Research Centre for Infection and Immunity, Division of Clinical Sciences, St George's University of London, Cranmer Terrace, London SW17 0RE, United Kingdom; Desmond Tutu HIV Centre, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, South Africa; Infectious Diseases Unit, GF Jooste Hospital, Cape Town, South Africa; Department of Microbiology and Immunology, University of Nevada, School of Medicine, Reno, United States; Immuno-Mycologics, Norman, OK, United States; Institute of Infectious Diseases and Molecular Medicine, Department of Medicine, University of Cape Town, South Africa; Department of Medicine, Imperial College London, United Kingdom
Jarvis, J.N., Research Centre for Infection and Immunity, Division of Clinical Sciences, St George's University of London, Cranmer Terrace, London SW17 0RE, United Kingdom, Desmond Tutu HIV Centre, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, South Africa, Infectious Diseases Unit, GF Jooste Hospital, Cape Town, South Africa; Percival, A., Department of Microbiology and Immunology, University of Nevada, School of Medicine, Reno, United States; Bauman, S., Immuno-Mycologics, Norman, OK, United States; Pelfrey, J., Immuno-Mycologics, Norman, OK, United States; Meintjes, G., Infectious Diseases Unit, GF Jooste Hospital, Cape Town, South Africa, Institute of Infectious Diseases and Molecular Medicine, Department of Medicine, University of Cape Town, South Africa, Department of Medicine, Imperial College London, United Kingdom; Williams, G.N., Infectious Diseases Unit, GF Jooste Hospital, Cape Town, South Africa; Longley, N., Research Centre for Infection and Immunity, Division of Clinical Sciences, St George's University of London, Cranmer Terrace, London SW17 0RE, United Kingdom, Desmond Tutu HIV Centre, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, South Africa, Infectious Diseases Unit, GF Jooste Hospital, Cape Town, South Africa; Harrison, T.S., Research Centre for Infection and Immunity, Division of Clinical Sciences, St George's University of London, Cranmer Terrace, London SW17 0RE, United Kingdom; Kozel, T.R., Department of Microbiology and Immunology, University of Nevada, School of Medicine, Reno, United States
Background. Many deaths from cryptococcal meningitis (CM) may be preventable through early diagnosis and treatment. An inexpensive point-of-care (POC) assay for use with urine or a drop of blood would facilitate early diagnosis of cryptococcal infection in resource-limited settings. We compared cryptococcal antigen (CRAG) concentrations in plasma, serum, and urine from patients with CM, using an antigen-capture assay for glucuronoxylomannan (GXM) and a novel POC dipstick test. Methods. GXM concentrations were determined in paired serum, plasma, and urine from 62 patients with active or recent CM, using a quantitative sandwich enzyme-linked immunosorbent assay (ELISA). A dipstick lateral-flow assay developed using the same monoclonal antibodies for the sandwich ELISA was tested in parallel. Correlation coefficients were calculated using Spearman rank test. Results. All patients had detectable GXM in serum, plasma, and urine using the quantitative ELISA. Comparison of paired serum and plasma showed identical results. There were strong correlations between GXM levels in serum/urine (rs = 0.86; P <. 001) and plasma/urine (rs = 0.85; P <. 001). Levels of GXM were 22-fold lower in urine than in serum/plasma. The dipstick test was positive in serum, plasma, and urine in 61 of 62 patients. Dipstick titers correlated strongly with ELISA. Correlations between the methods were 0.93 (P <. 001) for serum, 0.94 (P <. 001) for plasma, and 0.94 (P <. 001) for urine. Conclusions. 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. © 2011 The Author Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved.