产AmpC酶肺炎克雷伯菌的耐药性及基因型研究

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

目的了解安徽地区产AmpC酶肺炎克雷伯菌的基因型特征及耐药性。方法对180株肺炎克雷伯菌进行头孢西丁纸片法初筛,三维实验筛选高产AmpC酶菌,PCR扩增、测序和BLAST比对分析以确定AmpC基因型,琼脂稀释法检测耐药性。结果产AmpC酶菌株有21株(11.67%),其中DHA型17株,EBC型4株。3株EBC型为新基因(gene bank登录号为FJ237366,FJ237367,FJ237368);药敏显示产酶株除对亚胺培南与美罗培南敏感外,对其他抗菌药物均有不同程度的耐药。结论安徽地区产AmpC酶的肺炎克雷伯菌以DHA型为主,同时存在EBC型突变株。高产AmpC酶菌的感染推荐使用碳青霉烯类抗生素治疗。

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.