Evaluation of Four Commercial IgG- and IgM-specific Enzyme Immunoassays for Detecting Mycoplasma pneumoniae Antibody: Comparison with Particle Agglutination Assay

Diagnosis of Mycoplasma pneumoniae infection is important due to its variable clinical manifestations and absence of response to beta-lactams. Introduction of enzyme immunoassays (EIAs) for serologic diagnosis of M. pneumoniae has made it possible to separate the analyses of specific IgG and IgM antibodies. We compared four different commercial EIAs, ImmunoWELL IgG, IgM (GenBio), Medac IgG, IgA, IgM (Medac), Platelia IgG, IgM (Sanofi Pasteur), and Ridascreen IgG, IgA, IgM (r-Biopharm) with indirect particle agglutination assay (PA), Serodia-MycoII (Fujirebio). We tested 91 specimens from 73 pediatric patients (2-17 yr) hospitalized at a tertiary-care hospital between December 2005 and January 2006. The measurements of IgM EIAs were correlated with PA titers (Spearman's correlation coefficient, from 0.89 to 0.92) with high concordance rates, ranging from 82.4% to 92.3%. However, some negative IgM-EIA results in PA-positive specimens indicated that serial samplings with convalescent sera would be necessary to confirm M. pneumoniae infection.

Comparison of 3 Automated Immunoassays for Hepatitis B Surface Antigen / 대한진단검사의학회지

BACKGROUND: Hepatitis B surface antigen (HBsAg) is one of the most important serological markers used to diagnose hepatitis B virus (HBV) infection. Automated immunoassays have been developed, meeting the current clinical requirement of HBsAg assays over the years. This study was performed to determine the degree of agreements between 3 kinds of HBsAg assay systems. METHODS: Serum samples from 425 patients were assayed by the HBsAg assay systems of Elecsys (Roche Diagnostics, Germany), ADVIA Centaur (Bayer Diagnostics, USA), and AxSYM (Abbott Laboratories, USA). RESULTS: The concordance rates among the 3 assays were 100%. A total of 249 (58.6%) specimens were positive, and their index values showed a weak correlation between the 3 assays; nevertheless, positive specimens with low levels (<10) of index values in one system also presented low values in other systems, and all of them were confirmed by neutralization assays. CONCLUSIONS: The 3 automated HBsAg assay systems presented a high level of concordance.

Comparison of Three Assay Systems for Qualitative and Quantitative Results of Hepatitis B Surface Antibody / 대한진단검사의학회지

BACKGROUND: With a technical improvement of the assay system, automated immunoassay analyzers for hepatitis B surface antibody (anti-HBs) are widely used. However, some discrepancies between assays are still being reported. We compared the qualitative and quantitative results of three kinds of anti-HBs assays. METHODS: Serum samples were collected from 517 patients and anti-HBs were determined using AxSYM AUSAB, Bayer ADVIA Centaur, and Roche Elecsys assay systems. RESULTS: The concordance rates between the three assays were 95.1% (543/571). The concordance rates were 97.7% between Centaur and Elecsys, 96.3% between AxSYM and Centaur, and 95.6% between AxSYM and Elecsys. Their correlation coefficients for quantitative results were 0.97, 0.94, and 0.93 in the same order. Twenty-eight specimens showed discrepant results, and all of them had antibody values below 31.5 mIU/mL. CONCLUSIONS: Three immunoassays for anti-HBs presented a high concordance and correlation; however, the results should be interpreted with caution, because there were still significant differences between assay methods, especially for a low-level of anti-HBs.