Design of species-specific primers for rapid detection and identification of Candida parapsilosis sensu stricto

Abstract

Candida species are the cause of approximately two million cases of candidiasis yearly worldwide, and are frequently involved in life-threatening infections. After Candida albicans, the Candida parapsilosis complex is the second most common cause of Candida infections, particularly in patients in intensive care units and in neonates. Contrary to many Candida species, C. parapsilosis sensu stricto is frequently present in water, and on surfaces made of plastic, rubber, and silicone, where it acts as aprimary coloniser for biofilm establishment. Identification methods for the C. parapsilosis complex include culture-dependent methods, MALDI-TOF, and multiplex PCR using ITS region, but remains amongst the most frequently misidentified species, due to the genetic similarity and lack of species-specific primers. In the present study, we developed novel species-specific primers for detection and identification of C. parapsilosis sensu stricto using locus CPAR2_105320, as template for easily accessible and widely used conventional PCR method. Using these primers, we successfully detected and identified C. parapsilosis sensu strictoin pure cultures isolated from clinical specimens and indoor environments. Additionally, this method enables detection of C. parapsilosis sensu stricto in biofilms and tap water samples from which DNA was extracted, and directly from suspensions of washed swab samples. All positive cases showed single clear band with 574 base pairs. Sequencing of the amplicon proved designed primers to be species-specific. In the future, primers can serve as a tool for rapid detection of C. parapsilosis sensustricto in the environment and clinical settings.