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Volume 20, Number 1—January 2014

Multisite Validation of Cryptococcal Antigen Lateral Flow Assay and Quantification by Laser Thermal Contrast

David R. BoulwareComments to Author , Melissa A. Rolfes, Radha Rajasingham, Maximilian von Hohenberg, Zhenpeng Qin, Kabanda Taseera, Charlotte Schutz, Richard Kwizera, Elissa K. Butler, Graeme Meintjes, Conrad Muzoora, John C. Bischof, and David B. Meya
Author affiliations: University of Minnesota, Minneapolis, Minnesota, USA (D.R. Boulware, M.A. Rolfes, R. Rajasingham, M. von Hohenberg, Z. Qin, E.K. Butler, J.C. Bischof, D.B. Meya); Makerere University, Kampala, Uganda (R. Rajasingham, R.K. Kwizera, D.B. Meya); Mbarara University of Science and Technology, Mbarara, Uganda (K. Taseera, C. Muzoora); G.F. Jooste Hospital, Cape Town, South Africa (C. Schutz, G. Meintjes); University of Cape Town, Cape Town (C. Schutz, G. Meintjes)

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Table 2

Performance characteristics of cryptococcal diagnostic assays in persons with suspected meningitis, Uganda and South Africa*

Diagnostic test No. No. positive/no. tested (%)
Sensitivity Specificity PPV NPV
CRAG LFA 666 435/438 (99.3) 226/228 (99.1) 435/437 (99.5) 226/229 (98.7)
CSF culture† 806 459/510 (90.0) 296/296 (100.0) 459/459 (100.0) 296/347 (85.3)
100-μL volume 524 309/328 (94.2) 196/196 (100.0) 309/309 (100.0) 196/215 (91.2)
10-μL volume 282 150/182 (82.4) 100/100 (100.0) 150/150 (100.0) 100/132 (75.8)
India ink microscopy 805 438/509 (86.1) 288/296 (97.3) 438/446 (98.2) 288/359 (80.2)
CRAG latex (Meridian)‡ 279 176/180 (97.8) 85/99 (85.9) 176/190 (92.6) 85/89 (95.5)
CRAG latex (Immy)§ 749 452/466 (97.0) 283/283 (100.0) 452/452 (100.0) 283/297 (95.3)

*PPV, positive predictive value; NPV, negative predictive value; CRAG, cryptococcal antigen: LFA, lateral flow immunochromatographic assay; CSF, cerebrospinal fluid. All samples tested by CSF CRAG LFA had false-positive results and did not have any other pathogen identified. However, serum or plasma samples were not available for testing for cryptococcal antigenemia to determine if the original result indicated enhanced detection.
†Two quantitative CSF culture procedures were used in 2006–2009 (input volume 10 μL) and 2010–2012 (input volume 100 μL).
‡Meridian, Cincinnati, OH, USA.
§Immy, Inc., Norman, OK, USA.

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Page created: January 03, 2014
Page updated: January 03, 2014
Page reviewed: January 03, 2014
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