Rapid Identification of blaIMP-1 and blaIMP-6 by Multiplex Amplification Refractory Mutation System PCR

Dear Editor, Carbapenem-resistant Enterobacteriaceae have acquired carbapenemase genes [1], which differ substantially across countries [2]. Transferable carbapenemase IMP-type metallo-β-lactamases, particularly IMP-1 and IMP-6, are commonly identified in the clinical setting in Japan [3, 4] and exhibit different substrate specificity despite having a difference of only one amino acid (IMP-6: Ser214Gly). IMP-1 producers are more resistant to imipenem than to meropenem, whereas IMP-6 producers are more resistant to meropenem [5]. We previously found that the susceptibility rate of IMP-6-positive Escherichia coli was higher for imipenem than for meropenem [3]. Thus, IMP-6-producing isolates may be erroneously categorized as imipenem-susceptible, which could lead to treatment failure in patients. KCI Citation Count: 2