title: Evaluation of a chromogenic medium supplemented with glucose for detecting Enterobacter sakazakii.
abstract: A commercial chromogenic agar medium (DFI) was supplemented with glucose (mDFI) to enhance the specificity of Enterobacter sakazakii (E. sakazakii) detection. Escherichia vulneris (E. vulneris), a putative false-positive strain on the DFI medium, produces alpha-glucosidase. The enzyme alpha- glucosidase hydrolyzes a substrate, 5-bromo-4-chloro-3- indolyl-alpha,D-glucopyranoside (XalphaGlc), producing green colonies. E. sakazakii strains produced green colonies on both DFI and mDFI agar, whereas E. vulneris produced green colonies on DFI agar but small white colonies on mDFI agar. E. sakazakii and E. vulneris were also readily differentiated by colony color when the mixed culture of the two strains was plated on mDFI agar and incubated for 24 h at 37 degrees C. The results indicate that the selectivity of the commercial chromogenic agar medium could be improved by a simple supplementation with glucose.
authors.affiliation: JIFSAN, University of Maryland, 0220 Symons Hall, College Park, Maryland, 20742, U.S.A.
authors.forename: Kwang-Young
authors.initials: KY
authors.lastname: Song
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Hyeon
authors.forename: Ho-Chul
authors.initials: HC
authors.lastname: Shin
authors.forename: Chan-Kyu
authors.initials: CK
authors.lastname: Park
authors.forename: In-Soo
authors.initials: IS
authors.lastname: Choi
authors.forename: Kun-Ho
authors.initials: KH
authors.lastname: Seo
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D002863:Chromogenic Compounds / Q000378:metabolism*; D044083:Cronobacter sakazakii / Q000166:cytology* / Q000302:isolation & purification* / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry*; D004925:Escherichia / Q000166:cytology / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D002863:Chromogenic Compounds; D003470:Culture Media; D000520:alpha-Glucosidases; D005947:Glucose