儿童感染肺炎克雷伯菌质粒型AmpC酶基因分型及随机扩增DNA多态性分析

目的了解儿童感染肺炎克雷伯菌的耐药情况、产质粒介导的AmpC酶的基因型别及产酶株的分子流行病学特征。方法采用K—B纸片法检测广州市儿童医院患儿感染的肺炎克雷伯菌的耐药情况；头孢西丁三维试验检测AmpC酶；多重PCR技术检测ampC基因并经DNA测序确定其基因型别；RAPD技术对产酶株进行DNA多态性分析。结果在分离到的110株肺炎克雷伯菌中，产质粒型AmpC酶肺炎克雷伯菌的分离率达17．3％，产酶株对头孢菌素类、头霉素类及复方β-内酰胺类抗生素高度耐药，但对亚胺培南仍全部敏感。多重PCR及DNA测序显示AmpC酶的基因型均为DHA型。多态性分析结果显示19株产AmpC酶菌株可分为15个谱型，其中A型有3株菌，B型、C型各两株，另12株菌谱型各不相同；C型两株产酶株分布于同一病区，而A型、B型产酶株则分布于不同病区。结论本地区儿童感染的肺炎克雷伯菌多重耐药情况严重；质粒介导的AmpC酶的检出率较高，其基因型为DHA型；产酶株主要为散发感染。

Genotyping of plasmid-mediated AmpC and randomly amplified polymorphic DNA in Klebsiella pneumoniae in children

Objective To investigate the antimicrobial susceptibility,genotyping of plasmid-mediated AmpC beta-lactamases and and the molecular epidemiology characteristic of K.pneumoniae in children.Methods The antibiotics susceptibility of K.pneumoniae was tested by Kirby-Bauer methods.AmpC beta-lactamases was detected by three-dimensional extract test.Genotypes of AmpC betalactamases were determined by multiplex PCR and DNA sequencing.And the randomly amplified polymorphic DNA technique was used in epidemic analysis of AmpC producers.Results Among the 110 isolates collected,19 strains produced AmpC β-lactamases.The strains of AmpC beta-lactamases producers were highly resistant to the third-generation cephalosporins,cefoxitin and antibiotics combined with inhibitors,but all sensitive to imipenem.The genotypes of AmpC beta-lactamases were DHA type.Randomly amplified polymorphic DNA analysis indicated that 19 strains had 15 types,in which 3 strains were type A,2 strains were type B,2 strains were type C,and the other 12 strains were different typed.Two C typed AmpC beta-lactamases producing strains were distributed in the same ward,while A and B typed AmpC beta-lactamases producing strains were distributed in different wards.Conclusion The resistance of K.pneumoniae in children in our area is serious and the detection rate of AmpC beta-lactamases producing strains is higher.The genotype of AmpC beta-lactamases is DHA type.AmpC beta-lactamases producing K.pneumoniae is mostly characteristic of diverging infection.