gDNA extraction from Candida albicans and Candida dubliniensis in subgingival samples in Argentina. Evaluation of different methods.

The oral cavity constitutes a unique ecosystem with highly variable ecological niches that harbor a great variety of microorganisms, including yeasts. Molecular methods are currently considered the gold standard for identifying species, although they involve limitations associated with the disruption of yeast cell walls to release the genomic DNA (gDNA) for amplification.

Aim: The aim of this study was to compare the performance of different methods for extracting gDNA from Candida albicans and Candida dubliniensis, subsequently amplifying DNA by PCR.

Materials and method: Fifty-two isolates (16 C. albicans and 36 C. dubliniensis) were obtained from subgingival biofilm of HIV+ patients with clinical signs of periodontal disease. The study evaluated 6 gDNA extraction methods and two PCR amplification methods. Furthermore, the presence of alleles of HWP1 gene was determined in C. albicans.

Results: Comparisons of six methods show statistically significant differences (p <0.001) except for C. albicans in two of them. For C. dubliniensis, statistical differences were observed in all comparisons. Commercial methods were more efficient for concentrating gDNA than in-house methods, and both PCRs were effective. Ten heterozygous C. albicans isolates for this allele were positive for the HWP1-1 / HWP1-2 allele, one was homozygous for Wild Type HWP1-1 allele, and 5 were homozygous for novel/rare HWP1-2 allele.

Conclusions: This study aims to provide simple, inexpensive strategies for phenotypic identification and molecular confirmation of Candida albicans and Candida dubliniensis for non-reference laboratories with low complexity and/or low budgets.