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 year 2004 to 2006,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 years 2004 and 2005,As for 2006,ACT-1 genotype has appeared in three strains. Conclusions Though plasmid mediated AmpC genes in Ningbo area is not quite prevalent in Escherichia coli and Klebsiella pneumoniae,there is an increasing tendency in recent years.