亚胺培南耐药铜绿假单胞菌氨基糖苷类修饰酶基因型分布

The study of aminoglycoside-modifying enzymes gene in imipenem-resistant pseudomonas aeruginosa

目的调查成都地区亚胺培南耐药铜绿假单胞菌氨基糖苷类抗生素耐药特点及氨基糖苷类修饰酶基因型。方法琼脂稀释法测定庆大霉素、阿米卡星、妥布霉素、奈替米星、异帕米星、卡那霉素6种抗生素对23株耐亚胺培南铜绿假单胞菌的最低抑菌浓度。PCR法检测氨基糖苷类修饰酶编码基因。结果卡那霉素、庆大霉素对23株铜绿假单胞菌MIC50、MIC90均为256 mg/L,耐药率分别为100%和91.3%。阿米卡星、异帕米星、妥布霉素及奈替米星的耐药率分别为56.6%、65.2%、69.6%和78.3%。23株铜绿假单胞菌检出4种修饰酶基因,其中aac(3)-Ⅱ基因型12株,aac(6′)-Ⅰ基因型11株,ant(2″)-Ⅰ基因型6株,ant(3″)-Ⅰ基因型9株;12株菌株同时存在2种或2种以上基因型,1株菌株同时具有4种基因型。结论成都地区亚胺培南耐药铜绿假单胞菌对氨基糖苷类抗生素耐药率高,主要有aac(3)-Ⅱ、aac(6′)-Ⅰ、ant(2″)-Ⅰ和ant(3″)-Ⅰ四种氨基糖苷类修饰酶基因型。

Objective To study the antibiotic resistant characteristics and the genotypes of aminoglyco- side-modifying enzymes of pseudomonas aeruginosa resistant to imipenem. Methods The minimum inhibitory concentrations （MICs） of gentamicin, amikacin, tobramycin, netilmicin, isepamicin and kanamycin were detected in 23 strains of imipenem resistant pseudomonas aeruginosa by agar dilution method. The PCR was performed to determine the genotypes of aminoglycoside-modifying enzymes. Results MIC50 and MIC90 of kanamycin and gentamicin in 23 strains were 256 mg/L and resistant rates were 100% and 91.3%, respectively.The resistant rates to amikacin, isepamicin, tobramycin and netilmicin were 56.6 %, 65.2 %, 69.6 % and 78.3 %, respectively. Four genotypes of aminoglycoside-modifying enzymes were found in 23 strains as aac（3）- Ⅱ in 12 strains, aac（6＇ ）- Ⅰ in 11 strains,ant（2＂）- Ⅰ in 6 strains and ant（3＂）- Ⅰ in 9 strains. 12 strains harbored two or more genotypes simuhaneously. There was 1 strain harbored four genotypes, Conclusion Pseudomonas aeruginosa resistant to imipenem in Chengdu region are highly resistant to aminoglycasides and aac（3）-Ⅱ , aac （6＇）- Ⅰ , ant（2＂）- Ⅰ and ant（3＂）- Ⅰ are predominant resistant genotypes.