Comparison of a Lateral Flow Assay and a Latex Agglutination
Cryptococcosis is major HIV-related opportunistic infections. Globally, nearly 1,000,000 morbidity of cryptococcal meningitis occur causing more than 600,000 of mortality every year. With regards to this, a rapid and reliable diagnostic tool is very useful for better management of cryptococcal patients.
In this study, the performance between Crypto Antigen Lateral Flow Kit (LFA) (IMMY) and latex agglutination test (LAT) method was evaluated for detection of cryptococcal antigen. A total of 82 archived serum and cerebrospinal fluid (CSF) specimen were used in this retrospective study. We found that, 27 positive samples of LAT were all positive by LFA.
Therefore, LFA is 100% sensitive (95% confidence interval,CI). Thirty-four negative samples of LAT were all negative by LFA, giving rise to 100% specificity (95% CI) of LFA.
In order to access the agreement of the specimens for both tests, Kappa agreement (κ) was calculated. Of 59 sera, 25 (42%) were positive by LAT and LFA; none of 34 LAT-negative sera were LFA positive (κ = 1). Of 23 CSF, two (4%) was positive by LAT and LFA; none of 21 LAT-negative CSF was LFA positive (κ = 1). In summary, this study demonstrates that the LFA is 100% sensitive and specific, with a high level of agreement with LAT.
Furthermore, LFA fulfills the WHO’s A.S.S.U.R.E.D. criteria (affordable, sensitive, specific, user friendly, rapid/robust, equipment-free and delivered) for a diagnosis test kit. Thus, the Crypto Antigen Lateral Flow Kit (LFA) (IMMY) shows vast potential as a point-of-care test (POCT) for detection of cryptococcal antigen.