FIG 1.

Schematic diagram illustrating the mCIM and eCIM. (A) A 1-µl loopful of test organism with suspected carbapenemase activity is resuspended in two tubes containing 2 ml of TSB. One tube is devoid of EDTA (mCIM), while the other is supplemented with EDTA (eCIM). (B) A meropenem disk (10 µg) is submerged in each tube, and the tubes are incubated without shaking at 35°C in ambient air for 4 h ± 15 min. (C) After 4 h, the disks are removed from the tubes and placed on Mueller-Hinton agar plates upon which a carbapenem-susceptible reporter strain (E. coli ATCC 25922) has been freshly applied. The plates are incubated at 35°C in ambient air for 18 to 24 h before the zone sizes are recorded. Note: in the absence of a positive mCIM result the eCIM result is not applicable.