尿路感染产KPC-2酶肺炎克雷伯菌对磷霉素耐药机制研究

Antibiotic resistance mechanism of KPC-2-producing Klebsiella pneumoniae by urinary tract infection to fosfomycin

目的探讨尿路感染产KPC-2酶肺炎克雷伯菌对磷霉素的耐药情况及机制。方法收集2017年1月-12月浙江省人民医院分离的产KPC-2酶肺炎克雷伯菌16株,采用琼脂稀释法测定磷霉素敏感性;对磷霉素耐药基因fosA、fosB、fosC、fosX进行PCR扩增及测序分析;对磷霉素耐药肺炎克雷伯菌株进行多克隆位点序列测定及质粒接合试验。结果收集的16株尿路感染产KPC-2酶肺炎克雷伯菌对磷霉素的耐药率为43.8%(7/16),7株磷霉素耐药株均携带fosA3耐药基因,未检到fosB、fosC、fosX耐药基因;携带fosA3基因的产KPC-2酶肺炎克雷伯菌均为ST11型别,并通过接合实验将fosA3转移至受体菌E.coli J53中。结论基因fosA3是介导本院尿路感染产KPC-2酶肺炎克雷伯菌磷霉素耐药的主要机制。此外,以ST11克隆型别为主的产KPC-2酶肺炎克雷伯菌对磷霉素耐药具有较高水平,临床应谨慎选择磷霉素作为治疗尿路感染产KPC酶肺炎克雷伯菌感染的辅助药物。

Objective To explore the resistance mechanism of KPC-2-producing K. pneumoniae to fosfomycin. Methods Sixteen strains of KPC-2-producing K. pneumoniae isolated from Zhejiang Provincial Hospital from January 2017 to December 2017 were collected for study. The minimum inhibitory concentration of fosfomycin was determined by agar dilution method. The fosfomycin resistance gene fosA, fosB, fosC and fosX were conducted for PCR amplification and sequencing analysis. The fosfomycin-resistant Klebsiella pneumoniae strains were conducted for polyclonal site sequence determination and plasmid ligation assay. Results The resistance rate to fosfomycin of KPC-2-producing K. pneumoniae strains was 43.8%(7/16). The fosA3 resistance gene was found in 7 strains and no fosB, fosC and fosX resistance genes were detected. Fosfomycin resistance KPC-2-producing K. pneumoniae strains were all ST11 type. The fosA3 gene of 7 KPC-2-producing K. pneumoniae strains was able to transfer to the recipient E.coli J53 by conjugation experiment. Conclusion The resistance mechanism of KPC-2-producing K. pneumoniae strains caused by urinary tract infection to fosfomycin was fosfomycin resistant gene(fosA3). In addition, KPC-2-producing K. pneumoniae strains of ST11 type has a high resistance level to fosfomycin. Fosfomycin should be selected carefully as adjuvant drugs in clinical treatment of urinary tract infection caused by KPC-2-producing K. pneumoniae.