發(fā)布時間：2019-03-09 17:24

【摘要】：犢牛腹瀉大腸桿菌病是由產(chǎn)腸毒素大腸桿菌所引起的,常常會導致犢牛劇烈腹瀉甚至死亡的一種犢牛腹瀉病,為奶牛業(yè)帶來了巨大的經(jīng)濟損失,同時也對人類的健康造成很大的威脅。臨床上濫用抗生素的現(xiàn)象越來越嚴重,導致耐藥菌株的增多以及耐藥譜的增寬,很多常用抗生素基本已經(jīng)完全失去效果。因此對全國各地的犢牛腹瀉大腸桿菌耐藥情況的調(diào)查分析,對預防和控制犢牛腹瀉病具有重要的意義。本研究主要包括大腸桿菌耐藥情況的調(diào)查和相關耐藥基因的檢測兩個部分。采用Kirby-Bauer紙片法,對分離自中國北方部分規(guī)�；膛龅�34株犢牛腹瀉大腸桿菌對22種常用抗生素的耐藥情況和多重耐藥進行了分析。結果為34株犢牛腹瀉大腸桿菌對強力霉素的耐藥率均達到了100%,耐藥率在80%以上的有5種,分別為氨芐西林、鏈霉素、阿奇霉素、強力霉素、復方新諾明。對呋喃妥因、頭孢塞肟、多粘菌素B的敏感率均在50%以上,對磷霉素的敏感率達到97.06%,因此對磷霉素最為敏感。本研究通過PCR方法對喹諾酮類、氨基糖苷類、β內(nèi)酰胺類、四環(huán)素類、氯霉素類、磺胺類的相關耐藥基因進行檢測。喹諾酮類檢測了GyrA、GyrB和ParC基因,其擴增陽性檢出率分別為70.59%、67.65%、61.76%,27株對喹諾酮類產(chǎn)生耐藥性,其中三種基因的陽性檢出率分別為74.07%、81.48%、66.67%。氨基糖苷類檢測了aadA、aadB和Aph(3’)-II基因,其擴增陽性檢出率分別為44.12%、23.53%、61.76%,33株對氨基糖苷類產(chǎn)生耐藥性,其中三種基因的陽性檢出率分別為42.42%、24.24%、72.72%,其中有一株對氨基糖苷類類沒有表現(xiàn)出耐藥表型的菌株檢出了aadA基因。β內(nèi)酰胺類檢測了blaTEM基因,其陽性檢出率為61.76%。氯霉素類檢測了floR、cat基因,其陽性檢出率分別為52.94%、32.35%,34株大腸桿菌中同時攜帶這兩種基因的檢出率為11.76%�；前奉悪z測了sul2、sul3基因,其陽性檢出率分別為52.94%、70.59%。四環(huán)素類檢測了tet(B)、tet(D)基因,其陽性檢出率分別為35.29%、26.47%�；谝陨蠙z測結果,北方部分奶牛場的犢牛腹瀉大腸桿菌大部分地區(qū)已經(jīng)產(chǎn)生了嚴重的耐藥性,并且已經(jīng)檢測了其相關的耐藥基因,同時試驗也證實了耐藥基因的傳播與擴散導致耐藥菌株數(shù)的上升,多重耐藥菌株的不可遏制給臨床治療帶來了很大的困難,本研究為北方地區(qū)臨床選擇藥物及如何合理使用抗生素提供了一定的依據(jù)。
[Abstract]:Calf diarrhoea colibacillosis is caused by enterotoxigenic Escherichia coli, which often leads to severe diarrhea and even death in calves. It has brought huge economic losses to the dairy industry. At the same time, it also poses a great threat to human health. The abuse of antibiotics in clinic is becoming more and more serious, which leads to the increase of drug-resistant strains and the widening of drug-resistance spectrum. Many commonly used antibiotics have lost their effect completely. Therefore, it is of great significance to investigate and analyze the drug resistance of Escherichia coli in calf diarrhea in different parts of the country in order to prevent and control calf diarrhoea. This study mainly includes two parts: the investigation of drug resistance of Escherichia coli and the detection of related drug resistance genes. The resistance and multi-drug resistance of 34 strains of diarrhea Escherichia coli isolated from large-scale dairy farms in northern China to 22 common antibiotics were analyzed by Kirby-Bauer paper method. The results showed that the resistance rate of 34 strains of Escherichia coli to doxycycline was 100%, and the drug resistance rate was more than 80%. They were ampicillin, streptomycin, azithromycin, doxycycline and compound Xinomin. The sensitive rates to furantoin, cefoxime and polymyxin B were all more than 50% and 97.06% to fosfomycin, so they were most sensitive to fosfomycin. In this study, quinolones, aminoglycosides, beta lactams, tetracyclines, chloramphenicol and sulfonamides were detected by PCR. The positive rates of GyrA,GyrB and ParC genes were 70.59%, 67.65%, 61.76%, respectively, and 27 strains were resistant to quinolones, among which the positive rates of three genes were 74.07%, and the positive rates were 70.59%, 67.65%, 61.76%, 74.07%, respectively. 81.48%, 66.67%. The positive rates of aadA,aadB and Aph (3')-II genes were 44.12%, 23.53%, 61.76%, respectively. 33 strains were resistant to aminoglycosides. The positive rates of three genes were 42.42%, 24.24% and 72.72%, respectively. Among them, one strain with no resistant phenotype to aminoglycosides detected the aadA gene, and 尾-lactams detected the blaTEM gene. The positive rate was 61.76%. The positive rate of floR,cat gene was 52.94%, 32.35% in chloramphenicol group and 11.76% in 34 strains of Escherichia coli, respectively. The positive rate of sul2,sul3 gene was 52.94% and 70.59% respectively. Tetracycline detected tet (B), tet (D) gene, the positive rates were 35.29% and 26.47%, respectively. Based on the above results, Escherichia coli from calf diarrhea in some dairy farms in the north has developed severe drug resistance in most areas, and its related drug resistance genes have been detected. At the same time, the experiment also confirmed that the spread and diffusion of drug-resistant genes led to the increase in the number of drug-resistant strains, and the uncontainment of multi-drug-resistant strains brought great difficulties to clinical treatment. This study provides a certain basis for clinical choice of drugs and rational use of antibiotics in northern China.
【學位授予單位】：吉林農(nóng)業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：S858.23

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