Can glycopeptide-resistant enterococci be resistant to teicoplanin, but susceptible to vancomycin ?
No. There are no confirmed reports of this phenotype. GRE are always resistant to vancomycin. Cross-resistance to teicoplanin is shown by strains with VanA resistance (and very rare isolates with consitutively-expressed VanB resistance). However, there is a potential for laboratories to over-report teicoplanin resistance in enterococci. The interpretative zone diameters recommended by the British Society for Antimicrobial Chemotherapy (BSAC) for teicoplanin against enterococci require review. Current recommendations can result in incorrect reporting of teicoplanin-resistant, vancomycin-susceptible isolates (Potz & Livermore, unpublished data).
