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Diagnostic accuracy of the Biosynex CryptoPS cryptococcal antigen semi-quantitative lateral flow assay in patients with advanced HIV disease.

Tenforde, MW; Boyer-Chammard, T; Muthoga, C; Tawe, L; Milton, T; Rulaganyang, I; Lechiile, K; Rukasha, I; Leeme, TB; Govender, NP; et al. Tenforde, MW; Boyer-Chammard, T; Muthoga, C; Tawe, L; Milton, T; Rulaganyang, I; Lechiile, K; Rukasha, I; Leeme, TB; Govender, NP; Ngidi, J; Mine, M; Molloy, SF; Harrison, TS; Lortholary, O; Jarvis, JN (2021) Diagnostic accuracy of the Biosynex CryptoPS cryptococcal antigen semi-quantitative lateral flow assay in patients with advanced HIV disease. J Clin Microbiol, 59 (1). e02307-20. ISSN 1098-660X https://doi.org/10.1128/JCM.02307-20
SGUL Authors: Harrison, Thomas Stephen

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Abstract

Background: High cryptococcal antigen (CrAg) titers in blood are associated with subclinical meningitis and mortality in CrAg-positive individuals with advanced HIV-disease (AHD). We evaluated a novel semi-quantitative lateral flow assay (LFA), CryptoPS, that may be able to identify individuals with high CrAg titers in a cohort of AHD patients undergoing CrAg screening.Methods: In a prospective cohort of patients with AHD (CD4 ≤200 cells/μL) receiving CD4 count testing, CryptoPS and IMMY LFA CrAg testing were performed on whole blood by two operators blinded to results of the other assay. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CryptoPS were assessed against IMMY LFA as a reference. CryptoPS low-titer (T1 band) and high-titer (T2 band) results were compared against IMMY LFA titers obtained through serial dilution.Results: 916 specimens were tested. Sensitivity of the CryptoPS assay was 61.0% (25/41, 95% confidence interval [95%CI]: 44.5-75.8), specificity 96.6% (845/875, 95%CI: 95.1-97.7), PPV 45.5% (95%CI: 32.0-59.4), and NPV 98.1% (95%CI: 97.0-98.9). All (16/16) CryptoPS false-negatives were samples with IMMY titers ≤1:160. Of 29 patients (30 specimens) who tested positive on CryptoPS but negative on IMMY LFA, none developed cryptococcal meningitis over 3-months follow-up without fluconazole. Median CrAg titers were 1:20 (interquartile range [IQR] 0-1:160) in CryptoPS T1-positive samples and 1:2560 (IQR 1:1280-1:10240) in T2-positives.Conclusions: Diagnostic accuracy of the CryptoPS assay was sub-optimal in the context of CrAg screening, with poor sensitivity at low CrAg titers. However, the CryptoPS assay reliably detected individuals with high titers associated with poor outcomes.

Item Type: Article
Additional Information: Copyright © 2020 Tenforde et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
Keywords: 06 Biological Sciences, 07 Agricultural and Veterinary Sciences, 11 Medical and Health Sciences, Microbiology
SGUL Research Institute / Research Centre: Academic Structure > Infection and Immunity Research Institute (INII)
Journal or Publication Title: J Clin Microbiol
ISSN: 1098-660X
Language: eng
Dates:
DateEvent
January 2021Published
21 October 2020Published Online
14 October 2020Accepted
Publisher License: Creative Commons: Attribution 4.0
Projects:
Project IDFunderFunder ID
P-2017-08-ST2-012National Institute for Health Researchhttp://dx.doi.org/10.13039/501100000272
P30AI045008National Institutes of Healthhttp://dx.doi.org/10.13039/100000002
T32AI007044National Institute of Allergy and Infectious Diseaseshttp://dx.doi.org/10.13039/100000060
F32AI140511National Institute of Allergy and Infectious Diseaseshttp://dx.doi.org/10.13039/100000060
950US Centers for Disease Control and PreventionUNSPECIFIED
212638Wellcome Trusthttp://dx.doi.org/10.13039/100004440
R01AI118511National Institute of Allergy and Infectious Diseaseshttp://dx.doi.org/10.13039/100000060
PubMed ID: 33087436
Go to PubMed abstract
URI: https://openaccess.sgul.ac.uk/id/eprint/112699
Publisher's version: https://doi.org/10.1128/JCM.02307-20

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