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替加环素是治疗多重耐药肺炎克雷伯氏菌感染的为数不多的抗菌药物之一,但替加环素耐药肺炎克雷伯氏菌的出现给临床治疗带来了严重威胁。本实验从临床分离到1株替加环素耐药肺炎克雷伯氏菌,电转化实验获得了一个对替加环素耐药的质粒,功能性分析发现该质粒中的tet(A)基因发生了双移码突变,且药敏实验证实这些突变可单独使替加环素的MIC值增加8倍,米诺环素和四环素的MIC值增加128倍。研究证实,质粒介导的tet(A)突变体可导致肺炎克雷伯氏菌对替加环素耐药,扩宽了对肺炎克雷伯氏菌替加环素耐药机制的认识,并为该类型耐药基因在革兰氏阴性菌中的扩散控制提供了依据。 相似文献
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替加环素作为新型四环素类抗生素，是治疗产碳青霉烯酶多重耐药肠杆菌感染的最后一道防线之一。近年来，替加环素耐药菌株的出现严重限制了替加环素的临床使用。最初认为替加环素的耐药机制是由染色体编码的外排泵介导，不能通过水平转移导致菌株耐药。随着研究的深入，发现质粒上的某些外排泵突变或高表达也可导致菌株替加环素敏感性降低。最近报道质粒介导的tet（X）变异体能够使菌株对替加环素产生高水平耐药，并通过可接合性质粒在不同种属细菌间传播。文章通过介绍细菌染色体介导替加环素耐药机制以及质粒介导的替加环素耐药机制，阐述了高水平替加环素耐药基因tet（X）变异体的流行情况和传播机制，并对动物源菌株出现高水平替加环素耐药基因tet（X）变异体提出合理性解释，旨在为相关科研人员和临床工作者提供参考。 相似文献
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There is limited information on antibiotic resistance determinants present in bacteria of aquaculture origin in Australia. The presence of integron and other resistance determinants was investigated in 90 Aeromonas isolates derived from nine freshwater trout farms in Victoria (Australia). Polymerase chain reaction was carried out for the detection of integrase genes Int1, Int2 and Int3, gene cassette array, integron‐associated aadA, sul1 and qac1 genes, streptomycin resistance genes strA‐strB, β‐lactamase resistance genes blaTEM and blaSHV, and tetracycline resistance genes tetA‐E and tetM. Clonal analysis was performed by pulsed‐field gel electrophoresis (PFGE). Class 1 integrons were detected in 28/90 (31%) and class 2 and class 3 in none of the strains, aadA gene in 19/27 (70%) streptomycin‐resistant strains, sul1 in 13/15 (86.7%) sulphonamide‐resistant strains and qac1 gene in 8/28 (28.6%) integron‐bearing strains. Five strains from two different farms carried gene cassettes of 1000 bp each containing the aadA2 gene and PFGE analysis revealed genetic relatedness. tetC was detected in all and tetA in 9/18 (50%) tetracycline‐resistant strains. The strA‐strB, blaTEM or blaSHV genes were not detected in any of the strains. Aeromonas spp. carrying integrons and other resistance genes are present in farm‐raised fish and sediments even though no antibiotics were licensed for use in Australian aquaculture at the time of the study. 相似文献
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为了解副猪嗜血杆菌江西株的药物敏感性及其耐药基因,本实验采用K-B法测定分离株对57种药物的敏感性,结果显示20株副猪嗜血杆菌均对阿洛西林和万古霉素敏感,80％及以上的分离株对氨苄西林\舒巴坦、阿莫西林\棒酸等高度敏感.但分离株对恩诺沙星、氨曲南、四环素等的耐受性较强,某些菌株对多种药物具有抗性,其中6株菌能够耐受5种药物,5株菌能够耐受12种药物,3株菌能够耐受13种药物,甚至有2株菌能够耐受多达22种药物.将江西分离株的药物敏感性结果与其它国家或地区以及不同时间分离菌株的结果相比较表明,不同地区及不同时间段分离的菌株药物敏感性存在较大差异.为探索副猪嗜血杆菌耐药的分子机制,本研究设计引物并建立了检测四环素耐药基因tet(B)的PCR方法.运用所建立的方法检测江西株tet(B)基因,在15株四环素耐药菌株中检测出其中9株菌存在该基因,推测tet(B)可能是介导该菌对四环素耐药的主要分子机制之一. 相似文献
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WANG Liangliang WANG Qianqian ZHOU Bolun JIA Yixin WU Hua YUAN Li HU Gongzheng HE Dandan 《中国畜牧兽医》2007,47(9):3022-3029
Tigecycline,as a new tetracycline antibiotic,is one of the last lines of defense against carbapenems-producing enterobacter multidrug-resistant infections.In recent years,the emergence of tigecycline-resistant strains has severely restricted the clinical use of tigecycline.It was originally believed that the resistance mechanism of tigecycline was mediated by the efflux pump encoded by the chromosome,which could not lead to drug resistance by horizontal transfer.With the deepening of research,it was found that some efflux pump mutations or high expression on the plasmid could also cause the strain's tigecycline sensitivity to decrease.Recently,it has been reported that the plasmid-mediated tet(X) variant can make the strain highly resistant to tigecycline,and can be spread among different species of bacteria through adaptable plasmids.This article described the prevalence and transmission mechanism of high-level tigecycline resistance gene tet(X) variants by introducing bacterial chromosome-mediated tigecycline resistance mechanisms and plasmid-mediated tigecycline resistance mechanisms,and provided a reasonable explanation for the high-level variant of the tigecycline resistance gene tet(X) in animal-derived strains,aiming to provide reference for relevant scientific researchers and clinical workers. 相似文献
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