Rapid differential diagnosis of vaginal infections using gold nanoparticles coated with specific antibodies

Vaginal infections caused by bacteria, Candida and Trichomonas vaginalis, affect millions of women annually worldwide. Symptoms and signs have limited value in differential diagnosis of three causes of vaginitis. Current laboratory methods for differential diagnosis are either expensive or time consuming. Therefore, in this work, development of a method based on gold nanoparticles has been investigated for rapid diagnosis of vaginal infections. Specific antibodies against three main causes of vaginal infections were raised in rabbits. The antibodies were then purified and conjugated to gold nanoparticles and used in an agglutination test for detection of vaginal infections. Finally, sensitivity and specificity of this test for diagnosis of vaginal infections were estimated using culture method as gold standard. Purification of antibodies from sera was confirmed by electrophoresis. Construction of nanoparticles was proved by TEM and FT-IR methods. Conjugation of antibodies to gold nanoparticles was confirmed using XPS method. Sensitivity and specificity of gold nanoparticles for diagnosis of Candida species were 100%, for Gardnerella were 100% and 93%, and for T. vaginalis was 53.3% and 100%, respectively. Gold nanoparticle-based method is a simple, rapid, accurate, and cost-effective test for differential laboratory diagnosis of vaginal infections.