BMC MICROBIOLOGY
·
2019
·Vol. 19
·期 1
·1-8
·
IF 3.287
Zhu Dekang,Zheng Mingyu,Xu Jinge,Wang Mingshu,Jia Renyong,Chen Shun,Liu Mafeng,Zhao Xinxin,Yang Qiao,Wu Ying,Zhang Shaqiu,Huang Juan,Liu Yunya,Zhang Ling,Yu Yanling,Pan Leichang,Chen Xiaoyue,Cheng Anchun
Background Riemerella anatipestifer is one of the most serious infectious disease-causing pathogens in the duck industry. Drug administration is an important method for prevention and treatment of infection in duck production, leading to widespread drug resistance in R. anatipestifer . Methods For a total of 162 isolates of R. anatipestifer, the MICs were determined for a quinolone antimicrobial agent, namely, nalidixic acid, and three fluoroquinolones, namely, ciprofloxacin, enrofloxacin and ofloxacin. The gyr A, par C, and par E gene fragments were amplified by PCR to identify the mutation sites in these strains. Site-directed mutants with mutations that were detected at a high frequency in vivo were constructed (hereafter referred to as site-directed in vivo mutants), and the MICs of these four drugs for these strains were determined. Results In total, 100, 97.8, 99.3 and 97.8% of the 137 R. anatipestifer strains isolated between 2013 and 2018 showed resistance to nalidixic acid, ciprofloxacin, enrofloxacin, and ofloxacin, respectively. The high-frequency mutation sites were detected in a total of 162 R. anatipestifer strains , such as Ser83Ile and Ser83Arg, which are two types of substitution mutations of amino acid 83 in GyrA; Val799Ala and Ile811Val in ParC; and Val357Ile, His358Tyr, and Arg541Lys in ParE. MIC analysis results for the site-directed in vivo mutants showed that the strains with only the Ser83Ile mutation in GyrA exhibited an 8–16-fold increase in MIC values, and all mutants showed resistance to ampicillin and ceftiofur. Conclusions The resistance of R. anatipestifer to quinolone agents is a serious problem. Amino acid 83 in GyrA is the major target mutation site for the fluoroquinolone resistance mechanism of R. anatipestifer .
研究领域:
兽医学
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微生物学
·
分子生物学
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2025
·
IF 3.9
Hongbin Yang,Haocong Li,Haizhuang Jiang,Yubin Zhang,Luyao Xing,Xin Kang,Huazheng Wang,Shuhe Zhang,Haobin Shi,Wanli Kang
Nanopolymer microspheres have been widely studied in the development of low-permeability reservoirs as an effective material to improve foam stability. However, there are few studies on the foam stability mechanism of nanopolymer microspheres. In this work, the effect of surface hydrophobicity of fluorescent nanopolymer microspheres PARC(Flu-Ac) on the stability of CO2 foam was investigated by using foam performance as an evaluation index. The mechanism of foam stabilization by PARC(Flu-Ac) with different degrees of hydrophobicity was clarified by studying the drainage rate, micromorphology, interfacial rheology of foam, and adsorption behavior of microspheres on the foam liquid film. The results show that PARC(Flu-Ac)-5 microspheres with neutral wettability have the best foam stabilization effect. At 94 °C, the foam volume of CO2 foam is 630 mL and the foam half-life is 30.12 min. PARC(Flu-Ac)-5 microspheres have a high desorption energy and can stably adsorb at the gas–liquid interface to form a solid layer. The microspheres improve the mechanical strength of the foam and reduce the direct contact of the fluid, thus providing space resistance for thinning the liquid film and the diffusion of gas between bubbles. In addition, the microspheres can slow the thinning rate of the liquid film through the release of free water. The stability of the foam is significantly improved. This study further clarifies the enhancement mechanism of nanopolymer microspheres on the stability of CO2 foam, which has excellent guiding significance for the application of CO2 foam in low-permeability oil fields.
研究领域:
石油工程
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材料科学
·
界面化学
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产品关联
DOI
PubMed
高影响因子
FOLIA MICROBIOLOGICA
·
2015
·Vol. 61
·期 3
·249-253
·
IF 1
Hu Ruixue,Du Na,Chen Nan,Lin Li,Zhai Yanhua,Gu Zemao
The mechanisms of resistance to levofloxacin for Aeromonas hydrophila isolated from diseased fish and selected in vitro were examined in this study. Levofloxacin-resistant mutants were obtained by selection of A. hydrophila in vitro. The quinolone resistance-determining regions (QRDRs) of the gyrA and parC genes were sequenced in Lev R strains and reverse mutation strains. All Lev R strains carried a point mutation at codon 83 (Ser → Ile), and one strain (25 %) harbored a mutation at position 92 (Leu → Met) in the GyrA-QRDR. After being transferred in a levofloxacin-free medium, one strain of the mutants was successfully reversed and the reversion was related with mutations o f GyrA-QRDR at positions 81 (Gly → Asp) and 83 (Ile → Ser). No amino acid alteration was found in the ParC-QRDR. In addition, the minimum inhibitory concentration (MIC) of levofloxacin for the mutants was lower in the presence of reserpine, and all mutants were also resistant to some of the other quinolones. It was found that the mechanism of levofloxacin resistance of A. hydrophila selected in vitro was related to gyrA of type II topoisomerase, and an efflux mechanism was involved in the resistance as well.
研究领域:
微生物学
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分子生物学
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药理学
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水产病害防治
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抗菌药物耐药性
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Changwei Niu,Bing Wang,Yueyue Wang,Zichao Wang
The investigation focused on the removal of antibiotic resistance genes from wastewater using ferrate treatment at various sulfite concentrations. As the sulfite concentration increased from 0 to 28.5 mg/L, the total DNA removal rate treated by 10 mg/L ferrate increased from 71.45% to 96.48%. The antibiotic resistance genes , save our souls genes and class I integron abundance reduction treated by ferrate ranged from 0.02 log to 1.66 log copies/ml at different sulfite concentrations, and the antibiotic resistance gene parC removal was enhanced as the sulfite addition. When the sulfite concentration reached to 28.5 mg/L, the catalase and superoxide dismutase levels were decreased by 21.57% and 10.04%, respectively, while the reactive oxygen species and lactate dehydrogenase levels were increased by 75.34% and 28.67%, respectively, compared to those in the wastewater treated by alone ferrate without sulfite. In the coupled ferrate (10 mg/L) and sulfite (28.5 mg/L) system, sulfate radicals and hydroxyl radicals were the main contributors to the DNA removals, and their contribution rates were 51.99% and 28.95%, respectively. The antibiotic resistance genes and save our souls genes hosts changes showed microbial community significantly affected the DNA removal. This study offers novel comprehensions on the antibiotic resistance genes removal from the wastewater by the combined ferrate and sulfite.
研究领域:
环境科学
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水处理
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微生物学
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生物技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）