儿童呼吸道感染肺炎克雷伯菌质粒介导产AmpC酶的耐药性及基因型研究

Detection of drug resistance due to the plasmid-mediated AmpC β-lactamase and genotype analysis in Klebsiella pneumoniae resulting in respiratory infectious in children

目的 探讨小儿呼吸道感染肺炎克雷伯菌AmpC酶的产生、AmpC酶的耐药基因型及对常用抗菌药物的耐药特征,为临床治疗提供选药参考.方法 采用VITEK-60型全自动细菌鉴定仪鉴定细菌,按CLSI推荐的确证试验检测ESBLs和K-B纸片法测定药敏结果；采用头孢西丁纸片扩散法筛选疑产AmpC酶阳性菌株,并通过酶粗提物头孢西丁三维试验、接合试验、PCR测序等实验分析该菌株的基因型.结果 135株肺炎克雷伯菌ESBLs和AmpC酶总检出率分别为30.37％和15.56％,其中,单产AmpC酶、同产AmpC酶＋ESBLs、单产ESBLs检出率分别为8.15％、7.41％和22.96％；AmpC酶阳性菌株的耐药基因型：19株为DHA-1型,2株为ACT-1型.产酶株的耐药性明显高于非产酶株,耐药现象在同产AmpC酶和ESBLs菌株中更为严重,产与非产AmpC酶（和）ESBLs菌株对亚胺培南的敏感率几乎达100％.结论 台州地区小儿呼吸道感染肺炎克雷伯菌产AmpC酶和ESBLs菌株检出率较高,AmpC酶以DHA-1基因型为主.产AmpC酶和ESBLs的菌株呈高度耐药,限制β内酰胺类抗菌药物的应用是减少产酶株流行的重要措施.

Objective To investigate the production and AmpC β-lactamase in Klebsiella （K.）pneumoniae resulting in respiratory infections in children,AmpC β-Lactamase genotypic resistance and typical resistance to common antibiotics so as to provide some references for selecting drugs in clinical treatment.Method Microbiological identification was performed with the VITEK 60 System,extended spectrum β lactamases （ESBLs） were detected in accordance with the confirmatory test recommended by Clinical and Laboratory Standards Institute （CLSI） and drug sensitivity was determined with Kirby-Bauer method.Suspected positive strains of AmpC β-lactamase were screened with cefoxitin disk diffusion.The genotypes were analyzed by cefoxitin three-dimensional test,conjugation test and PCR sequencing.Result Of the 135 isolates,30.37% were ESBLs positive,15.56% were AmpC β-lactamase positive.The positive rates for only AmpC β-Lactamase,both AmpC β-Lactamase and ESBLs,and only ESBLs were 8.15%,7.41% and 22.96% respectively.The resistant genotypes for AmpC β-Lactamase-positive strains was that 19 strains were of DHA-1 type and 2 were of ACT-1 type.The resistance to drugs in β-lactamase-producing strains was obviously higher than that in non-β-lactamase-producing strains and more serious in those strains producing both AmpC β-Lactamase and ESBLs.Sensitivity of β-lactamase,non-β-lactamase and ESBLs producing strains to imipenem was as high as 100 percent.Conclusion ESBLs- and AmpC-β-lactamase-producing strains of K.pneumoniae resulting in respiratory infections in children in Taizhou city,have a higher detection rate in Taizhou and AmpC-β-lactamase is mainly of DHA-1 genotype.AmpC-β-lactamase-and ESBLs-producing strains are highly resistant,so to restrict the use of β-lactam antibiotics is an important step to reduce the epidemic of β-lactamase-producing strains infection.