产新型β-内酰胺酶阴沟肠杆菌的耐药性及RAPD分型分析

Analysis of drug resistance and RAPD genotyping of Enterobacter cloacae producing new β-lactamases

目的了解医院感染阴沟肠杆菌的现状、耐药与流行状况。探讨产新型β-内酰胺酶阴沟肠杆菌的耐药机制与基因分型。方法细菌的药敏试验采用K-B法;产超广谱β-内酰胺酶、AmpC酶检测分别采用双纸片确证试验和三维试验;基因分型采用随机扩增多态性DNA(RAPD)法。结果60株阴沟肠杆菌中产超广谱β-内酰胺酶、AmpC酶分别为23株和32株,产新型β-内酰胺酶株14株。RAPD将60株阴沟肠杆菌分为7种株型。其中Ⅰ、Ⅱ型、Ⅲ型占68.3%,是主要的流行株。产新型β-内酰胺酶阴沟肠杆菌对11种常用抗生素的耐药率为21.3%～100%。结论医院感染阴沟肠杆菌对不同抗生素具有较高的耐药性,不同产酶类型对抗生素的耐药性不同。产新型β-内酰胺酶阴沟肠杆菌的出现与流行是阴沟肠杆菌多重耐药与高耐药的重要原因。

Objective To ascertain the status,drug resistance,and prevalence of Enterobacter cloacae infection in a hospital and to investigate the mechanisms of resistance and genotyping to produce new lactamases in E.cloacae.Methods The K-B method was used for antimicrobial susceptibility testing.Extended-spectrum β-lactamases（ESBLs） and AmpC β-lactamases were detected by a double disk test and three-dimensional extraction test.Genotyping was done using random amplified polymorphic DNA（RAPD）.Results Of 60 strains of E. cloacae identified, 23 produced ESBLs, 32 produced AmpC β-1actamase, and 14 produced new β-1actamases. According to RAPD analysis, the collection of 60 E. cloacae strains was divided into 7 genotypes, of which 68.3% were types Ⅰ,Ⅱ,and Ⅲ ,and these types were the maior epidemic strains. The strains of new ESBLs-producing were resistant to 11 common antibiotics at a rate of 21. 3% -- 100%. Conclusion E. cloacae nosocomial infection showed a high level of drug resistance, and the drug resistance of different types of β-lactamase produced by E. cloacae to different antibiotics differed. The appearance and prevalence of E. cloacae producing new β-lactamases are important factors for why E. cloacae becomes multidrug-resistant and highly resistant.