Comparison of ATB FUNGUS 2 and VITEK-2 Antifungal Susceptibility (AST-YS01) Tests for Candida Species Isolated from Blood Culture

Soon Deok Park; Young Uh; In Ho Jang; Kap Jun Yoon; Jong Hee Shin

doi:10.5145/KJCM.2010.13.3.114

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Park, Uh, Jang, Yoon, and Shin: Comparison of ATB FUNGUS 2 and VITEK-2 Antifungal Susceptibility (AST-YS01) Tests for Candida Species Isolated from Blood Culture

Original Article

Korean J Clin Microbiol 2010;13(3):114-120.

Published online: 21 September 2010

DOI: https://doi.org/10.5145/KJCM.2010.13.3.114

Comparison of ATB FUNGUS 2 and VITEK-2 Antifungal Susceptibility (AST-YS01) Tests for Candida Species Isolated from Blood Culture

Soon Deok Park¹, Young Uh¹, In Ho Jang¹, Kap Jun Yoon¹, Jong Hee Shin²

¹Department of Laboratory Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea

²Chonnam National University Medical School, Gwangju, Korea

Correspondence: Young Uh, Department of Laboratory Medicine, Wonju Christian Hospital, 162 Ilsan-dong, Wonju 220-701, Korea. (Tel) 82-33-741-1592, (Fax) 82-33-731-0506, (E-mail) u931018@yonsei.ac.kr

Received 22 January 2010 Revised 30 April 2010 Accepted 18 June 2010

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

The VITEK-2 yeast susceptibility test (AST-YS01; bioMérieux, Hazelwood, MO, USA) has recently been introduced as a fully automated, commercial antifungal susceptibility test system that determines MIC endpoints spectrophotometrically, thereby eliminating subjective errors. We compared the ATB FUNGUS 2 (bioMérieux) and VITEK-2 (AST-YS01) systems to the CLSI M27 method for susceptibility testing of Candida isolates.

Methods

We tested 59 Candida species that were isolated from blood cultures at Wonju Christian Hospital between September 2008 and August 2009. We compared MIC results for amphotericin B, flucytosine, fluconazole and voriconazole using the ATB FUNGUS 2 and VITEK-2 (AST-YS01) tests to those obtained by the CLSI M27 broth microdilution method.

Results

Within two-fold dilutions of MICs, the agreement of the ATB FUNGUS 2 and VITEK-2 (AST-YS01) tests with the CLSI method according to anti-fungal agents were: amphotericin B, 100% vs. 100% flucytosine, 100% vs. 100% fluconazole, 83.6% vs. 98.3% and voriconazole, 83.6% vs. 96.7%, respectively. The categorical discrepancies for fluconazole and voriconazole were 20.4% and 18.6% for ATB FUNGUS 2, and 6.8% and 0% for VITEK-2 (ASTYS01). There were no major errors for fluconazole and voriconazole in either ATB FUNGUS 2 or VITEK-2 (ASTYS01) tests.

Conclusion

The VITEK-2 system (AST-YS01) appears to be rapid and highly correlative with the CLSI method, suggesting that it is effective for antifungal susceptibility testing for Candida species in clinical settings.

Keywords: Antifungal susceptibility, Blood culture, Candida species, VITEK-2, ATB FUNGUS 2, CLSI

REFERENCES

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Table 1.

In vitro susceptibilities of 59 isolates of Candida spp. to amphotericin B, flucytosine, fluconazole and voriconazole as determined with the ATB FUNGUS 2 and VITEK-2 (AST-YS01) system, and by CLSI M27 BMD methods

Species (No. of isolates tested)	Antifungal agents	Test methods	MIC (μ g/mL)			EA (%)^∗
Species (No. of isolates tested)	Antifungal agents	Test methods	Range	50%	90%	EA (%)^∗
C. parapsilosis (25)	AMB	FUNGUS 2	0.5	0.5	0.5	100
	AMB	VITEK-2	≤0.25	≤0.25	≤0.25	100
	AMB	CLSI M27	0.5∼1	0.5	1
	5-FC	FUNGUS 2	4	4	4	100
	5-FC	VITEK-2	≤1	≤1	≤1	100
	5-FC	CLSI M27	≤1	≤1	≤1
	FCA	FUNGUS 2	1∼4	1	1	100
	FCA	VITEK-2	≤1∼2	≤1	2	100
	FCA	CLSI M27	≤1∼2	≤1	≤1
	VRC	FUNGUS 2	0.06	0.06	0.06	100
	VRC	VITEK-2	≤0.125	≤0.125	≤0.125	100
	VRC	CLSI M27	≤0.125	≤0.125	≤0.125
C. tropicalis (15)	AMB	FUNGUS 2	0.5∼1	0.5	1	100
	AMB	VITEK-2	≤0.125∼≤0.25	≤0.25	≤0.25	100
	AMB	CLSI M27	≤0.25∼0.5	0.5	0.5
	5-FC	FUNGUS 2	4	4	4	100
	5-FC	VITEK-2	≤1	≤1	≤1	100
	5-FC	CLSI M27	≤1	≤1	≤1
	FCA	FUNGUS 2	1∼128	1	1	66.7
	FCA	VITEK-2	≤1	≤1	≤1	100
	FCA	CLSI M27	≤1	≤1	≤1
	VRC	FUNGUS 2	0.06∼8	0.06	8	66.7
	VRC	VITEK-2	≤0.125	≤0.125	≤0.125	100
	VRC	CLSI M27	≤0.125	≤0.125	≤0.125
C. albicans (12)	AMB	FUNGUS 2	0.5	0.5	0.5	100
	AMB	VITEK-2	≤0.25	≤0.25	≤0.25	100
	AMB	CLSI M27	≤0.125∼1	0.5	1
	5-FC	FUNGUS 2	4∼16	4	4	100
	5-FC	VITEK-2	≤1∼≥64	≤1	≤1	100
	5-FC	CLSI M27	≤1∼≥64	≤1	≤1
	FCA	FUNGUS 2	1∼128	1	128	66.7
	FCA	VITEK-2	≤1∼8	≤1	8	100
	FCA	CLSI M27	≤1∼32	≤1	32
	VRC	FUNGUS 2	0.06∼8	0.06	8	58.3
	VRC	VITEK-2	≤0.125	≤0.125	≤0.125	91.7
	VRC	CLSI M27	≤0.125~1	≤0.125	1
C. glabrata (5)	AMB	FUNGUS 2	0.5	0.5	0.5	100
	AMB	VITEK-2	≤0.25	≤0.25	≤0.25	100
	AMB	CLSI M27	0.5∼1	1	1
	5-FC	FUNGUS 2	4	4	4	100
	5-FC	VITEK-2	≤1	≤1	≤1	100
	5-FC	CLSI M27	≤1	≤1	≤1
	FCA	FUNGUS 2	1∼128	1	2	40
	FCA	VITEK-2	8∼16	8	16	80
	FCA	CLSI M27	≤1∼16	1	8
	VRC	FUNGUS 2	0.06∼8	0.06	8	80
	VRC	VITEK-2	≤0.125∼1	0.25	1	80
	VRC	CLSI M27	≤0.125∼0.25	≤0.125	0.25
C. haemulonii (2)	AMB	FUNGUS 2	0.5	0.5	0.5	100
	AMB	VITEK-2	≤0.25	≤0.25	≤0.25	100
	AMB	CLSI M27	0.5	0.5	0.5
	5-FC	FUNGUS 2	16	16	16	100
	5-FC	VITEK-2	≥64	≥64	≥64	100
	5-FC	CLSI M27	≥64	≥64	≥64
	FCA	FUNGUS 2	1	1	1	100
	FCA	VITEK-2	2	2	2	100
	FCA	CLSI M27	2	2	2
	VRC	FUNGUS 2	0.06	0.06	0.06	100
	VRC	VITEK-2	≤0.125	≤0.125	≤0.125	100
	VRC	CLSI M27	≤0.125	≤0.125	≤0.125
Total (59)	AMB	FUNGUS 2	0.5∼1	0.5	1	100
	AMB	VITEK-2	≤0.125∼≤0.25	≤0.25	≤0.25	100
	AMB	CLSI M27	≤0.125∼1	1	1
	5-FC	FUNGUS 2	4∼16	4	4	100
	5-FC	VITEK-2	≤1∼≥64	≤1	≤1	100
	5-FC	CLSI M27	≤1∼≥64	≤1	≤1
	FCA	FUNGUS 2	1∼128	1	128	83.6
	FCA	VITEK-2	≤1∼16	≤1	8	98.3
	FCA	CLSI M27	≤1∼32	≤1	8
	VRC	FUNGUS 2	0.06∼8	0.06	8	83.6
	VRC	VITEK-2	≤0.125∼1	≤0.125	≤0.125	96.7
	VRC	CLSI M27	≤0.125∼1	≤0.125	≤0.125

