Production of 2-aminophenoxazin-3-one by Staphylococcus aureus causes false-positive results in β-galactosidase assays

Herman Tse; Elaine Chan; Ching Wan Lam; Ka Fai Leung; Pat Chow; Kim Chung Lee; Kong Hung Sze; Stanley K.K. Cheung; Man Kit Tse; Pak Leung Ho; Sze Pui Leung; Susanna K.P. Lau; Patrick C.Y. Woo; Kwok Yung Yuen

doi:10.1128/JCM.02299-12

Production of 2-aminophenoxazin-3-one by Staphylococcus aureus causes false-positive results in β-galactosidase assays

Herman Tse, Elaine Chan, Ching Wan Lam, Ka Fai Leung, Pat Chow, Kim Chung Lee, Kong Hung Sze, Stanley K.K. Cheung, Man Kit Tse, Pak Leung Ho, Sze Pui Leung, Susanna K.P. Lau, Patrick C.Y. Woo, Kwok Yung Yuen

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9 Citations (Scopus)

Abstract

Staphylococcus aureus can be distinguished from similar coagulase-positive staphylococci by its absence of β-galactosidase activity. This is commonly tested using o-nitrophenyl-β-D-galactopyranoside (ONPG) as the substrate. Unexpectedly, 111 and 58 of 123 isolates displayed apparent β-galactosidase activity in the ONPG assay and on the Vitek 2 system, respectively. Compositional analysis showed that the yellow coloration of the positive ONPG assay resulted from production of 2-aminophenoxazin-3-one. Alternative β-galactosidase substrates like X-Gal (5-bromo-4-chloro-3-indolyl-β-D- galactopyranoside) should be used for testing staphylococci.

Original language	English
Pages (from-to)	3780-3782
Number of pages	3
Journal	Journal of Clinical Microbiology
Volume	50
Issue number	11
DOIs	https://doi.org/10.1128/JCM.02299-12
Publication status	Published - Nov 2012
Externally published	Yes

ASJC Scopus Subject Areas

Microbiology (medical)

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Tse, H., Chan, E., Lam, C. W., Leung, K. F., Chow, P., Lee, K. C., Sze, K. H., Cheung, S. K. K., Tse, M. K., Ho, P. L., Leung, S. P., Lau, S. K. P., Woo, P. C. Y., & Yuen, K. Y. (2012). Production of 2-aminophenoxazin-3-one by Staphylococcus aureus causes false-positive results in β-galactosidase assays. Journal of Clinical Microbiology, 50(11), 3780-3782. https://doi.org/10.1128/JCM.02299-12

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title = "Production of 2-aminophenoxazin-3-one by Staphylococcus aureus causes false-positive results in β-galactosidase assays",

abstract = "Staphylococcus aureus can be distinguished from similar coagulase-positive staphylococci by its absence of β-galactosidase activity. This is commonly tested using o-nitrophenyl-β-D-galactopyranoside (ONPG) as the substrate. Unexpectedly, 111 and 58 of 123 isolates displayed apparent β-galactosidase activity in the ONPG assay and on the Vitek 2 system, respectively. Compositional analysis showed that the yellow coloration of the positive ONPG assay resulted from production of 2-aminophenoxazin-3-one. Alternative β-galactosidase substrates like X-Gal (5-bromo-4-chloro-3-indolyl-β-D- galactopyranoside) should be used for testing staphylococci.",

author = "Herman Tse and Elaine Chan and Lam, {Ching Wan} and Leung, {Ka Fai} and Pat Chow and Lee, {Kim Chung} and Sze, {Kong Hung} and Cheung, {Stanley K.K.} and Tse, {Man Kit} and Ho, {Pak Leung} and Leung, {Sze Pui} and Lau, {Susanna K.P.} and Woo, {Patrick C.Y.} and Yuen, {Kwok Yung}",

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doi = "10.1128/JCM.02299-12",

language = "English",

volume = "50",

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T1 - Production of 2-aminophenoxazin-3-one by Staphylococcus aureus causes false-positive results in β-galactosidase assays

AU - Tse, Herman

AU - Chan, Elaine

AU - Lam, Ching Wan

AU - Leung, Ka Fai

AU - Chow, Pat

AU - Lee, Kim Chung

AU - Sze, Kong Hung

AU - Cheung, Stanley K.K.

AU - Tse, Man Kit

AU - Ho, Pak Leung

AU - Leung, Sze Pui

AU - Lau, Susanna K.P.

AU - Woo, Patrick C.Y.

AU - Yuen, Kwok Yung

PY - 2012/11

Y1 - 2012/11

N2 - Staphylococcus aureus can be distinguished from similar coagulase-positive staphylococci by its absence of β-galactosidase activity. This is commonly tested using o-nitrophenyl-β-D-galactopyranoside (ONPG) as the substrate. Unexpectedly, 111 and 58 of 123 isolates displayed apparent β-galactosidase activity in the ONPG assay and on the Vitek 2 system, respectively. Compositional analysis showed that the yellow coloration of the positive ONPG assay resulted from production of 2-aminophenoxazin-3-one. Alternative β-galactosidase substrates like X-Gal (5-bromo-4-chloro-3-indolyl-β-D- galactopyranoside) should be used for testing staphylococci.

AB - Staphylococcus aureus can be distinguished from similar coagulase-positive staphylococci by its absence of β-galactosidase activity. This is commonly tested using o-nitrophenyl-β-D-galactopyranoside (ONPG) as the substrate. Unexpectedly, 111 and 58 of 123 isolates displayed apparent β-galactosidase activity in the ONPG assay and on the Vitek 2 system, respectively. Compositional analysis showed that the yellow coloration of the positive ONPG assay resulted from production of 2-aminophenoxazin-3-one. Alternative β-galactosidase substrates like X-Gal (5-bromo-4-chloro-3-indolyl-β-D- galactopyranoside) should be used for testing staphylococci.

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JO - Journal of Clinical Microbiology

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IS - 11

ER -

Production of 2-aminophenoxazin-3-one by Staphylococcus aureus causes false-positive results in β-galactosidase assays

Abstract

ASJC Scopus Subject Areas

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