False-Negative Serum Cryptococcal Antigen Lateral Flow Immunoassay Result for a Patient with Disseminated Cryptococcal Disease

Abstract

Cryptococcus neoformans (C. neoformans) is an opportunistic fungal pathogen to humans, which can be acquired from environmental sources. Its most important virulence factor is its polysaccharide capsule, which can be used for diagnostic tests that identify the cryptococcal antigen (CrAg). The CrAg lateral flow assay (LFA) is a dipstick immunochromatographic assay with high sensitivity and specificity; however, several false-negative cases have been reported. Here, we present a case of a false-negative serum CrAg LFA, in which the blood culture from a matched sample was positive for C. neoformans, thus demonstrating the postzone phenomenon.

Keywords:

• Cryptococcus neoformans
• lateral flow immunoassay
• postzone phenomenon

Ethics and Consent Statement

Because of the patient’s unstable state of consciousness, written informed consent was provided by the patient’s relative to allow the case details to be published, and our study was approved by the Ethics Committee at Jiangsu Province Hospital.

Disclosure

The authors declare that there have no conflicts of interest in this work.