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Development of Quinolone resistance and prevalence of different virulence genes among Shigella flexneri and Shigella dysenteriae in environmental water samples
Letters in Applied Microbiology ( IF 2.0 ) Pub Date : 2020-01-10 , DOI: 10.1111/lam.13262
B Roy 1 , S K Tousif Ahamed 1 , B Bandyopadhyay 2 , N Giri 1
Affiliation  

The purpose of this study was to find out the mechanism of quinolone resistance in Shigella sp. isolated from environmental water samples from various parts of Kolkata, India. Out of 196 Shigella sp. isolated from 2014 to 2017, we selected 32 Shigella isolates for antimicrobial susceptibility tests. The minimum inhibitory concentrations (MIC) for quinolones ranged from 30 to 50 μg ml−1 for ofloxacin, 5–20 μg ml−1 for ciprofloxacin and 20–30 μg ml−1 for norfloxacin. A few amino acid changes were found in quinolone resistance determining region (QRDR) of gyrA. Mutations in gyrA lead to a higher increment of MIC of quinolones. Among the plasmid‐mediated (PMQR) quinolone resistance genes investigated, qnrB and aac(6')‐lb‐cr genes were found in all isolates. qnrA and qnrS were found in 25% and 62% of the isolates, respectively. ipaH gene was found in all of the isolates followed by the presence of other virulence genes ial, sen and stx1. Almost all the isolates having high MICs showed efflux pump activity in drug accumulation assay. All the mechanisms may or may not be present in a single strain. Several types of efflux pumps, presence of PMQR genes and mutations in drug target site of QRDR region may play the crucial role for resistance in our isolates.

中文翻译:

环境水样中福氏志贺菌和痢疾志贺菌中喹诺酮类抗性的发展和不同毒力基因的流行

本研究的目的是找出志贺氏菌对喹诺酮类药物的耐药机制。从印度加尔各答各地的环境水样中分离出来。在 196 种志贺氏菌中。从 2014 年到 2017 年,我们选择了 32 株志贺氏菌分离株进行抗菌药敏试验。喹诺酮类药物的最低抑菌浓度 (MIC) 范围为氧氟沙星 30 至 50 μg ml-1、环丙沙星 5-20 μg ml-1 和诺氟沙星 20-30 μg ml-1。在gyrA的喹诺酮耐药决定区(QRDR)中发现了一些氨基酸变化。gyrA 的突变导致喹诺酮类药物的 MIC 增加。在研究的质粒介导 (PMQR) 喹诺酮抗性基因中,在所有分离株中都发现了 qnrB 和 aac(6')-lb-cr 基因。qnrA 和 qnrS 分别在 25% 和 62% 的分离株中被发现。在所有分离株中都发现了 ipaH 基因,随后存在其他毒力基因 ial、sen 和 stx1。几乎所有具有高 MIC 的分离株在药物积累试验中都显示出外排泵活性。所有机制可能存在也可能不存在于单一菌株中。几种类型的外排泵、PMQR 基因的存在和 QRDR 区域药物靶点的突变可能对我们分离株的耐药性起关键作用。
更新日期:2020-01-10
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