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

Six decades of lateral flow immunoassay: from determining metabolic markers to diagnosing COVID-19

Technologies based on lateral flow immunoassay (LFIA), known in some countries of the world as immunochromatographic tests, have been successfully used for the last six decades in diagnostics of many diseases and conditions as they allow rapid detection of molecular ligands in biosubstrates. The popularity of these diagnostic platforms is constantly increasing in healthcare facilities, particularly those facing limited budgets and time, as well as in household use for individual health monitoring. The advantages of these low-cost devices over modern laboratory-based analyzers come from their availability, opportunity of rapid detection, and ease of use. The attractiveness of these portable diagnostic tools is associated primarily with their high analytical sensitivity and specificity, as well as with the easy visual readout of results. These qualities explain the growing popularity of LFIA in developing countries, when applied at small hospitals, in emergency situations where screening and monitoring health condition is crucially important, and as well as for self-testing of patients. These tools have passed the test of time, and now LFIA test systems are fully consistent with the world's modern concept of ‘point-of-care testing’, finding a wide range of applications not only in human medicine, but also in ecology, veterinary medicine, and agriculture. The extensive opportunities provided by LFIA contribute to the continuous development and improvement of this technology and to the creation of new-generation formats. This review will highlight the modern principles of design of the most widely used formats of test-systems for clinical laboratory diagnostics, summarize the main advantages and disadvantages of the method, as well as the current achievements and prospects of the LFIA technology. The latest innovations are aimed at improving the analytical performance of LFIA platforms for the diagnosis of bacterial and viral infections, including COVID-19.

Multicenter Cryptococcal Antigen Screening of HIV-Infected Patients in Iran

Early diagnosis and targeted preemptive antifungal treatment are crucial in reducing cryptococcal meningitis (CM)-related mortality in individuals living with human immunodeficiency virus (HIV). The present study was performed to determine cryptococcal antigenemia and outcomes among HIV-infected patients in Iran. This multicenter prospective study was conducted between October 2016 and December 2018. For the purpose of the study, blood samples were randomly collected from 177 profoundly immunosuppressed (CD4+ counts < 200 cells/µL) HIV-positive individuals in six major cities of Iran. The patients were antiretroviral therapy-naive or had received inadequate medication. The stored sera were screened for cryptococcal antigen (CrAg), using point-of-care lateral flow assay (IMMY® diagnostics, Norman, OK, US). Overall, out of the 174 asymptomatic patients, 3 (1.72%) cases were CrAg-positive using the LFA in serum. Accordingly, the prevalence of cryptococcal antigenemia was 7.14%, 0%, and 1.2% in the patients with the CD4+ counts of < 50, 50-100, and 100-200 cells/μL, respectively. The median age of the patients with antigenemia was 36 years (age range 8-55 years). The median CD4+ count of the cohort was 98 cells/μL (range 14-200 cells/μL). Routine screening of Iranian HIV-infected patients with CD4+ count of < 50 cells/µL before initiating antiretroviral therapy is justified. It is suggested to conduct more inclusive research throughout the whole country on more patients to recommend screening cryptococcal antigen strongly.

Identification of Mycoses in Developing Countries

Extensive advances in technology offer a vast variety of diagnostic methods that save time and costs, but identification of fungal species causing human infections remains challenging in developing countries. Since the echinocandins, antifungals widely used to treat invasive mycoses, are still unavailable in developing countries where a considerable number of problematic fungal species are present, rapid and reliable identification is of paramount importance. Unaffordability, large footprints, lack of skilled personnel, and high costs associated with maintenance and infrastructure are the main factors precluding the establishment of high-precision technologies that can replace inexpensive yet time-consuming and inaccurate phenotypic methods. In addition, point-of-care lateral flow assay tests are available for the diagnosis of Aspergillus and Cryptococcus and are highly relevant for developing countries. An Aspergillus galactomannan lateral flow assay is also now available. Real-time PCR remains difficult to standardize and is not widespread in countries with limited resources. Isothermal and conventional PCR-based amplification assays may be alternative solutions. The combination of real-time PCR and serological assays can significantly increase diagnostic efficiency. However, this approach is too expensive for medical institutions in developing countries. Further advances in next-generation sequencing and other innovative technologies such as clustered regularly interspaced short palindromic repeats (CRISPR)-based diagnostic tools may lead to efficient, alternate methods that can be used in point-of-care assays, which may supplement or replace some of the current technologies and improve the diagnostics of fungal infections in developing countries.