Mutations in the gyrA, parC, and mexR genes provide functional insights into the fluoroquinolone-resistant Pseudomonas aeruginosa isolated in Vietnam.
Mutations in the gyrA, parC, and mexR genes provide functional insights into the fluoroquinolone-resistant Pseudomonas aeruginosa isolated in Vietnam.
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DOI：
10.2147/idr.s147581
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发表时间：
2018
影响因子：
3.9
通讯作者：
Le DV
中科院分区：
文献类型：
--
作者：
Nguyen KV;Nguyen TV;Nguyen HTT;Le DV
铜绿假单胞菌对氟喹诺酮类药物的耐药机制多种多样。主要机制是改变打开DNA螺旋的两种酶的作用-DNA促旋酶（gyrA）和拓扑异构酶IV（parC）。此外，使MexAB-oprM泵（mexR）功能障碍的突变，导致其过度表达，也增强了对氟喹诺酮类药物的耐药性。在这项研究中，我们的目的是检测gyrA，parC和mexR基因的点突变，这些基因预计与2013-2016年在越南分离的141株铜绿假单胞菌耐氟喹诺酮类药物临床分离株中的氟喹诺酮类药物耐药相关。我们使用VITEK 2 Compact System检测了141株铜绿假单胞菌临床分离株中氟喹诺酮类抗生素的最低抑菌浓度（MIC），随后采用PCR法检测并克隆gyrA、parC和mexR的氟喹诺酮类耐药决定区（FRDR）。通过桑格测序分析点突变，并对141株临床分离株进行基因突变与表型耐药的相关性研究。耐氟喹诺酮类药物的突变主要有gyrA基因的Ile替换Thr 83和Met替换Thr 133，parC基因的Ser 87替换Leu，mexR基因的阻遏物Glu 126替换瓦尔。比较分析数据表明，gyrA和parC基因内的氨基酸改变与环丙沙星（CIP）和左氧氟沙星（LEV）的耐药性高度相关的分离株，而外排调节mexR基因的改变是不高度一致的耐药性在这些菌株。此外，铜绿假单胞菌的氟喹诺酮类耐药临床分离株主要分离自脓和痰标本。在铜绿假单胞菌临床分离株中，CIP和LEV的MIC与gyrA和parC基因的改变之间存在高度相关性。然而，mexR中发生的突变与细菌的抗生素耐药性没有高度相关性。
Pseudomonas aeruginosa has many mechanisms of resistance to fluoroquinolones. The main mechanism is to change the effect of two enzymes that open the DNA helix – the enzyme DNA gyrase (gyrA) and the topoisomerase IV (parC). In addition, mutations that render the MexAB-oprM pump (mexR) dysfunctional, leading to its overexpression, also enhance resistance to fluoroquinolones. In this study, we aim to detect point mutations of gyrA, parC, and mexR genes that are predicted to be associated with fluoroquinolone resistance in 141 fluoroquinolone-resistant clinical isolates of P. aeruginosa isolated in Vietnam during 2013–2016. We tested minimum inhibitory concentrations (MICs) of fluoroquinolone antibiotics in 141 clinical isolates of P. aeruginosa using the VITEK 2 Compact System, followed by PCR assay, to detect and clone the fluoroquinolone resistance-determining region (FRDR) of gyrA, parC, and mexR. Point mutations were analyzed through Sanger sequencing, and the correlation between genetic mutations and phenotypic resistance of 141 clinical isolates was undertaken. Fluoroquinolone-resistant substitution mutations such as Ile for Thr83 and Met for Thr133 in gyrA, Leu for Ser87 in parC, and Val for Glu126 in the repressor of mexR were mainly detected. Comparative analytical data indicated that amino acid alterations within the gyrA and parC genes are highly associated with resistance to ciprofloxacin (CIP) and levofloxacin (LEV) in the isolates, whereas alterations in the efflux regulatory mexR gene are not highly consistent with resistance in these isolates. Moreover, fluoroquinolone-resistant clinical isolates of P. aeruginosa were mainly isolated from pus and sputum specimens. In clinical isolates of P. aeruginosa, a high correlation was observed between MICs of CIP and LEV and alterations in gyrA and parC genes. However, mutations occurring in mexR did not highly correlate with the antibiotic resistance of the bacterium.