Performance of the BioPlex 2200 flow immunoassay in critical cases ofserodiagnosis of toxoplasmosis.

摘要

The BioPlex 2200 automated analyzer (Bio-Rad Laboratories, Hercules, CA) is arecently developed multiplex analyzer that enables the detection ofanti-Toxoplasma, -rubella, and -cytomegalovirus antibodies in the same assay. Theaim of this study was to compare this new technology (using the BioPlex 2200 ToRCIgG/IgM kit) in critical cases of serodiagnosis of toxoplasmosis (acute, chronic,or congenital infections and cases with discrepant results) to the technologiesused in our routine practice, i.e., the Platelia IgG/IgM enzyme-linkedimmunosorbent assays (ELISAs) (Bio-Rad Laboratories) and the Toxo-Screen directagglutination assay (bioMérieux, Lyon, France). Overall, most cases offalse-positive/negative results obtained with the Platelia IgG or Toxo-Screenassay were corrected by the BioPlex 2200 ToRC IgG (87.5%). Furthermore, theanalysis of 35 sequences of sera showed a trend toward a more rapid decrease ofIgM titers by BioPlex 2200 than by Platelia. These results for IgM detection can be explained by a weaker detection of residual IgM. Indeed, among 23 serumsamples from patients with probable past infection with long-lasting IgM(Platelia M positive and IgG avidity index, ≥0.5), the BioPlex 2200 ToxoplasmaIgM assay was positive for only 11 serum samples. In our panel of critical cases comprising 156 serum and 6 cord blood samples from 103 patients with acute,chronic, or congenital infection, the BioPlex 2200 IgG assay was a sensitive(97.8%) and specific (91.3%) method for IgG detection. The high specificity(97.4%) of IgM detection combined with the shorter kinetics of IgM titers mayconsiderably reduce the number of residual IgM detections, thus yielding moreprecise diagnoses of acute infections.