eptA过表达介导的临床分离的鲍曼不动杆菌多黏菌素耐药研究  

Study on polymyxin resistance mediated by eptA overexpression in Acinetobacter baumannii clinical isolates

作　　者：叶秀芬 俞容 周益琴[1] Ye Xiu-fen;Yu Rong;Zhou Yi-qin(Department of Clinical Laboratory,Jinhua People’s Hospital,Jinhua 321000)

机构地区：[1]金华市人民医院检验科,金华321000

出　　处：《中国抗生素杂志》2023年第4期433-437,共5页Chinese Journal of Antibiotics

基　　金：金华市科技局创新基金(No.2019-4-054)。

摘　　要：目的为了确定鲍曼不动杆菌除PmrCAB以外的多黏菌素耐药机制。方法收集2020年金华市人民医院住院患者痰液标本分离的3株鲍曼不动杆菌(AB1、AB2和AB3)。微量肉汤稀释法测定3株鲍曼不动杆菌对亚胺培南、美罗培南和多黏菌素的最低抑菌浓度。通过PCR明确菌株是否携带eptA并进一步对操纵子pmrCAB进行分析,明确是否存在氨基酸突变。全基因组测序分析菌株的ST型、耐药基因以及eptA的上游结构。使用荧光定量PCR技术检测多黏菌素耐药相关基因pmrB以及eptA基因的表达量。GraphPad Prism 8.0用于数据分析。结果3株鲍曼不动杆菌对多黏菌素耐药,MIC=16μg/mL。根据Pasteur分型,它们都属于ST2;根据Oxford分析,AB1和AB3属于ST208,AB2属于ST1806。3株鲍曼不动杆菌都携带bla_(OXA-23)碳青霉烯酶耐药基因,但都不存在PmrCAB氨基酸突变。表达量分析显示3株菌存在eptA过表达(P<0.01)。ISAba1的插入位点分别在eptA起始密码子之前第13和18个碱基处。然而,pmrCAB表达量改变差异无统计学意义(P>0.05)。结论ISAba1插入介导的eptA的过表达可能是新的鲍曼不动杆菌多黏菌素耐药机制之一。Objective To determine the polymyxin resistance mechanism in Acinetobacter baumannii(A.baumannii)other than PmrCAB.Methods Three A.baumannii clinical strains collected from sputum were selected in 2020.Minimal inhibitory concentrations(MICs)of imipenem,meropenem and colistin were tested by the broth micro-dilution method.PCR was conducted to test whether the strains carried eptA and further analyzed the pmrCAB mutation.The ST type,drug resistance gene,and the upstream structure of eptA of the strain were analyzed using whole-genome sequencing.Real-time quantitative PCR(qRT-PCR)was used to detect the expression of polymyxin resistance-related genes pmrB and eptA.Experimental data were analyzed using GraphPad Prism 8.0.Results Three A.baumannii strains were resistant to polymyxin,and MICs were all 16μg/mL.According to the Pasteur type,they all belonged to ST2;according to Oxford type,AB1 and AB3 belonged to ST208,and AB2 belonged to ST1806.Three strains all carried the bla_(OXA-23)carbapenemase resistance gene,but none of them had PmrCAB amino acid mutations.Expression analysis showed that the three strains had overexpression of eptA(P<0.01).The insertion sites of ISAba1 were 13 and 18 bases before the eptA start codon,respectively.However,there was no statistically significant difference in the expression of pmrCAB(P>0.05).Conclusion The overexpression of eptA mediated by the insertion of ISAba1 may be one of the new polymyxin resistance mechanisms in A.baumannii.

关 键 词：鲍曼不动杆菌 耐药 多黏菌素 EPTA 

分 类 号：R978.1[医药卫生—药品]