Division of Microbiology, National Centre for Toxicological Research, US FDA, Jefferson, AR, USA.
J Appl Microbiol. 2009 Feb;106(2):564-71. doi: 10.1111/j.1365-2672.2008.04026.x.
To isolate environmental bacteria capable of transforming fluoroquinolones to inactive molecules.
Bacteria were isolated from the aerobic liquor of a wastewater treatment plant on a medium containing norfloxacin (100 mg l(-1)). Twenty-two isolates were highly resistant (minimal inhibitory concentration: 6.25-200 microg ml(-1)) to five fluoroquinolones and six of them were positive by PCR amplification for the aminoglycoside resistance gene aac(6')-Ib. Of these, only Escherichia coli strain LR09 had the ciprofloxacin-acetylating variant gene aac(6')-Ib-cr; HPLC and mass spectrometry showed that this strain transformed both ciprofloxacin and norfloxacin by N-acetylation. This bacterium also had mutations in the quinolone-resistance determining regions of the gyrA and parC genes.
An E. coli isolate from wastewater, which possessed at least two distinct fluoroquinolone resistance mechanisms, inactivated ciprofloxacin and norfloxacin by N-acetylation.
This is the first report of N-acetylation of fluoroquinolones by an aac(6')-Ib-cr-containing bacterium from an environmental source.
分离能够将氟喹诺酮类药物转化为无活性分子的环境细菌。
从含有诺氟沙星（100mg l(-1)）的废水处理厂好氧液中分离出细菌。22 个分离株对五种氟喹诺酮类药物高度耐药（最小抑菌浓度：6.25-200μgml(-1))，其中 6 个通过氨基糖苷类耐药基因 aac(6')-Ib 的 PCR 扩增呈阳性。其中，只有大肠杆菌 LR09 株具有环丙沙星乙酰化变体基因 aac(6')-Ib-cr；HPLC 和质谱分析表明，该菌株通过 N-乙酰化作用转化环丙沙星和诺氟沙星。该细菌在 gyrA 和 parC 基因的喹诺酮耐药决定区也存在突变。
从废水中分离出的一株大肠杆菌，至少具有两种不同的氟喹诺酮类药物耐药机制，通过 N-乙酰化作用使环丙沙星和诺氟沙星失活。
这是首次报道环境来源的携带 aac(6')-Ib-cr 的细菌对氟喹诺酮类药物进行 N-乙酰化。
