CAJ | 학술논문

目的：研究鲍氏不动杆菌（ ABA）临床分离株对喹诺酮类抗生素耐药机制。方法收集来自6家医院的114株耐环丙沙星ABA临床分离菌株，PCR扩增喹诺酮类抗生素结合靶基因（ gyrA、gyrB、parC和parE），并进行序列测定，与参考菌株ATCC17978基因组进行比对，确定其喹诺酮耐药决定区是否存在耐药相关突变；PCR扩增9个质粒介导的喹诺酮类耐药基因[qnrA、qnrB、qnrC、qnrD、qnrS、qepA、aac（6′）-Ⅰb-cr、oqxA和oqxB]，并对阳性扩增产物进行测序以确定基因亚型。结果绝大部分菌株（113/114，99．1％）的gyrA基因发生了Ser83 Leu突变，其中67株菌（67/114，58．8％）同时发生了parC基因的Ser80Leu突变，以上两种突变是常见的喹诺酮耐药相关突变。与标准菌株进行比对，受试菌株gyrB基因Arg393Ser、Arg393Cys、Thr401Ala、Pro406Ser、Val430Phe、Cys440Ser和Gly480Arg突变率分别为95．6％、0．9％、96．5％、96．5％、100％、96．5％和96．5％；parE基因在7个位点发生了同义突变，突变率＞96％。83．3％（95/114）的菌株中检出aac（6′）-Ⅰb基因，但不存在“cr”突变，其余质粒介导的喹诺酮类耐药基因扩增均为阴性。结论该研究耐环丙沙星ABA中未发现质粒介导的喹诺酮耐药基因，在gyrB和parE基因中发现的突变可能与环丙沙星耐药性无关，实验菌株的环丙沙星耐药性主要与染色体上的喹诺酮耐药决定区GyrA-Ser83Leu和ParC-Ser80Leu两种突变相关。
목적：연구포씨불동간균（ ABA）림상분리주대규낙동류항생소내약궤제。방법수집래자6가의원적114주내배병사성ABA림상분리균주，PCR확증규낙동류항생소결합파기인（ gyrA、gyrB、parC화parE），병진행서렬측정，여삼고균주ATCC17978기인조진행비대，학정기규낙동내약결정구시부존재내약상관돌변；PCR확증9개질립개도적규낙동류내약기인[qnrA、qnrB、qnrC、qnrD、qnrS、qepA、aac（6′）-Ⅰb-cr、oqxA화oqxB]，병대양성확증산물진행측서이학정기인아형。결과절대부분균주（113/114，99．1％）적gyrA기인발생료Ser83 Leu돌변，기중67주균（67/114，58．8％）동시발생료parC기인적Ser80Leu돌변，이상량충돌변시상견적규낙동내약상관돌변。여표준균주진행비대，수시균주gyrB기인Arg393Ser、Arg393Cys、Thr401Ala、Pro406Ser、Val430Phe、Cys440Ser화Gly480Arg돌변솔분별위95．6％、0．9％、96．5％、96．5％、100％、96．5％화96．5％；parE기인재7개위점발생료동의돌변，돌변솔＞96％。83．3％（95/114）적균주중검출aac（6′）-Ⅰb기인，단불존재“cr”돌변，기여질립개도적규낙동류내약기인확증균위음성。결론해연구내배병사성ABA중미발현질립개도적규낙동내약기인，재gyrB화parE기인중발현적돌변가능여배병사성내약성무관，실험균주적배병사성내약성주요여염색체상적규낙동내약결정구GyrA-Ser83Leu화ParC-Ser80Leu량충돌변상관。
Objective To investigate the quinolone resistance determinants in ciprofloxacin-resistant Acinetobacter bau-mannii (ABA)clinical isolates.Methods One hundred and fourteen ciprofloxacin-resistant ABA strains were collected from six Chinese hospitals .The quinolone resistance determining region ( QRDR) of 4 target genes ( gyrA, gyrB, parC and parE) was amplified , sequenced and compared with the reference genome of ATCC 17978 to identify possible resistance-related mutations.Nine plasmid-mediated quinolone resistance (PMQR) genes (qnrA, qnrB, qnrC, qnrD, qnrS, qepA, aac(6′)-Ⅰb-cr, oqxA and oqxB) were also amplified, and the amplicons were then sequenced to determine their character-istics.Results Almost all isolates (113/114, 99.1%) harbored a substitution in codon 83 of gyrA gene, leading to a Ser83Leu mutation.Meanwhile,58.8%(67/114) of the isolates possessed dual mutations of GyrA-Ser83Leu and GyrA-Ser80Leu, which were known determinants for ciprofloxacin resistance .There were also multiple non-synonymous substitu-tions in gyrB, leading to Arg393Ser, Arg393Cys, Thr401Ala, Pro406Ser, Val430Phe, Cys440Ser and Gly480Arg muta-tions with prevalence rates of 95.6%, 0.9%, 96.5%, 96.5%, 100%, 96.5%and 96.5%,respectively.For parE, all the seven mutations were synonymous and found in more than 96%of the tested isolates.For PMQR genes, although 83.3%(95/114) of the isolates were positive for aac(6′)-Ⅰb, no"cr"mutations were identified.None of the other eight PMDR genes were found in our strain collection .Conclusion Although multiple mutations are identified in gyrB and parE, these mutations might be the characteristic SNP markers for specific clones , unlikely linked to quinolone resistance .No PMQR is found in the tested isolates.Mutations in chromosomal QRDR (GyrA-Ser83Leu and ParC-Ser80Leu) are the main determi-nants of ciprofloxacin resistance in our ABA collection .