^∗ EA (Essential agreement, ±2log₂ dilutions) between commercial antifungal tests and CLSI M27 MICs. Abbreviations: BMD, broth microdilution method; AMB, amphotericin B; 5-FC, flucytosine; FCA, fluconazole; VRC, voriconazole.

Table 2.

Categorical agreement of flucytosine, fluconazole and voriconazole MICs determined by two commercial antifungal tests and CLSI M27 BMD method for 59 isolates of Candida spp.

Species (No. of isolates tested)	Antifungal agents	Test methods	CA (%)	(%) error
Species (No. of isolates tested)	Antifungal agents	Test methods	CA (%)	VME	ME	Minor
C. parapsilosis (25)	5-FC	FUNGUS 2	100	0	0	0
	5-FC	VITEK-2	100	0	0	0
	FCA	FUNGUS 2	100	0	0	0
	FCA	VITEK-2	100	0	0	0
	VRC	FUNGUS 2	100	0	0	0
	VRC	VITEK-2	100	0	0	0
C. tropicalis (15)	5-FC	FUNGUS 2	100	0	0	0
	5-FC	VITEK-2	100	0	0	0
	FCA	FUNGUS 2	66.7	33.3	0	0
	FCA	VITEK-2	100	0	0	0
	VRC	FUNGUS 2	66.7	33.3	0	0
	VRC	VITEK-2	100	0	0	0
C. albicans (12)	5-FC	FUNGUS 2	83.3	0	0	16.7
	5-FC	VITEK-2	100	0	0	0
	FCA	FUNGUS 2	50	25	0	25
	FCA	VITEK-2	83.3	0	0	16.7
	VRC	FUNGUS 2	58.3	41.7	0	0
	VRC	VITEK-2	100	0	0	0
C. glabrata (5)	5-FC	FUNGUS 2	100	0	0	0
	5-FC	VITEK-2	100	0	0	0
	FCA	FUNGUS 2	80	0	0	20
	FCA	VITEK-2	80	0	0	20
	VRC	FUNGUS 2	80	20	0	0
	VRC	VITEK-2	100	0	0	0
C. haemulonii (2)	5-FC	FUNGUS 2	0	0	0	100
	5-FC	VITEK-2	100	0	0	0
	FCA	FUNGUS 2	100	0	0	0
	FCA	VITEK-2	100	0	0	0
	VRC	FUNGUS 2	100	0	0	0
	VRC	VITEK-2	100	0	0	0
Total (59)	5-FC	FUNGUS 2	94.9	0	0	5.1
	5-FC	VITEK-2	100	0	0	0
	FCA	FUNGUS 2	79.6	13.6	0	6.8
	FCA	VITEK-2	93.2	0	0	6.8
	VRC	FUNGUS 2	81.4	18.6	0	0
	VRC	VITEK-2	100	0	0	0

Abbreviations: CA, categorical agreement; VME, very major error; ME, major error; Minor, minor error. Other Abbreviations: See Table 1.

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