P390 A lateral flow assay for the immunodiagnosis of human cat-transmitted Sporotrichosis

Abstract

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM Objectives Sporotrichosis is a neglected endemic implantation (subcutaneous) mycosis caused by different species of Sporothrix spp. Since the 1990s, cat-transmitted sporotrichosis (CTS) by Sporothrix brasiliensis has emerged as an important zoonosis in Brazil, being a public health issue. The disease continues to spread in the country and in neighboring countries. Therefore, the aim of the study is the validation of a fast and accurate test by Lateral Flow Assay (LFA) for serodiagnosis of CTS using human sera. Methods The anti-Sporothrix LFA was developed and provided by IMMY (Oklahoma, USA), and obtained via ConA purification of culture filtrate, composed by a 50:50 mix of S. schenkii (ATCC 58251), and S. brasiliensis (ATCC-MYA 4824). The control line was a goat anti-human IgG/IgM. The gold conjugate was a blend of proteins G and L. The strip uses a conjugate pad, nitrocellulose membrane, and an absorbent pad. A prospective cross-sectional study was performed with 300 human sera specimens divided into three groups: Group 1 (n = 100)—patients with a proven or probable diagnosis of CTS based on Guide to Health Surveillance from Ministry of Health Brazil; Group 2 (n = 100)—patients with other mycoses (implantation, systemic or opportunistic infections) confirmed in the laboratory by direct examination and/or culture and/or serological tests; Group 3 (n = 100)—asymptomatic volunteers (Fig. 1). Specimens were collected between November 2018 and March 2021 at the Mycology Laboratory of the Clinical Hospital Complex of the Federal University of Paraná, Curitiba, Brazil. The sera were diluted 1:441 with specimen diluent, 100 μL of the dilution dispensed into a flat bottom well, inserted strip, and incubated at room temperature (15-25°C) for 30 min. A visual read of the strips was done, this read was performed by two operators, within 10 min after the time of incubation. This study was approved by the Research Ethics Committee under registration CAAE 12379819.4.0000.0096. Data analysis was performed using MedCalc software. Results Using the IMMY's anti-Sporothrix detection antibody LFA, we observed a global sensitivity of 83% [95% confidence interval (CI) 74%-90%], a specificity of 82% (95% CI 76%-87%), positive predictive value of 69% (95% CI 62%-75%), negative predictive value of 90% (95% CI 85%-93%), and an accuracy of 82% (77%-86%). The results by clinical form and cross-reactivity analysis can be seen in Table 1. Conclusion These findings suggest that IMMY's anti-Sporothrix detection antibody LFA prototype is promising, can be a useful diagnostic tool for the diagnosis of CTS in human specimens, and can be used for the qualitative detection of serum antibodies against Sporothrix spp. Like other rapid tests, this LFA is faster and simpler to perform in comparison with other conventional laboratory assays for the diagnosis of sporotrichosis. This test can improve the evidence level of diagnosis of probable disease. Rapid detection of CTS reduces the morbimortality of the disease, and consequently the time of therapy. It could have an impact on the control of the outbreak.