Metallo β Lactamases Gene blaimp, blaspm and blavim Detection by Multiplex Real-Time TaqMan Assay on the Smartcycler
Gram-negative bacteria have a range of resistance mechanisms that they can use to evade the actions of carbapenems and other beta-lactams. The common form of resistance is either through lack of drug penetration (i.e., outer membrane protein (OMP) mutations and efflux pumps), hyperproduction of an AmpC-type beta-lactamase, and/or carbapenem-hydrolyzing beta-lactamases. Based on molecular studies, two types of carbapenem-hydrolyzing enzymes have been described: serine enzymes possessing a serine moiety at the active site, and metallo-β-lactamases (MBLs), requiring divalent cations, usually zinc, as metal cofactors for enzyme activity. MBLs, like all β-lactamases, can be divided into those that are normally chromosomally mediated and those that are encoded by transferable genes. The early studies on chromosomally mediated MBLs mainly centered around Bacillus cereus (BC II), and Stenotrophomonas maltophilia (L1). However, primarily due to genomic sequencing, increasingly more chromosomally mediated genes are being discovered but are often found across a range of bacterial genera.
KeywordsBacillus Cereus Reaction Tube Serratia Marcescens Stenotrophomonas Maltophilia Enterobacter Aerogenes
- 5.http://web.med.unsw.edu.au/cdstest/ Section 5.5.8 (accessed 10 November 2009)