Identification of Cryptococcus antigen in human immunodeficiency virus-positive Turkish patients by using the Dynamiker® lateral flow assay.

ABSTRACT

Cryptococcus neoformans causes life-threatening meningoencephalitis, particularly in human immunodeficiency virus (HIV)-positive individuals with low CD4 levels (<100 cells/µL). Although the burden of cryptococcal meningoencephalitis (CM) in Turkey is low (0.13 cases per 100 000 persons), asymptomatic individuals at risk of cryptococcosis should be screened for antigenemia to prevent the disease and/or promote early CM diagnosis. A lateral flow assay (LFA) is used to detect Cryptococcus antigen (CrAg) in cerebrospinal fluid and serum. We determined Cryptococcus antigenemia prevalence in serum samples of HIV-positive and HIV-negative adult patients by using Dynamiker® CrAg-LFA, a point-of-care dipstick test. Patients' demographic data, CD4 count, HIV-RNA levels and anti-retroviral therapy status were recorded. CrAg was detected in 28 (11%) of 254 HIV-positive patients screened but not in 100 HIV-negative control individuals; a significant difference was observed in the CrAg-LFA positivity rate between HIV-positive and HIV-negative groups (x2  = 11.970; P < .05). In CrAg-positive patients, the median CD4 level was 666 cells/µL (115-1344 cells/µL), with a median viral load of 23 copies/mL (0-3.69 × 106  copies/mL). In HIV-positive CrAg-negative patients, the median CD4 level was 633 cells/µL (31-2953 cells/µL) and the median viral load was 12 copies/mL (0-1.95 × 106  copies/mL; P > .05). Results indicate that HIV-positive patients with both low (<200 cells/µL) and high (>200 cells/µL) CD4 counts should be screened for asymptomatic cryptococcal antigenemia. HIV-associated asymptomatic cryptococcosis is not uncommon in Turkey, which warrants systematic screening. Updated strategies for CM prevention among HIV-positive patients should be used even in non-endemic countries.