Detection of plasmid-mediated AmpC β-lactamases genes in Escherichia coli and Klebsiella pneumoniae in Ningbo area

Objective To investigate the prevalence and genotype of plasmid-mediated AmpC β-lactamases genes in Escherichia coli and Klebsiella pneumoniae strains isolated from Ningbo area.Methods After the detection for drug resistant phenotypes by K-B method,positive strains were subjected by polymerase chain reaction(PCR),then qualified through three-dimension test.Results From 2009 to 2011,the positive rates of plasmid-mediated AmpC genes were 4.4%(2/45),8.6%(3/35),13.3%(8/60),respectively.Meanwhile,the unique genotype was DHA for all positive strains in 2009 and 2010.In 2011,ACT-1 genotype was detected in 2 strains of Escherichia coli and 1 strain of Klebsiella pneumoniae.Conclusion The plasmid mediated AmpC genes in strains of Escherichia coli and Klebsiella pneumoniae clinically isolated in Ningbo area Escherichia coli and Klebsiella pneumoniae show an increasing tendency in recent years.