产质粒介导AmpC酶和ESBLs细菌的耐药性及β-内酰胺酶基因型研究  

Study on β-lactams resistance and genotype of β-lactamases in plasmid-mediated AmpC β-lactamases and ESBLs producing bacteria

作　　者：张永标[1] 张扣兴[1] 唐英春[1] 陆坚[1] 宋玮[1] 朱家馨[1] 谈淑卿[1] 

机构地区：[1]中山大学附属第三医院呼吸内科,广州510630

出　　处：《中华微生物学和免疫学杂志》2004年第7期577-582,共6页Chinese Journal of Microbiology and Immunology

摘　　要：目的　了解我院同时产质粒介导AmpC酶和超广谱 β 内酰胺酶 (ESBLs)肺炎克雷伯菌与大肠埃希菌的耐药性及其 β 内酰胺酶的基因型特征。方法　 110株临床分离无重复肺炎克雷伯菌与大肠埃希菌耐药株 ,采用酶提取物三维实验检测AmpC酶 ,美国临床实验室标准委员会 (NCCLS)表型筛选和确认实验检测ESBLs ;琼脂二倍稀释法测定抗生素对同时产AmpC酶和ESBLs菌株的最低抑菌浓度 (MICs) ;等电聚焦实验测定 β 内酰胺酶等电点 (pIs) ;质粒接合实验定位耐药基因 ;PCR通用引物扩增AmpC酶与ESBLs基因及其序列测定以确定其基因亚型。结果　同时产AmpC酶和ESBLs菌株在肺炎克雷伯菌与大肠埃希菌中的检出率分别为 7.7% (5 6 5 )、8.9% (4 4 5 )。该类产酶菌株产 2～ 3种pI5 .4～ 9.0 β 内酰胺酶 ,对第三代头孢菌素、氨曲南、头孢美唑和含酶抑制剂复合制剂的敏感性极低 ,但对亚胺培南均敏感。 9株质粒中均检出AmpC酶基因DHA 1亚型 ,其中 1株同时检出ACT 1亚型 ;ESBLs基因亚型分别为CTX M 14、CTX M 3、CTX M 9,各有 4、3、2株 ;有 3株还携带广谱酶TEM 1基因。结论　我院存在同时产质粒介导DHA 1、ACT 1型AmpC酶和CTX M型ESBLs肺炎克雷伯菌、大肠埃希菌流行株 ,药敏检测结果显示对大多数新型广谱 βObjective To investigate the β-lactams resistance and genotype characteristics of β-lactamases in plasmid-mediated AmpC β-lactamases and extended-spectrum β-lactamases (ESBLs) producing K.pneumoniae and E.coli . Methods A total of 110 clinical isolates of nonrepetitive drug-resistant K.pneumoniae and E.coli were detected by three-dimensional extract test for AmpC β-lactamases and phenotypic confirmatory test based on the National Committee for Clinical Laboratory Standard (NCCLS) criteria for ESBLs. The minimal inhibitory concentrations (MICs) on AmpC β-lactamases and ESBLs producing strains and the isoelectric points(pIs) of β-lactamases were determined by standard agar dilution and isoelectric focusing(IEF). Drug resistant gene were positioned by plasmids conjugation experiments. Universal primer PCR for AmpC and ESBLs gene amplification and DNA sequencing were carried out for genotype of β-lactamases. Results The incident rate of AmpC β-lactamases and ESBLs producing strains were 7.7%(5/65) in K.pneumoniae and 8.9%(4/45) in E.coli. The sensitivity to third-generation cephalosporins,aztreonam,cefmetazole and antibiotics combined with inhibitors for AmpC β-lactamases and ESBLs producing strains was very low,but all sensitive to imipenem. IEF demonstrated that 9 isolates displayed 2-3 bands of β-lactamases activity with pI 5.4-9.0. AmpC β-lactamases were DHA-1 type in 9 strains,ACT-1 was also identified in 1. ESBLs were CTX-M type with CTX-M-14,CTX-M-3 and CTX-M-9 in 4,3,2 strains respectively. Furthermore,3 of them were also found to carry broad-spectrum β- lactamases TEM-1 gene. Conclusion There are epidemic strains of K.pneumoniae and E.coli producing plasmid-mediated DHA-1,ACT-1 type AmpC β-lactamases and CTX-M type ESBLs in our hospital,sensitivity test shows that they are resistant to the most new broad-spectrum β-lactamas but sensitive to imipenem.

关 键 词：质粒 AMPC酶 ESBLs细菌 耐药性 Β-内酰胺酶 基因型 

分 类 号：R378[医药卫生—病原生物学]