Nakase Keisuke, Sakuma Yui, Nakaminami Hidemasa, Noguchi Norihisa
Department of Microbiology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
Department of Microbiology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
Anaerobe. 2016 Dec;42:166-171. doi: 10.1016/j.anaerobe.2016.10.012. Epub 2016 Oct 26.
With the aim of elucidating the mechanisms of fluoroquinolones resistance in Propionibacterium acnes, we determined the susceptibility of fluoroquinolones in 211 isolates from patients with acne vulgaris. We identified five isolates (2.4%) with reduced susceptibility to nadifloxacin (minimum inhibitory concentration ≥ 4 μg/ml). Determination of the sequences of the DNA gyrase (gyrA and gyrB) and DNA topoisomerase (parC and parE) genes showed the amino acid substitutions Ser101Leu and Asp105Gly of GyrA in four and one of the isolates, respectively. In vitro mutation experiments showed that low-level fluoroquinolone-resistant mutants with the Ser101Leu or Asp105Gly substitution in GyrA could be obtained from selection with ciprofloxacin and levofloxacin. The pattern of substitution (Ser101Trp in GyrA) caused by nadifloxacin selection was different from that induced by the other fluoroquinolones. In the isolation of further high-level resistant mutants, acquisition of another amino acid substitution of GyrB in addition to those of GyrA was detected, but there were no substitutions of ParC and ParE. In addition, the mutant prevention concentration and mutation frequency of nadifloxacin were lowest among the tested fluoroquinolones. The growth of the Ser101Trp mutant was lower than that of the other mutants. Our findings suggest that the Ser101Trp mutant of P. acnes emerges rarely and disappears immediately, and the risk for the prevalence of fluoroquinolones-resistant P. acnes differs according to the GyrA mutation type. To our knowledge, this study is the first to demonstrate the mechanisms of resistance to fluoroquinolones in P. acnes.
为阐明痤疮丙酸杆菌对氟喹诺酮类药物耐药的机制，我们测定了211株寻常痤疮患者分离株对氟喹诺酮类药物的敏感性。我们鉴定出5株（2.4%）对那氟沙星敏感性降低的菌株（最低抑菌浓度≥4μg/ml）。对DNA回旋酶（gyrA和gyrB）和DNA拓扑异构酶（parC和parE）基因序列的测定显示，4株和1株分离株中GyrA分别出现了Ser101Leu和Asp105Gly的氨基酸替代。体外突变实验表明，通过环丙沙星和左氧氟沙星筛选可获得GyrA中具有Ser101Leu或Asp105Gly替代的低水平氟喹诺酮耐药突变体。那氟沙星筛选导致的替代模式（GyrA中的Ser101Trp）与其他氟喹诺酮类药物诱导的模式不同。在进一步分离高水平耐药突变体时，除了GyrA的替代外，还检测到了GyrB的另一个氨基酸替代，但ParC和ParE没有替代。此外，在测试的氟喹诺酮类药物中，那氟沙星的突变预防浓度和突变频率最低。Ser101Trp突变体的生长低于其他突变体。我们的研究结果表明，痤疮丙酸杆菌的Ser101Trp突变体很少出现且会立即消失，并且耐氟喹诺酮类痤疮丙酸杆菌流行的风险因GyrA突变类型而异。据我们所知，本研究首次证明了痤疮丙酸杆菌对氟喹诺酮类药物的耐药机制。
