Volume 20, Number 1—January 2014
Research
Multisite Validation of Cryptococcal Antigen Lateral Flow Assay and Quantification by Laser Thermal Contrast
David R. Boulware
, 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
, 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
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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