Evaluation of Rapid Diagnosis of Candidemia by Agglutination Test Using Gold Nanoparticles

Candidemia showed high morbidity and mortality and should be diagnosed immediately. The aim of this study was to provide a simple and rapid method for direct detection of Candida in the blood, using conjugated antibodies with gold nanoparticles by the agglutination method.

In this study, yeast species isolated from 40 blood samples of patients tested by the BACTEC method were used.  After identifying the etiologic agents by morphological and molecular methods, a mixture of yeast antigens was prepared. Briefly, a mixture of antigens was prepared from the Candida isolates detected from candidemia, and injected into healthy rabbit skin with complete adjuvant to produce antibodies. After injecting the incomplete adjuvant in four reminders, blood samples and serum were finally prepared from the rabbit. Antibody production and its efficacy were confirmed by ELISA method. Gold nanoparticles were chemically conjugated with antibodies. For rapid diagnosis of candidemia, the nanoparticle method was examined on the blood of four patients and blood contaminated with a certain number of Candida yeasts in the laboratory.

Candida albicans was the most common etiologic agent of candidemia, followed by Candida glabrata and Candida parapsilosis complex. In determining the cut-off nanoparticle method, the least yeast detectable in the patient's blood was one yeast. The sensitivity and specificity of the nanoparticle method for detecting Candida in the blood of four patients compared to blood culture was 100%.

Under our laboratory conditions, if testing 15 µl blood of a suspected patient to candidemia containing one yeast or even just Candida antigens exposed to 35 microliters of the nanoparticles conjugated antibodies, it shows agglutination during one minute.