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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)

Main Article

Table 4

Characteristics of CSF specimens positive only by cryptococcal antigen lateral flow immunochromatographic assay, Uganda and South Africa*

Cohort CSF LFA titer Serum CRAG LFA titer Serum CRAG latex titer Urine LFA result Classification Patient outcome
2006–2009 2 NA NA NA LFA false positive Unknown

LFA false positive
2010–2012 2 512 1:8 Cryptococcal meningitis Began ART; CSF culture-positive result; meningitis developed 6 weeks later
± 2,048 2,048 Cryptococcal meningitis Died after hospital discharge
± 32 + Cryptococcal meningitis Died in hospital
250 4 + Cryptococcal meningitis Began ART; minimum CD4 cell count 130 cells/μL
8 8 128 Cryptococcal meningitis Died after hospital discharge
±/16† 4,096 2,048 + Cryptococcal meningitis Given fluconazole, 800 mg/d; seizure; died; cryptococcoma mass identified postmortem

*CSF, cerebrospinal fluid; CRAG, cryptococcal antigen; LFA, lateral flow immunochromatographic assay; –, negative’ NA, not available; ART, antiretroviral therapy; ±, discordant readings by 2 independent readers; +, positive. All test results for CSF culture, India ink microscopy, and CSF CRAG latex were negative.
†Fresh specimen was CRAG latex and LFA negative. CRAG LFA titer of 16 on cryopreserved specimen. Repeat CSF testing results 2 weeks later for neurologic deterioration were positive and remained CRAG latex negative. Thermal contrast showed that all LFA strips had positive results with readings above background.

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