Purpose
Acanthamoeba spp. keratitis (AK) is a severe and sight-threatening ocular infection, and diagnostic tools are needed to confirm AK. Diagnosis of AK by microscopic examination, culture, and polymerase chain reaction (PCR) has several limitations (sensitivity, specificity, rapidity, or necessity of advanced skills and special equipment). The aim of this work was to develop a rapid immunochromatographic (IC) test kit using fluorescent silica nanoparticle for detection of Acanthamoeba and confirm the efficacy for diagnosis of AK.
Methods
The IC kit consists of a test strip, extracted liquid, and fluorescent silica nanoparticle binding Acanthamoeba antibody. To perform a test, a sample treated with extracted liquid and fluorescent silica nanoparticle are mixed, the mixed liquid is delivered by drops at the edge of the test strip, and fluorescent emission is observed with a fluorescent scope for detection after 30 minutes reaction. The sensitivity in vitro was examined using diluted Acanthamoeba trophozoite and cysts, and the specificity in vitro was checked using pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans. Patients suspected AK were tested the IC kit and PCR amplifying Acanthamoeba DNA to detect the presence of Acanthamoeba in corneal scraping.
Results
The IC kit could detect at least 5 trophozoites and 40 cysts per sample, and did not show cross-reaction with other pathogens. Seven patients’ results were found to be positive by both the IC kit and PCR.
Conclusions
The IC test kit using fluorescent silica nanoparticle is sensitive and specific for detection of Acanthamoeba.
Keywords: 402 Acanthamoeba •
573 keratitis