No abstract

We compared the performance of four assays for the detection of cryptococcal antigen in serum samples (n ‫؍‬ 634) and cerebrospinal fluid (CSF) samples (n ‫؍‬ 51). Compared to latex agglutination, the sensitivity and specificity of the Premier enzyme immunoassay (EIA), Alpha CrAg EIA, and CrAg lateral flow assay (LFA) were 55.6 and 100%, 100 and 99.7%, and 100 and 99.8%, respectively, from serum samples. There was 100% agreement among the four tests for CSF samples, with 18 samples testing positive by each of the assays.

We describe the first direct comparison of the reverse and traditional syphilis screening algorithms in a population with a low prevalence of syphilis. Among 1,000 patients tested, the results for 6 patients were falsely reactive by reverse screening, compared to none by traditional testing. However, reverse screening identified 2 patients with possible latent syphilis that were not detected by rapid plasma reagin (RPR).

The goal of this study was to evaluate the BioPlex 2200 Toxoplasma, rubella, and cytomegalovirus (CMV) Congenital infections caused by Toxoplasma gondii, rubella, and cytomegalovirus (CMV) are a significant cause of neonatal mortality and childhood morbidity worldwide (6,18,21). Due to their nonspecific clinical manifestations and the importance of early recognition of in utero infection, serologic screening for these pathogens has been considered a routine practice in many parts of the world (11). Conventional methods for the detection of antibodies to Toxoplasma, rubella, and CMV (ToRC) include immunofluorescence (IFA), enzyme immunoassay (EIA), and enzyme-linked fluorescent assay (ELFA). These techniques have been used for years in both diagnostic and screening protocols for ToRC infection and have demonstrated reliable performance (5,10,14,22). However, these methods have certain limitations, including low throughput, significant hands-on time, and in the case of IFA, a subjective interpretation of results.(Recently, multiplex flow immunoassay (MFI) technology emerged as a novel approach to assess the serologic response to various infectious diseases (3, 4, 13). This technology is similar to traditional EIA but allows for the simultaneous detection and identification of multiple analytes in a single reaction. MFI technology uses a liquid suspension array of up to 100 unique microspheres (5-to 6-m beads), each conjugated with a different capture molecule (e.g., antibody, antigen, nucleic acid). Each capture analyte is detected and quantitated following the addition of a fluorescently labeled reporter molecule (e.g., phycoerythrin) whose emission is measured by a flow-based detector. In 2009, Bio-Rad Laboratories (Hercules, CA) received FDA clearance for a ToRC IgG immunoassay based on MFI technology. In addition, Bio-Rad has developed a prototype ToRC IgM assay for use in cases of suspected acute infection. These assays are fully automated on the BioPlex 2200 automated analyzer (Bio-Rad Laboratories), allowing for a high-throughput analysis of the ToRC IgG and IgM class antibody response.Due to increasing test volumes (ϳ20% in the past 5 years) and the limitations of conventional methods (e.g., low throughput, increased hands-on time, and the requirement to aliquot samples prior to testing), we undertook a study to evaluate the BioPlex ToRC IgG and IgM immunoassays using clinical serum samples. The goal of this study was to compare the results of the BioPlex to routine testing by EIA/ELFA, using a third assay to arbitrate discordant results. MATERIALS AND METHODSStudy design. Prospective serum specimens (n ϭ 600) submitted to our reference laboratory for routine ToRC IgG and IgM testing by EIA (SeraQuest, Doral, FL; Diamedix, Miami, FL) or ELFA (Vidas; bioMérieux, Durham, NC) were also tested by the BioPlex ToRC IgM and IgG immunoassays using the BioPlex 2200 automated analyzer (Bio-Rad). Other specimen types, including cord blood samples, were not included in this evaluation. Specimens showing discordant res...

Due to the limited sensitivities of stool-based microscopy and/or culture techniques for Strongyloides stercoralis, the detection of antibodies to this intestinal nematode is relied upon as a surrogate for determining exposure status or making a diagnosis of S. stercoralis infection. Here, we evaluated three immunoassays, including the recently released InBios Strongy Detect IgG enzyme-linked immunosorbent assay (ELISA) (InBios International, Inc., Seattle, WA), the SciMedx Strongyloides serology microwell ELISA (SciMedx Corporation, Denville, NJ), and the luciferase immunoprecipitation system (LIPS) assay performed at the National Institutes of Health (NIH), for their detection of IgG antibodies to S. stercoralis. A total of 101 retrospective serum samples, previously submitted for routine S. stercoralis antibody detection using the SciMedx assay, were also evaluated by the InBios and LIPS assays. The qualitative results from each assay were compared using a Venn diagram analysis, to the consensus result among the three assays, and each ELISA was also evaluated using the LIPS assay as the reference standard. By Venn diagram analysis, 65% (66/101) of the samples demonstrated perfect agreement by all three assays. Also, the numbers of samples considered positive or negative by a single method were similar. Compared to the consensus result, the overall percent agreement of the InBios, SciMedx, and LIPS assays were comparable at 87.1%, 84.2%, and 89.1%, respectively. Finally, the two ELISAs performed analogously but demonstrated only moderate agreement (kappa coefficient for the two assays, 0.53) with the LIPS assay. Collectively, while the two commercially available ELISAs perform equivalently, neither should be used independently of clinical evaluation to diagnose strongyloidiasis.