Detection of Plasmid-Borne AmpC Beta Lactamase Enzyme Types in Cefoxitin Resistant or Intermediate Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis Isolates by using Multiplex PCR and Sequencing

Plasmid mediated AmpC beta lactamases are reported from Enterobacteriaceae with increasing frequency. Unfavorable clinical outcomes in patients infected with these organisms and treated with broad-spectrum cephalosporins have been reported. The aim of our study is to investigate plasmid mediated AmpC beta lactamases in E. coli and Klebsiella spp.. 41 strains of cefoxitin resistant or intermediate E. coli (27 isolates) and Klebsiella spp. (14 isolates) were collected from January 2005 to January 2006 at Akdeniz University Hospital Central Laboratory. Three-dimensional test was used as a phenotypic confirmatory test. Analytical isoelectric focusing electroforesis was used to measure the pI value of the beta lactamases. Plasmid mediated AmpC enzymes were amplified by using multiplex polymerase chain reaction and sequenced by Beckman Coulter CEQ 8000. AmpC beta lactamases were only detected in two isolates of E. coli. These isolates produced CMY-2 like enzymes and have either CTX-M and TEM type enzyme. Transferable AmpC beta lactamases are associated with multiple antibiotic resistance. Therefore detection of the enzymes in gram negative bacteria has a clinical importance, since it can often provide valuable information to clinicians loading to more effective and appropriate use of antimicrobials. Key words: Klebsiella spp., E. coli, plasmid-borne AmpC beta lactamases