Characterization of Presumptive Vancomycin-resistant Enterococci Recovered During Infection Control Surveillance in Dallas, Texas, USA

and are Gram-positive bacteria that normally inhabit the human gastrointestinal tract. They are also opportunistic pathogens and can cause nosocomial infection outbreaks. To prevent the spread of nosocomial infections, hospitals may rely on screening methods to identify patients colonized with multidrug-resistant organisms including vancomycin-resistant enterococci (VRE). Spectra VRE agar (Remel) contains vancomycin and other medium components that select for VRE and phenotypically differentiate between and by colony colour. We obtained 66 de-identified rectal swab cultures on Spectra VRE agar that were obtained during routine patient admission surveillance at a hospital system in Dallas, Texas, USA. We analysed 90 presumptive VRE from 61 of the Spectra VRE agar cultures using molecular and culture methods. Using typing, 55 were found to be and 32 were found to be . While most of the were positive for the gene by PCR (52 of 55 strains), few of the were positive for either or (five of 32 strains). The 27 - and -negative strains could not be recultured on Spectra VRE agar. Overall, we found that Spectra VRE agar performed robustly for the identification of vancomycin-resistant , but presumptive false positives were obtained for vancomycin-resistant .