Evaluation of BBL CHROMagar VanRE for Detection of Vancomycin-Resistant Enterococci in Rectal Swab Specimens

A study was performed on 517 surveillance rectal swabs to evaluate a selective and differential chromogenic medium, the BBL CHROMagar VanRE (CVRE), which enables recovery and identification of VanA- and VanB-containing Enterococcus faecium (ENFM) and Enterococcus faecalis (ENFS) isolates. Compared to BBL Enterococcosel agar, a bile-esculin-azide-vancomycin (BEAV) agar, the initial overall sensitivity, specificity, and positive and negative predictive values of CVRE for the detection of vancomycin-resistant ENFM and ENFS were 99.1% and 94.8% and 84.2% and 99.7%, respectively. Among our patient population, more vancomycin-resistant enterococci (VRE) were recovered with CVRE than BEAV.Vancomycin-resistant enterococci (VRE) are major causes of nosocomial infections in health care facilities, and those patients infected with VRE have worse outcomes while hospitalized (8). Rapid, reliable identification of these antibiotic-resistant organisms is crucial for patient management and infection control measures (9, 12).Culture from rectal swabs or stool specimens onto bile-esculin-azide agar with vancomycin (BEAV) is the VRE screening method used in many clinical laboratories. Confirmation of VRE using this medium requires 48 to 72 h. Chromogenic agars to detect VRE demonstrate promise (1-7, 10). BBL CHROMagar VanRE (CVRE; BD Diagnostics, Sparks, MD) is a selective and differential chromogenic agar under development for the detection of vancomycin-resistant E. faecium (VRENFM) and vancomycin-resistant Enterococcus faecalis (VRENFS). CVRE contains 8 μg/ml of vancomycin and uses chromogenic substrates to phenotypically differentiate VRENFM as mauve colonies and VRENFS as green colonies. Other bacteria are inhibited or typically grow as a color other than mauve or green. Our study compared the clinical performance of CVRE with that of BEAV for primary isolation and detection of VRE from surveillance rectal swabs.