Contribution of Topoisomerase IV Mutation to Quinolone Resistance in Mycoplasma genitalium
Contribution of Topoisomerase IV Mutation to Quinolone Resistance in Mycoplasma genitalium
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DOI：
10.1128/aac.01956-12
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发表时间：
2013-04-01
影响因子：
4.9
通讯作者：
Deguchi, Takashi
中科院分区：
文献类型：
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作者：
Yamaguchi, Yuko;Takei, Masaya;Deguchi, Takashi
由于体外培养的困难，特别是临床分离株，生殖支原体喹诺酮类药物耐药的机制仍然知之甚少。在这项研究中，为了证实拓扑异构酶突变与喹诺酮类药物敏感性之间的关系，我们选择了可培养型菌株ATCC 33530作为环丙沙星耐药突变株。序列分析显示，突变菌株在拓扑异构酶IV中存在突变：ParC中的Gly81Cys， ParC中的Pro261Thr或ParE中的Asn466Lys。所有喹诺酮类药物对突变株的mic均比对野生株高2 ~ 16倍。未观察到与大环内酯类或四环素类交叉耐药。我们测定了喹诺酮类药物对DNA旋切酶和拓扑异构酶IV的抑制活性，以探讨其抗菌敏感性与对喹诺酮类药物主要靶酶的抑制活性之间的关系。此外，通过酶分析，我们证实了位于ParC喹诺酮类药物耐药决定区（QRDR）的Gly81Cys与喹诺酮类药物耐药有关。这是首次在体外分离出含有parC或parE基因取代的生殖支原体抗喹诺酮突变株，并测定其对纯化的生殖支原体拓扑异构酶的抑制活性。
The mechanism of quinolone resistance in Mycoplasma genitalium remains poorly understood due to difficulties with in vitro culture, especially of clinical isolates. In this study, to confirm the association between mutations in topoisomerases and antimicrobial susceptibilities to quinolones, ciprofloxacin-resistant mutant strains were selected using the cultivable type strain ATCC 33530. Sequence analysis revealed that the mutant strains harbored mutations in topoisomerase IV: Gly81Cys in ParC, Pro261Thr in ParC, or Asn466Lys in ParE. The MICs of all quinolones tested against the mutant strains were 2- to 16-fold higher than those against the wild-type strain. No cross-resistance was observed with macrolides or tetracyclines. We determined the inhibitory activities of quinolones against DNA gyrase and topoisomerase IV in order to investigate the correlation between antimicrobial susceptibility and inhibitory activity against the target enzymes, considered the primary targets of quinolones. Furthermore, using enzymatic analysis, we confirmed that Gly81Cys in the ParC quinolone resistance-determining region (QRDR) contributed to quinolone resistance. This is the first study to isolate quinolone-resistant mutant strains of M. genitalium harboring substitutions in the parC or parE gene in vitro and to measure the inhibitory activities against the purified topoisomerases of M. genitalium.