Yonsei Med J.  1998 Dec;39(6):520-525. 10.3349/ymj.1998.39.6.520.

Plasmid-encoded AmpC beta-lactamases: how far have we gone 10 years after the discovery?

• Bauernfeind A
• Chong Y
• Lee K

• KMID: 711593
• DOI: http://doi.org/10.3349/ymj.1998.39.6.520

Abstract

The dogma that ampC genes are located exclusively on the chromosome was dominant until about 10 years ago. Since 1989 over 15 different plasmid-encoded AmpC beta-lactamases have been reported from several countries. Most of these enzymes evolved in two clusters. The major cluster includes several enzymes with a high similarity to CMY-2, which is the closest related chromosomal AmpC enzyme of Citrobacter freundii. A second cluster centers around CMY-1. It is less homogeneous and not closely related chromosomal AmpC enzymes. Molecular diversification by amino acid substitutions does not usually translate into a change in the resistance phenotype. At this time, CMY-2 appears to be the most prevalent and widely distributed. Further global increase of prevalence and diversity of plasmidic AmpC beta-lactamases have to be anticipated in the next millenium.

Keyword

AmpC beta-lactamases; plasmid-encoded beta-lactamases; CMY-1; CMY-2; molecular evolution of beta-lactamases

MeSH Terms

Microbiology/trends
Plasmids/genetics*
Structure-Activity Relationship
Tissue Distribution
beta-Lactamases/metabolism
beta-Lactamases/genetics*