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15株动物源性耐氟喹诺酮类药物大肠杆菌进行PCR检测、测序、WDNASIS软件分析gyrA基因中的氟喹诺酮耐药决定区(QRDR)、AcrA以及编码与质粒介导的氟喹诺酮类药物耐药机制相关的qnrA、qnrB、qnrS、qepA和aac(6′)-Ib-cr基因。结果表明,15株耐药菌中,QRDR基因在其编码第72、75、83位或第87位氨基酸均发生突变;AcrA基因未检测到氨基酸的突变;qnrS、qepA和aac(6′)-Ib-cr耐药基因阳性菌各检测到1株,序列分析表明不存在氨基酸突变。QRDR基因编码的氨基酸4个位点发生突变,其中Ser83→Leu和Asp87→Asn 2个基因的突变均与文献报道的突变相同,双突变的7个菌株均表现为高度耐氟喹诺酮类抗生素,表明gyrA基因为大肠杆菌耐氟喹诺酮类抗生素的一个重要机制。高度耐氟喹诺酮类抗生素的菌株中有2株没有检测到氨基酸突变的存在,但是aac-(6′)-Ib-cr基因和qnrS检测为阳性,表明质粒介导的喹诺酮类耐药也可单独导致菌株的耐药。存有一个菌株gyrA基因编码的氨基酸发生突变Ser83→Leu,AcrA基因和qnrA、qnrB、qnrS、qepA和aac(6′... 相似文献
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取临床分离的、对5种氟喹诺酮类药物（环丙沙星、氧氟沙星、恩诺沙星、单诺沙星和沙拉沙星）均耐药的9株鸡源性沙门氏菌耐药株,提取其染色体DNA。设计引物gyrAF和gyrAR、gyrBF和gyrBR,分别扩增菌株DNA旋转酶gyrA基因和gyrB基因的氟喹诺酮类耐药决定区（QRDR）,对PCR扩增产物进行测序及序列分析。与质控菌株相比,9株临床分离耐药株中只有菌株38和60的gyrA基因发生单碱基突变,菌株38的gyrA基因第371位碱基发生C→T突变,菌株60的gyrA基因第350位碱基发生A→C突变,两处突变均位于QRDR内,其余菌株的核苷酸未发生任何突变。菌株38的碱基突变导致gyrA基因第99位氨基酸发生R→C取代,即Arg→Cys;菌株60的碱基突变导致gyrA基因第92位氨基酸发生M→L取代,即Met→Leu。9株临床分离鸡源性沙门氏菌氟喹诺酮类耐药株gyrB基因QRDR的核苷酸序列与质控菌株完全相同;只有菌株42的gyrB基因第1592位碱基发生C→A突变,但其位于gyrB基因QRDR之外,且菌株42的gyrB基因的碱基突变并没有导致相应氨基酸的改变。上述结果提示,DNA旋转酶gyrA基因和gyrB基因QRDR突变可能并非沙门氏菌耐药性产生的主要原因。 相似文献
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猪源链球菌对环丙沙星耐药性与耐药基因突变的相关性研究 总被引：1，自引：0，他引：1
通过微量稀释法测定28株猪源链球菌对环丙沙星的MIC值,研究东北地区猪源链球菌对环丙沙星耐药性与parC、gyrA基因突变的相关性.通过PCR方法扩增parC和gyrA基因喹诺酮耐药决定区(QRDR)并测序分析;18株耐药菌在parC基因80位的突变(AGC→ATT)导致氨基酸Ser→Ile突变,11株高度耐药菌在gyrA基因81位的突变(CAG→)CAT、CTT或CTA)导致氨基酸Ser→Ile、Phe或Tyr的突变.当菌株对环丙沙星的MIC值≤1μ/mL时,parC和gyrA基因的QRDR区均未有突变;而当MIC ≥2μg/mL时,ParC的氨基酸发生了Ser80→Ile的突变,同时发生GyrA氨基酸Ser81突变的菌株,耐药水平很高.研究表明,环丙沙星低水平类耐药是由于拓扑异构酶Ⅳ改变引起,而高水平耐药是由拓扑异构酶Ⅳ、DNA旋转酶共同改变引起的.实验结果证明,在一定条件下,耐药性的高低与突变位点的多少成正比. 相似文献
