N. dengue disease IgM screening. For both assays, indices of 0.90 were considered negative, indices from 0.90 to 1 1.10 were considered equivocal, and indices LRP2 of 1.10 were considered positive. Table ?Table22 demonstrates the relationship between testing ELISA indices and the proportion of samples positive in the BS ELISA. Of the 592 sera with indices of 3.00 in the screening ELISA, 587 (99%) were positive in the BS ELISA. All 427 sera with indices of 6.00 in the screening ELISA were positive in the BS ELISA. TABLE 2. Relationship of dengue disease IgM BS ELISA results to screening ELISA Cephalexin monohydrate index ideals thead th colspan=”1″ rowspan=”2″ align=”center” valign=”middle” Display ELISA index /th th colspan=”1″ rowspan=”2″ align=”center” valign=”middle” Total no. of samples /th th colspan=”3″ rowspan=”1″ align=”center” valign=”bottom” No. (%) of samples with indicated BS ELISA result hr / /th th colspan=”1″ rowspan=”1″ align=”center” valign=”bottom” Bad /th th colspan=”1″ rowspan=”1″ align=”center” valign=”bottom” Equivocal /th th colspan=”1″ rowspan=”1″ align=”center” valign=”bottom” Positive /th /thead 0.90-1.109374 (80)13 (14)6 (6)1.11-2.0018066 (37)22 (12)92 (51)2.01-3.00899 (10)2 (2)78 (88)3.01-4.00532 Cephalexin monohydrate (4)0 (0)51 (96)4.01-5.00542 (4)0 (0)52 (96)5.01-6.00581 (2)0 (0)57 (98)6.01-8.00970 (0)0 (0)97 (100)8.01-10.001030 (0)0 (0)103 (100)10.01-14.001300 (0)0 (0)130 (100) 14.00970 (0)0 (0)97 (100)Total954154 (16)37 (4)763 (80) Open in a separate windowpane These findings demonstrate that Cephalexin monohydrate all sera with strong reactivity (index of 6.00) in the dengue disease IgM testing ELISA will also be positive in the BS ELISA; therefore, our dengue disease IgM screening algorithm can be modified to remove further screening of such sera in the BS ELISA. The application of this revised algorithm Cephalexin monohydrate to the current data set would have reduced the number of samples evaluated using the BS ELISA from 954 to 527, a reduction of 45%. If a laboratory’s quality assurance program allows an overall false-positive rate of 0.5%, the algorithm could be further modified to remove BS ELISA testing of sera with screening ELISA indices of 3.00; the application of this algorithm to the current data set would have reduced the number of samples tested by BS ELISA from 954 to 362 (a reduction of 62%), with only 5 of 2,692 sera (0.19%) exhibiting false-positive dengue virus IgM results. The BS approach for identifying false-positive reactivity is definitely routinely applied to additional screening -capture ELISA systems besides dengue disease IgM (e.g., Western Nile disease IgM) (8, 13). Therefore, it stands to reason that these additional screening assays, like the dengue disease IgM assay, may also have a characteristic high index slice point above which BS ELISA overall performance is not necessary. This slice point will undoubtedly vary among different assays, depending on the absorbance value of the screening ELISA calibrator and the dynamic range of the assay. Each laboratory must consequently define its own reflex screening algorithms for analytes measured by -capture ELISA. Footnotes ?Published ahead of printing on 18 June 2008. Referrals 1. Branch, S. L., and P. N. Levett. 1999. Evaluation of four methods for detection of immunoglobulin M antibodies to dengue disease. Clin. Diagn. Lab. Immunol. 6:555-557. [PMC free article] [PubMed] [Google Scholar] 2. Centers for Disease Control and Prevention. 2007. Weekly dengue surveillance statement. CDC Dengue Branch and Puerto Rico Division of Health. http://www.cdc.gov/ncidod/dvbid/dengue/documents/weeklyreport.pdf. Accessed 30 January 2008. 3. Chanama, S., S. Anantapreecha, A. A-nueggonpipat, Cephalexin monohydrate A. Sa-gnasang, I. Kurane, and P. Sawanpanyalert. 2004. Analysis of specific IgM reactions in secondary dengue disease infections: levels and positive rates in comparison with primary infections. J. Clin..
