Environmental samples were collected from sinks, drains, environmental services carts, and surfaces in rooms that housed affected patients and common areas of affected units. Samples were collected using Sponge-Sticks (3M, St. Paul, Minnesota) and EnviroMax Plus foam paddle swabs (Puritan Medical, Guilford, Maine), then processed as described previously [18 (link)]. Dilutions were plated onto CHROMagar KPC (DRG International, Springfield, NJ), Trypticase™ Soy Agar with 5% Sheep Blood (TSA II™, BD, Sparks, Maryland) and MacConkey II (BD, Sparks, Maryland), and cultured overnight at 35°C.
Environmental isolates were screened for antimicrobial resistance using 10 µg meropenem disks placed between the first and second quadrant of growth. Suspect colonies were selected within a 21 mm zone, then screened for Metallo-ß-lactamase (MBL) activity by comparing imipenem broth microdilution MICs in the presence (32 to 0.25 mg/ml) and absence (64 to 0.5 mg/ml) of metal chelators (0.2 mM EDTA and 0.02 mM phenanthroline). Resistance determinants were identified from cultured isolates by multiplex PCR for detection of blaOXA-48, blaVIM, blaNDM, and blaKPC [19 (link)].
Environmental isolates were screened for antimicrobial resistance using 10 µg meropenem disks placed between the first and second quadrant of growth. Suspect colonies were selected within a 21 mm zone, then screened for Metallo-ß-lactamase (MBL) activity by comparing imipenem broth microdilution MICs in the presence (32 to 0.25 mg/ml) and absence (64 to 0.5 mg/ml) of metal chelators (0.2 mM EDTA and 0.02 mM phenanthroline). Resistance determinants were identified from cultured isolates by multiplex PCR for detection of blaOXA-48, blaVIM, blaNDM, and blaKPC [19 (link)].
