Effect of biofilm formation on antimicrobial tolerance of Flavobacterium psychrophilum

Treatment of bacterial fish diseases can be complicated by resistant bacterial biofilms harbouring pathogenic bacteria and causing recurrent exposure of fish to infections. In this study, the effect of biofilm formation on antimicrobial tolerance was examined using three bacterial isolates of the fish pathogen Flavobacterium psychrophilum and two antimicrobial agents, oxytetracycline and flumequine, commonly used in aquaculture. Planktonic and biofilm cells were exposed to a minimum inhibitory concentration (MIC), to a 3 × MIC concentration and to an environmental concentration level of each antimicrobial in 96-well microtitre plates after which growth on agar plates was measured. The type strain NCIMB1947 of F. psychrophilum was further used to study the development of antimicrobial resistance in biofilm cells. The results suggest that at high bacterial densities (>10(7) CFU mL(-1)), biofilm cells of F. psychrophilum are less susceptible to antimicrobial agents. Furthermore, the results imply that biofilm cells of F. psychrophilum may rapidly develop resistance to both oxytetracycline and flumequine if exposed to subinhibitory concentrations of these antimicrobials.     

高效液相色谱法测定氟甲喹可溶性粉含量

采用高效液相色谱法测定氟甲喹可溶性粉的含量,采用C 18 色谱柱(150 mm×4.6 mm,5μm),以乙腈-水-磷酸(35∶65∶0.5,V/V)为流动相,柱温25 ℃,流速1.0 mL/min,检测波长248 nm.方法的线性范围 100～400 μg/mL,线性方程A=2.455×104C 28 111,r=0.999 9,平均回收率100.3%,RSD= 0.74%.本法具有专属性,可将氟甲喹与已知的杂质进行有效分离.     

Flumequine in the Goat: Pharmacokinetics after Intravenous and Intramuscular Administration

The pharmacokinetics of flumequine, administered intravenously and intramuscularly at a single dose of 20 mg/kg, was investigated in healthy goats. After intravenous injection, flumequine distributed rapidly (t1/2alpha = 0.87+/-0.15 h) but was eliminated slowly (t1/2beta = 7.12+/-1.27 h); mean clearance (Cl) and volume of distribution (Vdss) were 0.32+/-0.03 (L/(h x kg) and 1.22+/-029 (L/kg), respectively. After intramuscular administration, the peakserum concentration (Cmax = 7.40+/-0.5 microg/ml) was reached in about 1.5 h (Tmax) and bioavailability was about 93%. Estimated flumequine serum levels following repeated intramuscular administration of the aqueous suspension used in the study (7.23+/-0.7 microg/ml and 4.82+/-0.47 microg/ml at intervals of 8 and 12 h, respectively) indicated that to maintain serum levels above MIC values for susceptible bacteria a dosage regimen of 20 mg/kg every 12 h is necessary by the intramuscular route.     

氟甲喹的波谱学数据与结构确证

建立了一种仪器分析技术确证氟甲喹化学结构的方法。采用紫外光谱(UV)、红外光谱(IR)、质谱、一维(1H、13C、DEPT)和二维(HSQC、HMBC、1H–1H COSY)核磁共振谱、热重分析(TGA)、差示扫描量热法(DSC)以及X—射线粉末衍射(PXRD)对氟甲喹进行结构分析。讨论了紫外和红外吸收特征峰,详细归属了所有的1H-NMR和13C-NMR信号,并对热分析(TGA/DSC)结果进行了解析,确定了与晶型相关的不同衍射角的特征衍射峰。以上研究结果确证了氟甲喹的化学结构。     

鸡蛋和牛奶中噁喹酸、氟甲喹残留的检测方法研究

建立了高效液相色谱-荧光检测器法测定鸡蛋和牛奶中噁喹酸和氟甲喹残留量的方法.用1％甲酸乙腈提取样品中噁喹酸和氟甲喹残留;HPLC条件:C18色谱柱,流动相为0.02 mol/L磷酸溶液-乙腈-四氢呋喃(68∶16∶16);检测波长:激发波长325 nm,发射波长369 nm.结果显示,噁喹酸和氟甲喹在3～500 ng/mL浓度范围内与峰面积呈良好的线性关系.在10 ～ 100 ng/g的浓度添加水平上,其回收率为73％ ～94％,批内、批间的相对标准偏差均小于12％.     

