Characterization of blaCMY-10 a novel, plasmid-encoded AmpC-type beta-lactamase gene in a clinical isolate of Enterobacter aerogenes.
OBJECTIVE
We report the description of a novel plasmid-encoded AmpC beta-lactamase gene (blaCMY-10) from Enterobacter aerogenes K9911729 that was isolated from a patient suffering from pneumonia in South Korea.


RESULTS
Using antibiotic susceptibility testing, plasmid analysis, transconjugation and Southern blot analysis, the cefoxitin resistance phenotype reflects the presence of a large plasmid [pYMG-1 (130 kb)] in Ent. aerogenes K9911729. One beta-lactamase with the pI of 8.0 from transconjugant of Ent. aerogenes K9911729 was identified by isoelectric focusing on a gel. A 1475 bp DNA fragment containing the blaCMY-10 gene, identified on pYMG-1 of Ent. aerogenes K9911729, was sequenced and an open reading frame coding for 382 amino acid, CMY-10, was found. The 37 class C beta-lactamases were subclassified into 1a to 1j and CMY-10 into 1a by phylogenetic analysis. A sequence identical to the common regions in In6, In7 and a novel integron from pSAL-1 was found upstream from blaCMY-10 gene at nucleotide 1-71.


CONCLUSIONS
These results clearly show that blaCMY-10 gene belongs to the group of ampC-related bla genes. Homology analysis among AmpC enzymes or ampC genes implied that integration of the chromosomal ampC gene into a large resident plasmid, followed by transconjugation, was involved in the evolution of blaCMY-10 gene.


CONCLUSIONS
The first identification of the blaCMY-10 gene is of concern as chromosomal beta-lactamases may cause serious therapeutic problems if their genes are translocated onto plasmids.
Lee
S H
SH
Department of Biological Science, Myongji University, San 38-2 Namdong, Yongin, Kyunggido, South Korea. sanghee@mju.ac.kr
Jeong
S H
SH
Park
Y-M
YM
D001483:Base Sequence; D015139:Blotting, Southern / Q000379:methods; D002440:Cefoxitin; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial; D021902:Enterobacter aerogenes / Q000145:classification / Q000235:genetics*; D006801:Humans; D007525:Isoelectric Focusing / Q000379:methods; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics; D011014:Pneumonia / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods; D001618:beta-Lactamases / Q000235:genetics*
D002440:Cefoxitin; D001618:beta-Lactamases