Evaluation of the four phenotypic methods for the speciation of Candida isolates in comparison with molecular method

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Original Article

Author Details : Reshma Bhaskaran*, Chithra Valsan, Sathivathy K A

Volume : 7, Issue : 2, Year : 2020

Article Page : 168-174

https://doi.org/10.18231/j.ijmr.2020.030

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Abstract

Background: The recent change in the epidemiology of Candidiasis with emergence of non albicans
Candida species as the predominant agents is of serious concern globally. Speciation of Candida is very
important since many of these species are associated with resistance to the common antifungal agents and
often lead to treatment failures. The existing conventional methods for speciation are time consuming and
tedious. We attempt to evaluate the performance of the four phenotypic methods for speciation of Candida
with molecular method.
Materials and Methods: This observational study was conducted on all the clinically significant isolates
of Candida species obtained from various specimens for a period of 2 years. Speciation was done by
phenotypic methods which include conventional germ tube test, chromogenic medium (HiCrome agar),
corn meal agar and automated method-Vitek-2 system. Molecular speciation was done by multiplex
polymerase chain reaction (PCR). Performance of phenotypic methods is evaluated with results of PCR
as gold standard.
Results: During the study period, a total of 80 isolates of Candida species from various clinical samples
were enrolled in the study. Molecular speciation identified 25 C.albicans (31.25%) which was the most
common species, followed by 23 C.tropicalis(28.75%), 13 C.parapsilosis (16.25%), 12 C.krusei (15%), 4
C.pelliculosa (5%), 2 C.auris (2.5%) and one C.glabrata (1.25%). Comparing with molecular method, the
sensitivity and specificity of chromogenic medium, corn meal agar and Vitek-2 compact system was found
to be 91.25% and 100%; 83.75% and 100% and both 100% respectively.
Interpretation and Conclusion: Overall non albicans Candida spp predominated in the present study.
Among the various phenotypic methods studied performance of HiCrome agar was very good and has the
advantage of speciation directly from samples where as that of Vitek 2 Compact was excellent and but
requires pure growth. Conventional methods failed to identify many species.

Keywords: Candida speciation, HiCrome agar, Non albicans Candida (NAC).

How to cite : Bhaskaran R , Valsan C , Sathivathy K A, Evaluation of the four phenotypic methods for the speciation of Candida isolates in comparison with molecular method. Indian J Microbiol Res 2020;7(2):168-174

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