产超广谱β-内酰胺酶大肠埃希菌对氨基糖甙类药物耐药性及耐药基因研究

目的研究产超广谱β-内酰胺酶（ESBLs）大肠埃希菌对氨基糖甙类药物的耐药特性及耐药基因表达。方法用琼脂稀释法检测庆大霉素、阿米卡星、卡那霉素、妥布霉素、奈替米星和新霉素6种药物对37株产ESBLs大肠埃希菌的最低抑菌浓度。用PCR法检测5种氨基糖甙类药物修饰酶基因,并使用DNA测序加以证实。结果庆大霉素、阿米卡星、卡那霉素、妥布霉素和奈替米星对37株大肠埃希菌MIC50、MIC90均大于256mg／L,其耐药率分别为78．4％、45．9％、72．9％、83．8％和64．9％,而新霉素仍具有较高的抗菌活性。从37株菌中检出5种修饰酶基因,aac（3）-Ⅱ、aac（6′）-Ⅰb、aac（6′）-Ⅱ、ant（2″）-Ⅰ、ant（3″）-Ⅰ阳性率分别为56．8％、27．0％、2．7％、5．4％和13．5％,未发现aac（3）-Ⅰ基因。结论产ESBLs的大肠埃希菌对氨基糖甙类药物的耐药与修饰酶基因的表达有关。

Study on aminoglycoside resistance and drug resistance gene of ESBLs-producing Escherichia coil

Objective To investigate the characteristics of aminoglycoside resistance of extend-ed-spectrum β-lactamases(ESBLs)-producing Escherichia coli(E, cold and expression of aminoglyco-side-modifying enzyme genes. Methods The minimal inhibitory concentrations(MICs) of gentamicin,amikacin, kanamycin, tobramycin, netilmicin and neomycin for 37 strains of ESBLs-producing E. Coli were detected by agar dilution. In addition, six aminoglycoside-modifying enzyme genes were amplified by polymersae chain reaction(PCR) and verified by DNA sequencing. Results MIC and MIC90 of gentamicin, amikacin, kanamycin, tobramycin and netilmicin for 37 strains of ESBLs-producing E. Co-Il all excelled 256 μg/mL, the resistance rates of the above antibiotics were 78.4%, 45.9%, 72.9%,83.8%and 64.90%, respectively. However, neomycin still had powerful antibacterial activity. In ad-dition, five modifying enzyme genes, including aac(3)-Ⅱ , aac(6′)-Ⅰ b, aac(6′)-Ⅱ , ant(2″)-Ⅰ and ant(3″)- Ⅰ genes, were found in 37 isoaltes except aac(3)- Ⅰ , and their positive rates were 56.8%,27.0 %, 2.7 %, 5.4 % and 13. 5 %, respectively. Conclusion The aminoglycoside resistance of ES-BLs-producing E. Coil may be associated with the expression of aminoglycoside-modifying enzyme genes.