The performances of seven Immulite 2000 (Siemens Healthcare Diagnostics) TORCH (Toxoplasma gondii, other microorganisms, rubella virus, cytomegalovirus, and herpes simplex virus) assays were evaluated in comparison with the performances of the ETI-MAX 3000 (DiaSorin) TORCH assays. The two systems demonstrated good agreement, and given their sensitivity, specificity, and positive predictive value, they can be used with confidence for TORCH prenatal screening.
Congenitally acquired infections can result in serious and debilitating sequelae. Prenatal screening for antibodies to the TORCH complex-Toxoplasma gondii, other microorganisms (e.g., Treponema pallidum), rubella virus (RV), cytomegalovirus (CMV), and herpes simplex virus (HSV)-is an important tool for identifying susceptible women, especially those with acute maternal infection, for whom early treatment is essential. Discriminating between primary and recurrent infection also is very important but often difficult (1-3).To facilitate the large workload that prenatal screening creates for the clinical laboratory, several automated random-access analyzers have been commercialized. The sensitivity and specificity of TORCH IgG and IgM assays on these systems vary, and manufacturers continue to reformulate assays to improve these characteristics. In our study, we evaluated the performance characteristics of seven TORCH assays (T. gondii, RV, and CMV IgG and IgM and HSV IgG) available on the Immulite 2000 immunoassay system (Siemens Healthcare Diagnostics Inc., Tarrytown, NY) and compared them to characteristics of the ETI-MAX 3000 TORCH assays (DiaSorin S. p. A., Saluggia, Vercelli, Italy), which are currently in use in our laboratory.This study was performed on sera (one sample/patient) prospectively collected consecutively from pregnant women referred to our microbiology laboratory for prenatal screening from September 2009 to March 2010. Approximately 500 total sera were tested for each analyte. Blood samples were clotted and centrifuged prior to testing. Results for sera analyzed using the Immulite 2000 system (IMM) were compared to TORCH assays on the ETI-MAX 3000 system (EMAX). IMM is an automated immunoassay analyzer with continuous random-access capabilities that uses enzyme-amplified chemiluminescence chemistry; EMAX is a fully automated enzyme immunoassay (EIA) microtiter plate analyzer with photometric measurement.IMM T. gondii IgG, RV IgG and IgM, CMV IgG, and HSV IgG assays are all 2-step, solid-phase, enzyme-enhanced immunoassays which have been described previously (4), whereas the T. gondii IgM and CMV IgM assays were recently reformulated and relicensed by Siemens. The T. gondii IgM assay employs a IgMcapture sandwich method, whereby patient IgM is captured by anti-IgM bound to the solid substrate. T. gondii IgM is then identified using a T. gondii IgM-specific antigen bound to the lightemitting agent alkaline phosphatase. The new Siemens T. gondii IgM assay uses P30 antigen as the capture antigen. This antigen has been shown to be well recognize...