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. 2003 Dec;41(12):5407–5413. doi: 10.1128/JCM.41.12.5407-5413.2003

FIG. 1.

FIG. 1.

Inhibition test for detection of MBL producers by use of SMA. Sample results of inhibition tests using SMA for detection of strains producing IMP-1, IMP-2, or VIM-2 type MBLs are shown. For MBL-producing strains, a clear expansion of the growth inhibition zone appears between the disks containing ceftazidime and SMA, respectively (A to C). In strains producing MBL as well as ESBLs or AmpC or CMY type cephalosporinases, the expansion of the growth inhibition zone is usually unclear. For such strains, the use of disks containing imipenem or meropenem instead of ceftazidime is recommended. By this substitution of disks, a clear growth inhibition zone appears between the disks containing imipenem and SMA, respectively (D). The MIC of imipenem or meropenem for MBL producers is sometimes lower than 32 μg/ml, but that of ceftazidime is usually higher than 64 μg/ml. Thus, disks containing 30 μg of ceftazidime are suitable for the first testing to detect MBL producers. IPM, imipenem; CAZ, ceftazidime.