Evaluation of the Loop-Mediated Isothermal Amplification (LAMP) Technique in Swab Samples from Ulcerated Cutaneous Lesions Compared with Conventional Diagnostic Methods for American Tegumentary Leishmaniasis in Patients Treated at a Reference Center

Cutaneous leishmaniasis (CL) is a vector-borne disease caused by Leishmania spp. Molecular methods such as conventional PCR (cPCR) and real-time PCR (qPCR) show high accuracy but remain restricted to reference centers. Loop-mediated isothermal amplification (LAMP) enables rapid DNA amplification under isothermal conditions. LAMP targeting 18S rDNA using WarmStart® Colorimetric LAMP 2× Master Mix and Bst 2.0 DNA Polymerase with SYBR® Green I (BstSg) was evaluated in swab samples (extracted by kit—SW-kit and direct boil—SW-DB) and specimens collected through biopsy from ulcerated lesions of patients attending a reference center in Rio de Janeiro, Brazil. The reference standard was defined as at least one positive parasitological or molecular (cPCR) test plus clinical confirmation. Analytical sensitivity reached 10 fg with WS and 10 pg with BstSg. The diagnostic accuracy of LAMP ranged from 51.8% to 78.6%, with sensitivity from 52.5% to 81% and specificity from 39.6% to 89.4%. LAMP, particularly when applied to swab samples with DNA extracted using the SW-kit protocol and amplified with BstSg, showed promising diagnostic accuracy and operational feasibility as a less invasive approach for CL diagnosis, eliminating the need for skin biopsy and reducing patient discomfort during sample collection.