Recombinase Polymerase Amplification Assay with Lateral Flow Strips for Rapid Diagnosis of Candidiasis due to Candida parapsilosis

Background: Candida parapsilosis is a common cause of candidiasis among hospitalized patients, often surpassing Candida albicans . Due to the recent increase in C. parapsilosis infections, there is an urgent need for rapid, sensitive, and real-time on-site detection of nucleic acids for timely diagnosis of candidiasis. Methods We developed an assay for detection of C . parapsilosis by combining recombinase polymerase amplification (RPA) with a lateral flow strip (LFS). The RPA-LFS assay was used to amplify the beta-1,3-glucan synthase catalytic subunit 2 ( FSK2 ) gene of C. parapsilosis with a primer-probe set optimized by introducing base mismatches (4 bases modified by the probe and one by the reverse primer) to achieve specific and sensitive detection of clinical samples. Results The RPA assays can rapidly amplify and visualize a target gene within 30 min, while the entire process can be completed within 40 min by pre-processing the sample.The sensitivity and specificity of the RPA-LFS assay were determined by analysis of 35 common clinical pathogens and 281 clinical samples against quantitative PCR. Conclusions The results confirmed that the proposed RPA-LFS assay is a reliable molecular diagnostic method for the detection of C. parapsilosis to meet the urgent need for rapid, specific, sensitive, and portable field testing.