Performance of India ink and Acridine orange against culture.

<p>Performance of India ink and Acridine orange against culture.</p

<i>Cryptoccocus</i> yeasts stained with acridine orange and India ink.

<p>(a) Image of a positive acridine orange slide showing <i>Cryptococcus</i> yeasts fluorescing green against a dark background, using a blue filter on a fluorescent microscope. (b) Image of a negative acridine orange slide showing no <i>Cryptococcus</i> yeasts. (c) Image of a positive india ink slide showing a capsule of <i>Cryptococcus</i> yeasts on a bright field light microscope. (d) Image of a negative india ink slide showing no <i>Cryptococcus</i> yeasts. All images were taken at 40x magnification.</p

Venn diagram of the distribution of Cryptococcal meningitis CSF diagnostics.

<p>Distribution of 194 CSF samples from 96 cryptococcal meningitis cases. All samples were positive for CSF cryptococcal antigen lateral flow assay. Only 66% of the samples were positive for India ink, acridine orange and culture.</p

Baseline characteristics of the study population.

<p>Baseline characteristics of the study population.</p

Additional file 1: of Evaluation of trypan blue stain in a haemocytometer for rapid detection of cerebrospinal fluid sterility in HIV patients with cryptococcal meningitis

Study raw data. File contains a full set of raw data for the tests performed and baseline clinical and demographics characteristics. (XLSX 570 kb

Evaluation of a point-of-care immunoassay test kit ‘StrongStep’ for cryptococcal antigen detection

<div><p>Background</p><p>HIV-associated cryptococcal meningitis is the leading cause of adult meningitis in Sub-Saharan Africa, accounting for 15%–20% of AIDS-attributable mortality. The development of point-of-care assays has greatly improved the screening and diagnosis of cryptococcal disease. We evaluated a point-of-care immunoassay, StrongStep (Liming Bio, Nanjing, Jiangsu, China) lateral flow assay (LFA), for cryptococcal antigen (CrAg) detection in cerebrospinal fluid (CSF) and plasma.</p><p>Methods</p><p>We retrospectively tested 143 CSF and 77 plasma samples collected from HIV-seropositive individuals with suspected meningitis from 2012–2016 in Uganda. We prospectively tested 90 plasma samples collected from HIV-seropositive individuals with CD4 cell count <100 cells/μL from 2016–2017 as part of a cryptococcal antigenemia screening program. The StrongStep CrAg was tested against a composite reference standard of positive Immy CrAg LFA (Immy, Norman, OK, USA) or CSF culture with statistical comparison by McNemar’s test.</p><p>Results</p><p>StrongStep CrAg had a 98% (54/55) sensitivity and 90% (101/112) specificity in plasma (<i>P</i> = 0.009, versus reference standard). In CSF, the StrongStep CrAg had 100% (101/101) sensitivity and 98% (41/42) specificity (<i>P</i> = 0.99). Adjusting for the cryptococcal antigenemia prevalence of 9% in Uganda and average cryptococcal meningitis prevalence of 37% in Sub-Saharan Africa, the positive predictive value of the StrongStep CrAg was 50% in plasma and 96% in CSF.</p><p>Conclusions</p><p>We found the StrongStep CrAg LFA to be a sensitive assay, which unfortunately lacked specificity in plasma. In lower prevalence settings, a majority of positive results from blood would be expected to be false positives.</p></div

Semi-Quantitative titration of the StrongStep LFA as compared to the Immy LFA.

<p>Semi-Quantitative titration of the StrongStep LFA as compared to the Immy LFA.</p

Performance characteristics of the StrongStep LFA in Uganda.

<p>Performance characteristics of the StrongStep LFA in Uganda.</p

Characteristics of CSF and Plasma specimens misclassified by the StrongStep LFA.

<p>Characteristics of CSF and Plasma specimens misclassified by the StrongStep LFA.</p