[Metallo-beta-lactamase producing bacteria]

Abstract

Metallo-beta-lactamases are the carbapenemases belonging to the class B beta-lactamases on a molecular level. Two types of the metallo-beta-lactamase, IMP-1 and VIM-1, which have been detected mainly from Pseudomonas aeruginosa, respectively, in Japan and in Europe are especially important, because of the broad substrate specificity. These enzymes confer resistance to not only the carbapenems but also almost all beta-lactam antibiotics expect for monobactams. Clinical strains producing IMP-1 type enzymes are easily detectable by the PCR method or by the double-disk method using the enzyme inhibitor of mercapto-compound and the substrate antibiotic such as imipenem or ceftazidime. The gene blaIMP is frequently identified as a cassette inserted in the integron structure on the transmissible plasmids, disseminating among various gram-negative bacteria.