氨基糖苷类高水平耐药肠球菌的耐药及分子机制的研究

目的分析氨基糖苷类高水平耐药（HighLevelAminoglyeosideResistant，HLAR）肠球菌的耐药性与耐药基因，并研究其耐药分子机制。方法采用VITEK-2全自动鉴定仪法测定53株氨基糖苷类高水平耐药肠球菌对11种抗菌药物的最小抑菌浓度，用聚合酶链反应（PCR）检测肠球菌转座子Tn917和Tnl546／Tn916、红霉素耐药基因er—mB、毒力岛基因mefA、I类整合酶Intll、氯霉素耐药基cat、表面蛋白基因esp，并对万古霉素耐药肠球菌（Vancomy—cin—resistantEnterococc，VRE）进行基因分型（vanA、vanB、vanC）。结果53株肠球菌检出含ermB26株，占49．0％；含mefA9株，占17．0％；含Tnl546／Tn91619株，占35．8％；含Tn91711株，占20．8％；含Intll26株，占49．1％；含esp15株，占28．3％；未检出cat。53株肠球菌对复方新诺明全部耐药，对红霉素耐药高达94．3％，对高水平庆大霉素、高水平链霉素、环丙沙星、四环素和氨苄西林的耐药率分别为75．5％、73．6％、75．5％、66．0％、62．3％；对利奈唑胺和替考拉宁的敏感率高达98．1％；1株耐万古霉素，其基因和表型均为VanA。结论HLAR肠球菌可携带多种耐药基因，耐药基因与肠球菌耐药性密切相关，可能在多重耐药机制中起重要作用。

Study on Resistance and Molecular Mechanismin of High-level Aminoglycoside Resistance Enterococcus

Objective To investigate resistance and resistance genes from 53 clinical isolates of High Level Amin- oglyeoside Resistant（HLAR） Enterococcus. Methods MICs to 11 kinds of antibiotics were analyzed by VITEK-2. DNA was extracted from 53 strains of Enterococcus for analysis of drug resistant genes（ermB gene containing Erythromycin resistance, Virulence factor mefA gene,Transposition Tn1546/Tn916 and Tn917,Class I integrase gene IntI1, esp gene, cat gene）by PCR. The data were combined with drug sensitivity test to evaluate antimicrobial resistance characteristics. Results The results showed that positive rate of ermB gene was 49.0% （26/53）and mefA gene was 17.0 % （9/53）, Tn1546/Tn916 was 35.8%（19/53） and Tn917 was 20.8%（11/53）,IntI1 was 49. t%（26/53）,esp gene was 28. 3% （15/53）, cat gene was 0. Solated Enterococcus resistant to Trimethoprim/Sutfa was100 %, and to Erythromycin was 94. 3%. The resistance rates for High-level gentamicin and High-level streptomycin,Ciprofloxacin,Tetracycline and Ampi- cillin were 75.5 %. 73.6 %. 75.5 %. 66.0 % .62.3 % respectively. The strains of Enterococcus had a high sensitivity rate for Teicoplanin and Linezolid with 98.1%. There was one strain resistant to Vancomycin, its genotype and phenotype were all VanA. Conclusion HLAR Enterococcus carried several kinds of drug resistant genes. Mutual relationship be- tween drug resistant genes and resistance of Enterococcus was obvious,so drug resistant genes may play an important role in multiple drug resistance.