Cryptococcal meningitis is a leading cause of meningitis in sub-Saharan Africa. Given the need for rapid point-of-care testing, we evaluated the diagnostic performance of the Dynamiker cryptococcal antigen (CrAg) lateral flow assay (LFA). We assessed the diagnostic performance of the Dynamiker CrAg LFA compared to the IMMY CrAg LFA as the reference standard. We tested 150 serum, 115 plasma, and 100 cerebrospinal fluid (CSF) samples from HIV patients with symptomatic meningitis and 113 serum samples from patients with suspected asymptomatic cryptococcal antigenemia. Compared to the IMMY CrAg LFA, sensitivity of Dynamiker CrAg LFA was 98% in serum, 100% in plasma, 100% in CSF from symptomatic patients and 96% in serum from asymptomatic patients. Specificity was 66% in serum, 61% in plasma, and 91% in CSF from symptomatic patients, and 86% in serum from asymptomatic patients. The positive predictive value was 85% in serum, 82% in plasma, and 96% in CSF from symptomatic patients, and 69% in serum from asymptomatic patients. The negative predictive value was 94% in serum, 100% in plasma, and 100% in CSF from symptomatic patients, and 99% in serum from asymptomatic patients. The interassay reproducibility was 100% across the four sample types with no observed discordant results when Dynamiker CrAg LFA was tested in duplicate. However, a high number of false positives were observed on serum of symptomatic patients (11%), serum of asymptomatic patients (11%) and plasma of symptomatic patients (14%). The Dynamiker CrAg LFA had excellent sensitivity but poor specificity, particularly when tested on serum and plasma.
Bibliographical noteFunding Information:
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Support for the parent study was from National Institute of Neurologic Disorders and Stroke (R01NS086312), the Fogarty International Center (K01TW010268, J.R.). R.K. and D.B.M. are supported through DELTAS Africa Initiative grant no. DEL-15-011 to THRiVE-2, Wellcome Trust grant no. 107742/Z/15/Z, and the United Kingdom government.
We are grateful for institutional support from the Infectious Diseases Institute. We also thank the entire meningitis team for patient care. The Dynamiker CrAg LFA kits were provided freely by Dynamiker Biotechnology (Tianjin) Co., Ltd.
© 2021 American Society for Microbiology. All Rights Reserved.
- Diagnostic techniques
- Point-of-care systems