大环内酯类药物次抑菌浓度诱导沙眼衣原体耐药的实验研究

发布时间：2018-04-05 16:40

本文选题：沙眼衣原体　切入点：大环内酯类　出处：《天津医科大学》2010年硕士论文

【摘要】： 目的：沙眼衣原体是一种严格的细胞内寄生的微生物,感染人体后可以引起结膜炎、性病性淋巴肉芽肿和泌尿系疾病。此外,持续沙眼衣原体感染可以导致不孕。有报道沙眼衣原体感染可能与是男性不育有关。众所周知,世界范围内D-K型沙眼衣原体血清变种(血清型)中是最常见的引起性传播疾病的微生物。最近的研究表明,沙眼衣原体E型感染精子后大大降低精子活力和生存能力,这可能导致男性的不孕。目前,治疗沙眼衣原体感染一线推荐使用的药物是四环素类和大环内酯类的阿奇霉素。大环内酯类药物已使用数十年,对大部分致病菌有效。抗生素在医学和畜牧业的广泛使用导致抗生素接二连三出现耐药,大环内酯类抗生素也不例外。各种微生物对大环内酯类抗生素耐药往往与核糖体蛋白基因的突变,特别是在L4及L22,以及在23S rRNA基因突变肽转移区有关。然而,沙眼衣原体临床耐药株报道相对较少。一种解释认为可能是因为生物体独特的发展周期。由于沙眼衣原体基因复制发生在感染的上皮细胞的包涵体中,从其他组织获得抗生素耐药基因是困难的。本文就沙眼衣原体对大环内酯类药物的可能分子耐药机制进行探讨。方法：目前有报道称磺胺类、青霉素类、利福平和氟喹诺酮类药物次抑菌浓度诱导沙眼衣原体选择性耐药株已在实验室获得。我们有理由认为次抑菌浓度的抗生素选择压力下可以导致点突变。13例沙眼衣原体临床敏感株经红霉素、阿奇霉素、交沙霉素次抑菌浓度诱导耐药后与未耐药之前的敏感株和标准株E-UW-5/Cx比较,检测基因23S rRNA和核糖体蛋白L4的位点突变。结果：耐药株显现出对红霉素、阿奇霉素和交沙霉素低耐药性,MIC较敏感株分别增加了16、16、8倍。药物敏感性结果显示相对于红霉素、阿奇霉素,沙眼衣原体治疗交沙霉素的易感性最好。敏感株和耐药株的L4的PCR扩增产物的序列均出现G274A、C276T、C339T、C466G位点突变,考虑与大环内酯类药物耐药无关。耐药株的23S rRNA基因PCR扩增产物中出现了A2057G、A2059G、G2093T和T2611C的突变。结论：沙眼衣原体对大环内酯类药物的耐药分子基础是23S rRNA基因的点突变。
[Abstract]:Objective: chlamydia trachomatis is a strict microorganism that can cause conjunctivitis, venereal lymphogranuloma and urinary diseases.In addition, persistent chlamydia trachomatis infection can lead to infertility.Chlamydia trachomatis infection has been reported to be related to male infertility.It is well known that D-K Chlamydia trachomatis serovariants (serotypes) are the most common bacteria causing sexually transmitted diseases (STDs) worldwide.Recent studies have shown that chlamydia trachomatis E-infected sperm significantly reduces sperm motility and viability, which may lead to infertility in men.Currently, the first recommended drug for treatment of chlamydia trachomatis infection is tetracycline and macrolide azithromycin.Macrolides have been used for decades and are effective against most pathogens.The widespread use of antibiotics in medicine and animal husbandry has led to the emergence of antibiotic resistance one after another, and macrolide antibiotics are no exception.Microbial resistance to macrolides is often associated with mutations in ribosomal protein genes, especially in L4 and L22, and in the 23s rRNA gene mutational peptide transfer region.However, relatively few clinical chlamydia trachomatis resistant strains have been reported.One explanation is that it may be because of the unique developmental cycle of organisms.Because Chlamydia trachomatis gene replication occurs in the inclusion bodies of infected epithelial cells, it is difficult to obtain antibiotic resistant genes from other tissues.The possible molecular resistance mechanism of chlamydia trachomatis to macrolides was discussed.Methods: it has been reported that the selective chlamydia trachomatis resistant strains induced by sulfanilamide penicillin rifampicin and fluoroquinolones have been obtained in laboratory.We have reason to think that the antibiotic selection pressure of secondary inhibitory concentration can lead to point mutation. 13 cases of Chlamydia trachomatis clinical sensitive strains were treated with erythromycin, azithromycin,The gene 23s rRNA and ribosomal protein L4 locus mutation were detected after induced drug resistance by josamycin subinhibitory concentration compared with sensitive and standard strains before drug resistance.Results: the low resistance MIC of the resistant strains to erythromycin, azithromycin and josamycin increased by 16 16 times, respectively.The results of drug sensitivity showed that compared with erythromycin, azithromycin and chlamydia trachomatis, the susceptibility to josamycin was the best.The sequence of PCR amplification products of L4 in both susceptible and resistant strains showed G274A C276TN C339TnC466G mutation, which was not related to macrolide resistance.The mutation of A2057GN, A2059GFG, G2093T and T2611C was found in the PCR products of 23s rRNA gene of drug-resistant strain.Conclusion: the molecular basis of chlamydia trachomatis resistance to macrolides is the point mutation of 23s rRNA gene.
【学位授予单位】：天津医科大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：R759

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