 samples of serum and CSF were examined. Eighty-six paired sera and CSF samples were evaluated in the first group of children with Lyme neuroborreliosis. The second group consisted of 30 children with probable Lyme neuroborreliosis. Sixty-six samples from children with neuroinfections other than borrelial etiology were used as controls. Results: In the first group of children with proven LNB, EIA 2 gave significantly more positive results for IgG in serum (P = 0.006; OR = 7.5) as in CSF (P < 0.001; OR = 4.5). There was no statistically significant difference in the IgM positivity of serum (P = 0.54; OR = 0.71). EIA 2 determined significantly (P = 0.001; OR = 0.06) less positive results of IgM in CSF in the LNB patients. IgG antibody index (AI) assessed by both methods revealed similar results (P = 0.646; OR = 1.38). Both methods are comparable, but IgM AI assessed by EIA 2 showed significantly less positive results (P < 0.001; OR = 0.04). The differences in the detection of positive IgM/IgG antibodies in serum and CSF did not reach statistical significance either in the groups of children with excluded LNB or in controls. Conclusions: EIA 2 showed better results than EIA 1 and western blot for the detection of positive IgG antibodies in serum and CSF. The difference in the calculation of AI IgG by EIA 1 and EIA 2 was not noticeable in the group of LNB patients. Comparing IgG and IgM AIs calculated from both tests, the sensitivity for EIA 2 was 68% for IgG and 26% for IgM. The specificity is 100% for both tests.