This novel dipstick test has the potential to markedly improve early diagnosis of CM in many settings, enabling testing of urine in patients presenting to health care facilities in which lumbar puncture, or even blood sampling, is not feasible.

Cryptococcosis is a systemic infection caused by the pathogenic yeasts Cryptococcus neoformans and C. gattii. Detection of cryptococcal capsular antigen (CrAg) in serum and cerebrospinal fluid (CSF) plays an important diagnostic role. We prospectively compared the new Immuno-Mycologics Inc. (IMMY) lateral flow assay (LFA) and enzyme immunoassay (EIA) to our current CrAg test (Premier EIA; Meridian Bioscience Inc.). Discordant samples were retested with the latex-Cryptococcus antigen test (IMMY) and using serotype-specific monoclonal antibodies (MAbs). A total of 589 serum and 411 CSF specimens were tested in parallel. Qualitative agreement across assays was 97.7%. In all, 56 (41 serum and 15 CSF) samples were positive and 921 (527 serum and 394 CSF) samples were negative by all three assays. The 23 discrepant specimens were all Meridian EIA negative. Of 23 discordant specimens, 20 (87.0%) were positive by both the IMMY LFA and EIA, 2 were LFA positive only, and 1 was EIA positive only. Eleven discrepant specimens had adequate volume for latex agglutination (LA) testing; 8 were LA positive, and 3 were LA negative. LA-negative samples (2 CSF samples and 1 serum) had low IMMY LFA/EIA titers (<1:10). Serotype-specific MAb analysis of the LA-positive samples suggested that these specimens contained CrAg epitopes similar to those of serotype C strains. In conclusion, the IMMY assays showed excellent overall concordance with the Meridian EIA. Assay performance differences were related to issues of analytic sensitivity and possible serotype bias. Incomplete access to patient-level data combined with low specimen volumes limited our ability to fully resolve discrepant results. C ryptococcus spp. are encapsulated, yeast-like fungi that exist as saprobes in nature. Cryptococcosis, an invasive disease caused primarily by the pathogenic species Cryptococcus neoformans and C. gattii, is one of the most important opportunistic infections affecting immunocompromised patients worldwide. Immunoassays for the detection of cryptococcal capsular polysaccharide antigen (CrAg) in serum and cerebrospinal fluid (CSF) have played an integral role in the diagnosis of invasive disease since the first description of a latex agglutination assay nearly 50 years ago (1).A variety of different immunoassays are cleared by the U.S. Food and Drug Administration (FDA) for the diagnosis of cryptococcosis. These assays include latex agglutination (LA)-based tests, antigen capture sandwich enzyme immunoassays (EIAs), and a lateral flow immunochromatographic assay (LFA) (2-4). The antigen target for all tests is glucuronoxylomannan (GXM), the primary polysaccharide component of the cryptococcal capsule. GXM occurs as four major serotypes-A, B, C, and D-and a hybrid serotype, AD (5, 6). Serotypes A and D make up the large majority of C. neoformans clinical isolates. Serotype B and C isolates are classified as C. gattii based on biochemical and molecular genetic features that differentiate them from serotype A and D isolates (7).The sensitivities of four...

Dendritic cells (DC) can be divided into three subsets, Langerhans cells, myeloid DC (MDC), and lymphoid DC (LDC), based upon phenotypic and functional differences. We hypothesized that different DC subsets are associated with the development of protective vs nonprotective cell-mediated immune (CMI) responses against the fungal pathogen, Cryptococcus neoformans. To test this, mice were immunized with protective and/or nonprotective immunogens, and DC subsets in draining lymph nodes were assessed by flow cytometry. The protective immunogen (cryptococcal culture filtrate Ag-CFA), in contrast to the nonprotective immunogen (heat-killed cryptococci-CFA), the nonprotective immunogen mixed with the protective immunogen (cryptococcal culture filtrate Ag + heat-killed cryptococci-CFA), or controls, stimulated significant increases in total leukocytes, Langerhans cells, MDC, LDC, and activated CD4+ T cells in draining lymph nodes. The protective immune response resulted in significantly increased levels of anticryptococcal delayed-type hypersensitivity reactivity and activated CD4+ T cells at the delayed-type hypersensitivity reaction site. Draining lymph node LDC:MDC ratios induced by the protective immunogen were significantly lower than the ratios induced by either immunization in which the nonprotective immunogen was present. In contrast, mice given the nonprotective immunogen had LDC:MDC ratios similar to those of naive mice. Our data indicate that lymph node Langerhans cells and MDC are APC needed for induction of the protective response. The predominance of LDC in mice undergoing nonprotective responses suggests that lymph node LDC, like splenic LDC, are negative regulators of CMI responses. In addition to showing DC subsets associated with functional differences, our data suggest that the LDC:MDC balance, which can be modulated by the Ag, determines whether protective or nonprotective anticryptococcal CMI responses develop.

The prevalence of cryptococcal infection among advanced AIDS patients in the United States was high and above the published cost-effectiveness threshold for routine screening. We recommend routine CrAg screening among human immunodeficiency virus-infected patients with a CD4 count ≤100 cells/µL to detect and treat early infection.

Importance of field Cryptococcal meningitis is a leading cause of death globally among people with AIDS. In sub-Saharan Africa, cryptococcosis is estimated to kill more people than tuberculosis. Cryptococcosis is also an important infectious disease among immunosuppressed patients in countries with advanced medical care. Early diagnosis is the key to effective treatment, particularly in patients in resource-limited settings. A new lateral flow immunoassay (LFA) for cryptococcal antigen (CrAg) allows for rapid and inexpensive diagnosis of cryptococcosis at or near the point of patient contact. Areas covered This article reviews the need for improved diagnostics for cryptococcal meningitis and describes the features of an ideal diagnostic. The design of a new lateral flow immunoassay for CrAg is described as well as the results of initial clinical evaluation of the CrAg LFA. Expert opinion The CrAg LFA is recommended for use with serum, plasma or CSF for diagnosis of cryptococcal meningitis or non-meningeal cryptococcal disease in symptomatic patients. There is a need for further evaluation of LFA for screening of asymptomatic patients. However, the LFA is emerging as a valuable tool for screening of serum or plasma in ART-naïve adults with CD4 counts less than 100 cells/mm3 in geographic regions with a high prevalence of cryptococcal antigenemia. CrAg screening has the potential to identify patients with asymptomatic cryptococcal infection who should receive pre-emptive anti-fungal therapy.