Glycopeptide Resistance in Gram-Positive Cocci: A Review

Table 1

The “Van Alphabet” (Phenotypes and Genotypes of vancomycin resistant enterococci).

Phenotype	Genotype (Gene clusters)	Vancomycin Resistance	Teicoplanin Resistance	Type of resistance
VanA [3] (commonly in E. faecalis and E. faecium)	vanA gene cluster	High-level resistance; MIC-64 μg/mL-≥1000 μg/mL	High-level resistance; MIC-16–512 μ/mL	High level inducible resistance
VanB [3] (commonly in E. faecalis and E. faecium)	vanB gene cluster	High-level resistance; MIC-4–512 μg/mL	Sensitive; MIC≤0.5 μg/mL	High level inducible resistance
VanC [3] (E. gallinarum, E. casseliflavus , E. flavescens)	vanC1, vanC2, vanC3 gene clusters	Low level resistance; MIC-2 μg/mL-32 μg/mL	Sensitive; MIC≤0.5 μg/mL	Low level constitutive resistance
VanD [4]	vanD gene cluster	Moderate-High level resistance; MIC-64–256 μg/mL	Low-level resistance; MIC-4–32 μg/mL	Inducible resistance
VanE [5]	vanE gene cluster	Low-level resistance; MIC-16 μg/mL	Sensitive; MIC-≤0.5 μg/mL	Inducible resistance
VanG [5]	vanG gene	Low level resistance; MIC ≤16 μg/mL	Sensitive; MIC≤0.5 μg/mL	Inducible resistance
VanL [6]	vanL gene cluster	Low level resistance; MIC-8 μ/mL	Sensitive	Inducible resistance
VanM [7]	vanM	High-level resistance; MIC>256 μg/mL	High level resistance	Inducible resistance
VanN [4]	vanN	Low-level resistance; MIC-16 μg/mL	Sensitive; MIC≤0.5 μg/mL	Constitutive resistance