Evaluation of D-xylose and 1% methyl-α-D-glucopyranoside fermentation tests for distinguishing Enterococcus gallinarum from Enterococcus faecium

• Published in: Journal of clinical microbiology Vol. 38; no. 10; pp. 3652 - 3655
• Main Authors: CHEN, D. K, PEARCE, L, MCGEER, A, LOW, D. E, WILLEY, B. M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.2000
• Subjects: a-Methylglucoside; Bacterial Proteins - genetics; Bacterial Typing Techniques; Bacteriological methods and techniques used in bacteriology; Bacteriology; Biological and medical sciences; Electrophoresis, Gel, Pulsed-Field; Enterococcus - classification; Enterococcus - genetics; Enterococcus - isolation & purification; Enterococcus faecium; Enterococcus faecium - classification; Enterococcus faecium - genetics; Enterococcus faecium - isolation & purification; Enterococcus gallinarum; False Positive Reactions; Fermentation; Fundamental and applied biological sciences. Psychology; Humans; methyl-^a-D-glucopyranoside; Methylglucosides - metabolism; Microbial Sensitivity Tests; Microbiology; Peptide Synthases - genetics; Sensitivity and Specificity; Teicoplanin - pharmacology; Vancomycin - pharmacology; Vancomycin Resistance; xylose; Xylose - metabolism; Performance evaluation; Xylose; Streptococcaceae; Enterococcus faecium; Enterococcus gallinarum; Rapid technique; Biochemical reaction; Bacteria; Micrococcales; Identification; Species specificity; Fermentation
• ISSN: 0095-1137; 1098-660X
• DOI: 10.1128/JCM.38.10.3652-3655.2000

To determine the validity of the rapid xylose and methyl-alpha-D-glucopyranoside (MDG) fermentation tests in distinguishing Enterococcus gallinarum from Enterococcus faecium, 156 well-characterized clinical isolates of enterococci (55 E. gallinarum, 91 E. faecium, and 10 Enterococcus faecalis isolates) known to be of different clones were examined in a blinded fashion. Species identification was confirmed by PCR of the ddl ligase genes of E. faecium and E. faecalis and the vanC1 gene of E. gallinarum. Xylose tests were performed with D-xylose tablets by using a heavy bacterial suspension and were interpreted after 2 h of incubation. Standard MDG fermentation tests were read after 24 h of incubation. The xylose fermentation test had a sensitivity of 98% (54 of 55) and a specificity of 99% (100 of 101) in distinguishing E. gallinarum from E. faecium and E. faecalis. The standard MDG test had a sensitivity of 100% (55 of 55) and a specificity of 95% (96 of 101) after 24 h. The xylose fermentation test is a simple method, easily incorporated into laboratory protocols, that distinguishes E. gallinarum from E. faecium with high sensitivity and specificity in 2 h. The standard MDG test has high sensitivity and can be useful in ruling out the presence of E. gallinarum but requires overnight incubation.