Comparison of VITEK 2 with ITS2-Fragment Length Polymorphism Analysis for Identification of Yeast Species

DOI: 10.1128/JCM.42.5.2209-2211.2004

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TABLE 1.

Identification results with ID32C, VITEK 2, and ITS2-FLP

Organism	No. of isolates	System	No. of isolates with the following result:				Final identification established by:
Organism	No. of isolates	System	Identified	Low discrimination	Misidentification	Unidentified	Final identification established by:
C. albicans	7	ID32C	6		1 (C. sake)		Green colonies on chromagar, morphology on cornmeal agar
		VITEK 2	7
		ITS2-FLP-I	7
		ITS2-FLP-BF	7
C. dubliniensis	1	ID32C	1
		VITEK 2		1			Weak growth at 42°C
		ITS2-FLP-I	1
		ITS2-FLP-BF	1
C. glabrata	18	ID32C	17	1			Pink colonies on chromagar, no pseudohyphae on cornmeal agar, T + M−^a
		VITEK 2	5	4 (C. magnoliae)	3 (C. magnoliae)	5	Pink colonies on chromagar, no pseudohyphae on cornmeal agar, T + M−
				1 (C. colliculosa)
		ITS2-FLP-I	18
		ITS2-FLP-BF	16			2
C. guilliermondii	3	ID32C	3
		VITEK 2	3
		ITS2-FLP-I	3
		ITS2-FLP-BF	2			1
C. krusei	3	ID32C	3
		VITEK 2	1			2	Pink colonies on Chromagar plate
		ITS2-FLP-I	3
		ITS2-FLP-BF	3
C. parapsilosis	14	ID32C	14
		VITEK 2	12			2	Morphology on cornmeal agar
		ITS2-FLP-I	13		1 (Trichosporon mucoides)		Morphology on cornmeal agar^b
		ITS2-FLP-BF	13		1 (T. mucoides)		Morphology on cornmeal agar^b
C. tropicalis	3	ID32C	3
		VITEK 2	3
		ITS2-FLP-I	3
		ITS2-FLP-BF	3
C. neoformans	5	ID32C	5
		VITEK 2	5
		ITS2-FLP-I	5
		ITS2-FLP-BF	3			2
B. capitatus	2	ID32C	2
		VITEK 2	2
		ITS2-FLP-I	2
		ITS2-FLP-BF	2
S. cerevisae	4	ID32C	4
		VITEK 2	3	1 (C. colliculosa)			Purple colonies on chromagar, morphology on cornmeal agar
		ITS2-FLP-I	4
		ITS2-FLP-BF	4
C. palmioleophila	1	ID32C				1
		VITEK 2				1
		ITS2-FLP-I			1 (C. guilliermondii)		Sequencing^c
		ITS2-FLP-BF			1 (C. guilliermondii)		Sequencing^c
Total	61	ID32C	58		1	2
		VITEK 2	41	7	3	10
		ITS2-FLP-I	59		2
		ITS2-FLP-BF	55		2	4

↵ a T + M−, trehalose positive, maltose negative.
↵ b Due to a software problem this strain was misidentified. This problem has been resolved, and similar misidentifications are no longer possible.
↵ c C. palmioleophila and C. guilliermondii have identical ITS2 lengths (323 to 324 bp). Differentiation is possible by restriction with RsaI, which yields a 157-bp restriction fragment for C. guilliermondii and no restriction for C. palmioleophila.

TABLE 2.

VITEK 2 reactions leading to misidentification of the strains tested

No. of misidentified yeasts	Reference method	VITEK 2 identification	Possible cause of misidentification
1	S. cerevisiae	C. colliculosa	No assimilation of d-maltose
2	C. krusei	Unidentified	No cleavage of d-glucosidase-4MU
4	C. glabrata	C. magnoliae	Assimilation of d-mannitol and d-raffinose
5	C. glabrata	Unidentified	No assimilation of histidine arylamidase; extra assimilation test results were positive