IMP-type metallo-β-lactamases in Gram-negative bacilli: distribution, phylogeny, and association with integrons

Abstract

Twenty-nine IMP-type β-lactamases (IMPs) have been identified in at least 26 species of clinically important Gram-negative bacilli from more than 24 countries/regions. Most of bla_IMP genes are harbored by class 1 integrons that are usually embedded in transposons and/or plasmids, footnoting their horizontal transfer and worldwide distribution. bla_IMP genes usually co-exist with other resistance genes, such as aacA, catB, and bla_OXA, resulting in multi-drug resistance. Compared to other gene cassettes, 76.3% of the bla_IMP gene cassettes are located adjacent to Pc promoter of the class 1 integrons, indicating that the bla_IMP genes are readily expressed in most of bacterial hosts.

Keywords::

• Metallo-β-lactamases (MBLs)
• IMP-type β-lactamases (IMPs)
• integrons
• carbapenems
• Gram-negative bacilli