Comparison of Conventional and Molecular Methods in Identification of Candida Species Isolated from Oropharyngeal Candidiasis

Candida species are normal flora in the human body and are the main cause of hospital infections in people with underlying disease. The purpose of the present study was comparison of the conventional and molecular laboratory methods in identifying different species of Candida to find the optimal method.

60 Candida isolates were obtained from oropharyngeal candidiasis patients and recognized using laboratory routine methods including germ tube production, culture on CHROMagar medium, API 20 C AUX kit and molecular ITS sequencing method. The concordances between the methods compared to the molecular method were measured by the kappa coefficient using SPSS 16.0 software.

Out of 60 Candida isolates, 10 isolates (16.6%) in germ tube formation test, 8 isolates (13.33%) in the API test, and 9 isolates (15%) in the culture on CHROMagar medium have different results in comparison to the ITS sequencing method. Germ tube (k= 0.90) and culture on CHROMagar medium methods (k= 0.66) showed the highest and the lowest agreement with the molecular method in the identification of Candida albicans species respectively.

The results showed that conventional methods alone cannot diagnose all Candida species and molecular methods such as ITS sequencing can be used to confirm the identification.