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鸭疫里默氏菌的gyrA基因的检测与变异位点的分析 总被引：1，自引：0，他引：1
近年来，随着喹诺酮类药物的广泛应用，尤其是一些养殖场的盲目滥用和超量服用，导致耐药菌株不断出现。关于耐药的大肠埃希氏菌、金黄色葡萄球菌、粪肠球菌、铜绿假单胞菌等细菌在其螺旋酶gyrA基因的喹诺酮类药物决定区（QRDR）的突变热点已有很多报道，这些菌株的突变热点相对于大肠杆菌来说，发生在第83位和87位的氨基酸上。到目前为止，鸭疫里默氏菌螺旋酶gyrA基因还是未知的，其耐药基因的突变更没有报道。本试验测出了鸭疫里默氏菌gyrA的部分基因，找到了对喹诺酮类抗生素耐药菌株的基因突变热点和突变规律。为以后研究鸭疫里默氏菌对喹诺酮类抗生素耐药的分子机制提供了基础。 相似文献
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《中国家禽》2021,(12)
为研究肉鸡生产链中弯曲杆菌的流行规律,从广东省广州市、佛山市的家禽养殖场、屠宰场和市场中采集了1 414份样本,通过分离细菌、检测耐药性及耐药基因等方法分析该病的流行规律。结果显示:共分离出201株弯曲杆菌,阳性率为14.21%,且养殖场(25.1%)到屠宰场(11.9%)到市场(7.1%)的弯曲杆菌污染率呈现递减趋势;弯曲杆菌分离株对喹诺酮类和磺胺类药物具有高耐药率且喹诺酮类药物耐药菌株的gyrA基因QRDR区域发生了C257T的突变,突变率为100%;大环内酯类药物耐药菌株的23 S rRNA基因均发生了A2075G点突变。此外,大环内酯类耐药株的甲基化酶耐药基因ermB的携带率为52.38%,四环素类药物耐药株的tet(O)基因的携带率为97.37%。研究表明广东省部分地区禽源弯曲杆菌对喹诺酮类耐药率高且多重耐药情况普遍,提示加强禽源弯曲杆菌耐药基因的监测。 相似文献
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为了探讨金黄色葡萄球菌对氟喹诺酮耐药性与gyrA、gyrB突变的关系，本研究对氟喹诺酮敏感金黄色葡萄球菌进行耐药诱导，获得一系列不同氟喹诺酮耐药水平的人工诱导耐药菌，应用PCR扩增野生菌和人工诱导菌的gyrA、gyrB基因并测序，经核苷酸和氨基酸序列分析表明：氟喹诺酮耐药菌的gyrB基因无突变，氟喹诺酮耐药菌的gyrA有Ser85→Leu和Ser84→Pro的突变。实验结果表明：gyrA突变是金黄色葡萄球菌氟喹诺酮耐药水平增高的主要原因。 相似文献
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旨在了解猪链球菌对氟喹诺酮类药物耐药性与parC、gyrA基因突变的相关性,通过微量稀释法测定34株猪链球菌对4种氟喹诺酮类药物的MIC值,采用PCR方法扩增并测序分析了临床分离的猪链球菌对氟唪诺酮类约物10株耐药株和9株敏感株的parC和gyrA基因喹诺酮耐药决定区(QRDRs).在氟喹诺酮类药物耐药菌株parC基因QRDRs发生Ser79→Phe、Arg 87→Leu的氨基酸突变,在4株高度耐药菌株gyrA基因QRDRs发生Arg66→Ser,Ser81→Arg氨基酸突变;当菌株对氟喹诺酮类药物敏感时,parC和gyrA基因的QRDR区均未有突变;而当MIC≥32 μg·L-1 时,parC的氨基酸发生了 Ser79→Phe的突变,同时发生gyrA氨基酸Arg66→Ser,Set81→Arg突变.结果表明,猪链球菌对氟喹诺酮类药物低水平类耐药是由parC单一位点突变引起,而高水平耐药是由parC和gyrA双位点突变引起. 相似文献