HPLC法测定鸡肉中氟甲喹残留量的测量不确定度评定

建立了高效液相色谱法(HPIC)测定鸡肉中氟甲喹残留量的测量不确定度评定的数学模型,对测量过程中的不确定度来源进行逐项分析与合成,得出了高效液相色谱法测定鸡肉中氟甲喹残留量的不确定度结果.     

高效液相色谱法测定鳗鱼中氟甲喹和喹酸的残留量

建立了高效液相色谱-荧光检测器法测定鳗鱼中氟甲喹和噁喹酸残留量的方法。用乙腈萃取鳗鱼样品中氟甲喹和噁喹酸残留物。色谱柱采用C8Luna,柱温为35℃,激发波长和发射波长分别为312nm和369nm,流动相为0．01mol/L草酸：乙腈=65：35（V/V）。氟甲喹和噁喹酸标准曲线在线性范围1～100ng/mL时呈良好线性关系。对带皮的鳗鱼肉进行3种浓度的回收率测定。实验结果表明,回收率80％～110％,变异系数≤10％。氟甲喹的检测限为2．5μg／kg,定量下限为5μg／kg;噁喹酸的检测限为1μg／kg,定量下限为2μg／kg。整个提取过程步骤简单,易于操作,可以满足世界各国目前对出口水产品检测的限量要求。     

A pharmacokinetic study of flumequine in sea bass, Dicentrarchus labrax (L.), after a single intravascular injection

The pharmacokinetic properties of flumequine following a single intravascular injection (10 mg kg^–1 fish) were studied in sea bass, Dicentrarchus labrax (L.), 120 g held at 18 °C. The absorption half life ( t _1/2α) and the elimination half life ( t _1/2β) of the drug were calculated to be 1.05 and 10.71 h, respectively. Tissue penetration of flumequine seemed to be moderate because both the apparent volume of distribution of the drug at steady-state ( V _d(ss)) and the extensive apparent volume of the central compartment ( V _c) were found to be small (1.51 and 0.626 L kg^–1). The mean residence time ( MRT ) was short (09.73 h) and the total clearance (CL_T) of the drug was rapid (0.156 L kg^–1 h^–1).     

氟甲喹对异育银鲫细胞色素CYP450主要药酶的影响

在分析了氟甲喹腹腔注射后对异育银鲫(Carassius auratus gibelio)主要药酶活性影响的基础上,从蛋白表达和mRNA转录水平探究了氟甲喹对CYP1A(EROD)的诱导机制.以氟甲喹剂量35 mg/kg一次性腹腔注射异育银鲫24 h后,肝微粒体的7-乙氧基异吩唑酮-O-脱乙基酶(EROD)活性为54.33 pmol/(mg·min).显著高于对照组的34.00pmol/(mg·min)(P<0.01),而红霉索-N-脱甲基酶(ERND)[177.98 pmol/(mg·min)]、氨基比林-N-脱甲基酶(APD)[934.40 pmol/(mg·min)]及7-乙氧基香豆素-O-脱乙基酶(ECOD)[9.84 pmol/(mg·min)]与对照组[分别为140.90pmol/(mg·min)]、850.71 pmol/(mg·min)和8.93 pmol/(mg·min)]相比无显著性差异;除肾组织中ERND活性高于肝脏外,其他CYP亚型药酶活性(APD、EROD和ECOD)均以肝组织中最高.Western-blotting印迹表明,实验组肝脏中CYP1A蛋白含量明显高于对照组,与酶活(EROD)相符合;而肾、肠中没有检测到特异性条带.半定量RT-PCR结果显示,CYPiAmRNA在肝、肾和肠均有表达,但实验组与对照组并无明显差异.体外实验中,不同浓度的氟甲喹与微粒体共孵育,未见EROD活性与浓度、时间的依赖关系.综上推测,氟甲喹对鲫鱼肝CYP1A的诱导是在翻译后水平,可能是加强蛋白的稳定性.本研究旨在为氟甲喹在鱼类中的合理应用提供科学依据.