Bacti-swabs (Remel, Lenexa, KS) were used by trained research personnel to obtain patient and environmental samples. Patients’ nares, oral cavity, groin, and perianal site swabs were cultured on bile-esculin plates with 6 mg/L vancomycin (BEV6) on the same day. Hands and environmental swabs (bed controls, side table top and bottom, nurse call button, curtain, toilet seat, door knob, TV remote control, wheelchair, and other equipment when available) were enriched overnight in Brain Heart Infusion broth at 36ºC before culturing on BEV6 plates. Growth suggestive of VRE was confirmed by pyrrolidonyl arylamidase testing (DrySlide; BD, Franklin Lakes, NJ).
Pulsed-field gel electrophoresis was performed to determine the relatedness of VRE isolates. Genomic deoxyribonucleic acid was prepared and digested with SmaI (New England BioLabs, Beverly, MA) using a previously described method [14 (link)]. SmaI fragments were separated using a CHEF DR III apparatus (Bio-Rad, Hercules, CA) and compared using BioNumerics software (Applied Maths, Kortrijk, Belgium). Similarity of isolates was calculated using Dice coefficient (BioNumerics software). Isolates were placed in the same pulsotype if their restriction patterns were ≥80% similar [14 (link)].
Pulsed-field gel electrophoresis was performed to determine the relatedness of VRE isolates. Genomic deoxyribonucleic acid was prepared and digested with SmaI (New England BioLabs, Beverly, MA) using a previously described method [14 (link)]. SmaI fragments were separated using a CHEF DR III apparatus (Bio-Rad, Hercules, CA) and compared using BioNumerics software (Applied Maths, Kortrijk, Belgium). Similarity of isolates was calculated using Dice coefficient (BioNumerics software). Isolates were placed in the same pulsotype if their restriction patterns were ≥80% similar [14 (link)].