多重耐药鲍曼不动杆菌对氨基糖苷类药物耐药性及其耐药基因(ant)的研究

Study on aminoglycosides resistance and its resistance genes in multidrug resistant Acinetobacter baumannii

目的了解多重耐药鲍曼不动杆菌对氨基糖苷类药物修饰酶的耐药性及其耐药基因。方法用琼脂稀释法检测庆大霉素、阿米卡星、链霉素、卡那霉素、妥布霉素、奈替米星、新霉素7种药物对20株多重耐药性鲍曼不动杆菌的最低抑菌浓度(MIC);用PCR法检测两种氨基糖苷类药物核苷转移酶基因,并使用DNA测序加以证实。结果庆大霉素、阿米卡星、链霉素、卡那霉素对20株鲍曼不动杆菌的MIC50和MIC90均大于1024mg/L,耐药率分别为95%、95%、100%和90%;而妥布霉素、奈替米星和新霉素的耐药率分别为85%、90%、40%。从20株菌中检出ant(2″)-Ⅰ、ant(3″)-Ⅰ两种修饰酶基因,阳性率分别为55%、80%,10株细菌两种基因同时阳性,占50%。结论鲍曼不动杆菌对氨基糖苷类药物耐药与ant(2″)-Ⅰ、ant(3″)-Ⅰ基因有非常密切的关系。

Objective To investigate the resistance of multi-drug resistant Acinetobacter baumannii against aminoglycosides and its resistance genes. Methods The minimal inhibitory concentrations （MICs） of seven antimicrobials （gentamicin, amikacin, tobramycine, netilmicin, neomycin, streptomycin and kanamycin） against 20 strains of multi-drug resistant Acinetobacter baumannii were detected by agar dilution method. Meanwhile, two resistance genes of aminoglycoside nucleotidyltransferase were amplified by PCR and vertified by DNA sequencer. Results It was found that MIC50 and MIC90 of gentamicin, amikacin, streptomycin and kanamycin in 20 strains of Acinetobacter baumannii were all above 1 024 mg/L, and their resistant rates were 95%, 95%, 100% and 90% respectively, while the resistant rates of tobramycin, netilmicin and neomycin were 85 %, 90 % and 40 % respectively. Two aminoglycoside-modification genes ant （2＂）-I and ant （3＂）-I were detected in 20 strains, with 55% and 80% of positive rate respectively. The double positive rate of two resistance genes was 50%. Conclusion The resistance of multi-drug resistant Acinetobacter baumannii against aminoglycosides was closely associated with ant（2＂）- I and ant（3＂）- I genes.