儿科临床分离肠球菌的耐药性监测及大环内酯类耐药机制研究  

Bacteria resistance surveillance on Enterococci isolated from pediatric hospitals and distribution of resistance genes ermB, mefA, tetM and the integrase gene intTn of Tnl545 in Enterococci

作　　者：汪玲[1] 杨永弘[1] 陆权[2] 王艺[3] 陈沅[4] 邓力[5] 邓秋莲[5] 张泓[2] 王传清[3] 刘岚[4] 徐樨巍[1] 马耀玲[1] 沈叙庄[1] 

机构地区：[1]首都医科大学附属北京儿童医院检验科,100045 [2]上海交通大学附属上海市儿童医院检验科 [3]复旦大学附属儿科医院检验科 [4]重庆医科大学附属重庆儿童医院检验科 [5]广州市儿童医院检验科

出　　处：《中华检验医学杂志》2008年第9期984-988,共5页Chinese Journal of Laboratory Medicine

摘　　要：目的研究儿科临床分离肠球菌的流行情况及红霉素耐药株基因ermB、mefA、tetM与转座子整合酶基因int-Tn分布特点。方法采用KB纸片法对北京、上海、广州和重庆5家儿科专科医院2000-2006年临床分离粪、屎肠球菌进行8种抗菌药敏感性试验，并用琼脂稀释法测定225株红霉素耐药粪、屎肠球菌对大环内酯类及四环素最小抑菌浓度。PCR检测红霉素耐药基因ermB和mefA，四环素耐药基因tetM，以及转座子Tn1545的整合酶基因int-Tn。结果4地5家儿童医院分离所得肠球菌对红霉素耐药率最高，平均耐药率86．5％；对氨苄西林、高浓度链霉素、高浓度庆大霉素、环丙沙星及利福平的耐药率分别为48．0％、47．6％、60．5％、45．4％、63．6％；未发现对万古霉素耐药的肠球菌。225株红霉素耐药粪、屎肠球菌ermB基因阳性率为70．7％，仅发现1株对mefA阳性的菌株。tetM基因阳性率为75．1％。Tnl545基因阳性株组ermB和tetM的携带率分别为84．8％和83．7％，高于阴性组60，9％和70．0％，且差异均有统计学意义（P均〈0．05）。结论我国儿科临床分离粪、屎肠球菌对多种抗菌药均有较高耐药率，对糖肽类抗菌药均保持较好敏感性，分离株对红霉素和四环素耐药主要机制分别是ermB编码的靶位改变和tetM编码的核糖体保护作用；接合性转座子Tnl545与tetM和ermB存在关系密切，可能是肠球菌多重耐药的重要机制之一。Objective To determine the drug-resistance rate of Enterococci isolated from patients of 5 padiatric hospitals located at different areas in China, and to investigate the distribution of resistance genes ermB,mefA, term and the integrase gene intTn of Tnl545 in Enterococci. Methods The antimicrobial susceptibility to 8 antibiotics of 2 216 Enterococci isolates was determined. PCR was used to detect the macrolide resistance genes ermB and mefA, tetracycline resistance genes tetM, and the integrase gene int-Tn of Tnl545. Results The resistance rates to erythromycin, ampicillin, gentamicin and teicoplanin were 86. 5% ,48.0% , 60. 5% and 0.7% , respectively. All isolated Enterococci strains were found sensitive to vancomycin. Of the detected 225 strains, 70. 7% of the 225 detected strains carried ermB gene while 75.1% of them carried tetracycline resistance gene tetM ; only one strain had mefA. The presence of ermB gene in erythromycin MIC 〉 256 mg/L strains group（95.7% ） strains was higher than those in erythromycin MIC 〈 256 mg/L group （ 2. 5% ）. The int-Tn gene was detected in 40. 9% （ 92/225 ） of the 225 test strains. The presence of ermB gene in int-Tn positive group strains was higher（ 84. 8% ） than those in int-Tn negative strains group（60.9% ）. So did the tetM in int-Tn positive group （83.7%） compared with those in int-Tn negative group （70.0%）. Conclusions Enterococci showed a high resistance rate to the antibiotics we monitored, especially to erythromycin;but still very senstive to glycopeptide antibiotics. Resistance to macrolide in Enterococci collected from clinical in five Children＇s Hospital was generally mediated by methylation of 23S rRNA via ermB methylase. Enterococci resistance to tetracycline was predominantly due to ribosomal protection encoded by tetM. There was a strong relationship of the ermB and tetM genes with Tnl545-related elements.

关 键 词：肠球菌属 抗药性 多种 细菌 大环内酯类 药物监测 DNA可移植因子 

分 类 号：R686[医药卫生—骨科学]