湖北地区产CTX-M型超广谱β内酰胺酶肺炎克雷白菌基因型与耐药特征研究

Genotype and Drug Resistance of Klebsiella Pneumoniae from Hubei Expressing CTX-M Extended Spectrum Beta-lactamase

目的了解湖北地区产CTX-M型超广谱β内酰胺酶(ESBLs)肺炎克雷白菌的流行基因型和耐药特征,为医师合理使用抗生素提供理论依据。方法临床分离的无重复产ESBLs肺炎克雷白菌70株,采用NCCLS表型筛选和确证实验检测ESBLs,PCR-RFLP检测blaCTX-M及分型,KB纸片法检测产CTX-M酶株对9种抗菌药的体外抗菌活性,质粒接合实验,随机扩增多态性DNA分型法(RAPD)进行克隆株的DNA同源性分析。结果CTX-M型ESBLs有26株(46%),均为CTX-M-1亚型,其中CTX-M-3型最常见;产CTX-M菌株对多种抗生素耐药,但对亚胺培南的敏感性为100%;CTX-M型ESBLs介导的耐药可水平转移,DNA同源性分析显示其为不同的克隆株。结论亚胺培南可作为治疗产CTX-M型ESBLs的首选药物,产CTX-M型ESBLs菌株的传播机制以质粒介导的为主,应加强湖北地区产CTX-M型ESBLs菌株的分子流行病学检测。

Objective To explore the transmission mechanisms of Klebsiella pneumoniae from Hubei expressing CTX-M β-1actamases, providing bases for rational use of antibiotics in clinic. Methods A total of nonrepetitive 70 K. pneunoniae producing ESBLs were detected by phenotypic confirmatory, test based on NCCLS criteria. PCR-RFLP and DNA sequencing were carried out for blaCTX-M typing; Susceptibility of the CTX-M producing strains to 9 antibiotics was performed through a disk diffusion test; DNA homology of clonal strains was analyzed by plasmid transfer experiments and RAPD. Results Tbe incidence of CTX-M expression was 46% in ESBLs-producing isolates, all of which was CTX-M-1 subtype, and CTX-M-3 was the most common type. The strains with CTX-M were resistant to a lot of antibiotics, but 100% sensitive to imipenem. The resistance mediated with ESBLs in CTX-M strains was horizonly transferred. The strains were from different clones by DNA homological analysis. Conclusion Imipenem could be the drug of first choice for treating K. pneumoniae with CTX-M β- lactamases-producing strains. The transmission of CTX-M producing strains is mainly mediated by plasmids, whicb forees us to intensify the detection of ESBLs strains with CTX-M type in Hubei province.