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《动物医学进展》2020,(4)
为了解动物源大肠埃希菌对氟喹诺酮类药物的耐药情况及其与gyrA基因突变的联系,采用微量肉汤稀释法测定200株猪鸡源大肠埃希菌对恩诺沙星和氧氟沙星的最低抑菌浓度(MIC);对大肠埃希菌的gyrA基因片段进行PCR扩增,产物进行变性高效液相色谱(DHPLC)检测和序列测定。结果表明,200株动物源大肠埃希菌对恩诺沙星和氧氟沙星的耐药率分别为44.5%和41.0%;144株大肠埃希菌gyrA基因产物的DHPLC图谱有异常峰型,即核苷酸突变率为72.0%;测序证实gyrA基因存在5个突变位点,其中2个位点的突变可导致Ser83→Leu和Asp87→Asn/Tyr,突变率分别为54.0%和24.0%,其余3个位点为同义突变点;结合恩诺沙星耐药情况可知,敏感菌株gyrA基因的氨基酸突变率最低(18.5%),其次为中介菌株(56.5%),耐药菌株最高(78.6%),氧氟沙星测试结果与此趋势一致。由此可知动物源大肠埃希菌gyrA基因突变引起的氨基酸替代与氟喹诺酮耐药高度相关。 相似文献
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测定了痢疾杆菌福氏2a301株与喹诺酮类药物耐药性相关的gyrA基因和ParC基因的序列，并对其环丙沙星耐药诱变株的gyrA和ParC基因喹诺酮类药物耐药性决定区(QRDR)序列进行了测定分析。结果表明，痢疾杆菌福氏2a301株gyrA和ParC基因分别为2625bp和2256bp，环丙沙星诱导的耐药菌gyrA基因QRDR(245bp)发生氨基陵残基69—Ala→Val和87—Tyr→AsP改变，ParC基因QRDR(237b)发生氨基酸残基79—Ala→Asp、84—Ala→Glu和85—Pro→Ala改变。这一研究结果对认识痢疾杆菌喹诺酮类药物耐药性的分子机理具有重要意义。 相似文献
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探讨不同禽源大肠埃希菌中喹诺酮类药物的耐药情况及耐药基因gyrA的分布和突变特征。采用K-B药敏纸片法、gyrA基因的PCR扩增,对9株大肠埃希菌进行喹诺酮类药物试验,并将gyrA基因的PCR产物测序,对测序结果采用DNA MAN、DNA Star、MEGA6等软件分析。药敏试验结果表明,C1、C2、C3菌株对左氧沙星、氧氟沙星、环丙沙星、诺氟沙星敏感,D1、D2、D3、B1、B2和B3菌株对左氧沙星、氧氟沙星、环丙沙星、诺氟沙星均表现为耐药和中介;gyrA基因的测序结果表明,除B1菌株有1处核苷酸突变位点和B2菌株有14处核苷酸突变位点;B2菌株gyrA基因的氨基酸突变发生在87位Ile→Val替代、101位Leu→Met替代、102位Ala→Ser替代、129位Lys→Gln替代。9株禽源大肠埃希菌的同源性和进化树分析表明,不同禽源耐氟喹诺酮类药物的大肠埃希菌菌株中B2菌株gyrA基因与其他9株菌株相比,同源性在90%左右,进化树不在一个分支上,研究中的B2菌株将为大肠埃希菌的氟喹诺酮类耐药机制的研究提供候选菌株。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献