大肠埃希菌ICU分离株发现aadA4/5、aph(3′)-Ⅰ型氨基糖苷类修饰酶基因

Drug-resistant Genes aadA4/5 and aph(3′)-Ⅰ Associated with Aminoglycosides Be Found Existing in Escherichia coli Isolated from ICU

目的了解分离于ICU的大肠埃希菌(ECO)氨基糖苷类药物各种耐药相关基因存在状况,探讨ECO多药耐药机制。方法收集2007年12月-2008年6月20株分离自医院ICU患者临床标本的ECO,采用纸片扩散法测定30种抗菌药物的敏感性;采用PCR法检测armA、rmtB、npmA、aac(3)-Ⅰ、aac(3)-Ⅱ、aac(6′)-Ⅰb、aac(6′)-Ⅱ、ant(3″)-Ⅰ、ant(2″)-Ⅰ、ant(4′)-Ⅰa/b、aadA4/5、aadA6/16、aph(3′)-Ⅰ、aph(3′)-Ⅱb、aph(3′)-Ⅵa、3种16S rRNA甲基化酶与12种氨基糖苷类修饰酶基因。结果20株ECO中检出aac(3)-Ⅱ8株(40%)、aac(6′)-Ⅰb 3株(15%)、ant(3″)-Ⅰ3株(15%)、aph(3′)-Ⅰ1株(10%)a、adA4/5 13株(65%)5种氨基糖苷类修饰酶基因,未检出16S rRNA甲基化酶基因;在ECO中发现aadA4/5和aph(3′)-Ⅰ型氨基糖苷类修饰酶基因均为国内首次。结论ECO对氨基糖苷类药物耐药情况严重、机制复杂,产氨基糖苷类修饰酶为主要原因之一。

OBJECTIVE To investigate the antibiotics resistance of Escherichia coli （ECO） and distrubtion of aminoglycoside-modifying enzymes and 16S RNA methylase genes in ICU. METHODS The samples of 20 ECO isolates were collected from Dec 2007 to Jun 2008 of patients in ICU. To determine the sensitivity to the 30 antibacterials K-B method was used and aminoglycoside-modifying enzymes and 16S RNA methylase genes were analyzed by polymerase chain reaction （PCR）. RESULTS In among the 20 ECO isolates, 8 strains carried aac（3）-Ⅱ（40%）, 3 carried aac（6＇）-Ⅰ b（15%） and ant（3＂）-Ⅰ （15%）, 1 be found aph（3＇）-Ⅰ （10%）and 13 be found aadA4/5 aminoglycoside-modifying enzymes genes, no strain carried 16S RNA methylase genes. CONCLUSIONS aac（3）-Ⅱ ,aac（6＇）- Ⅰ b, ant（3＂）- Ⅰ, aph（3r）-Ⅰ and aadA4/5 aminoglycoside-modifying enzymes genes exist in ECO widely, they should be the main cause inducing the high rate of drug-resistance to aminoglycosides.