A study on resistance and genotypes of AmpC beta-lactamase producing Klebsiella pneumoniae in Anhui province

Objective To identify the plasmid-mediated AmpC gene and to investigate its prevalence in Klebsiella pneumoniae strains isolated in Anhui Province.Methods The AmpC-producing isolates were chosen by cefoxitin and identified by the three-dimensional test.The plasmid-mediated AmpCβ-lactamases were detected by multiplex PCR.The PCR products were directly sequenced and analyzed. M-H agar dilution method was used to determine MIC of 17 antimicrobial agents against the AmpC positive isolates.Results Of the 180 strains,21(11.67%) proved to be plasmid-mediated highly productive AmpC by DNA sequence test.Blast results indicated that the positive AmpC group was composed of 17 strains which carried DHA type and 4 strains which carried EBC type.DNA sequence analysis revealed three novel AmpC genotypes(GenBank accession:FJ237366,FJ237367,and FJ237368).All AmpC positive isolates exhibited high resistance to the third or fourth generation cephalosporins,aminoglycosides,and quinolones.But all of them were susceptible to imipenem and meropenem.Conclusions The plasmid-mediated AmpCβ-lactamases were found in Klebsiella pneumoniae strains isolated in Anhui Province and DHA type was dominant.Moreover,three novel AmpC genotypes were identified.The carbapenems are recommended to treat the AmpC-producing isolates.