【摘要】：大腸桿菌對(duì)β-內(nèi)酰胺類抗生素的耐藥性發(fā)展迅速,細(xì)菌可以產(chǎn)生多種耐藥機(jī)制,其中PBP3是β-內(nèi)酰胺類抗生素主要作用靶位點(diǎn),靶位蛋白的任何改變都能使大腸桿菌對(duì)β-內(nèi)酰胺類抗生素產(chǎn)生耐藥。整合子在水平傳遞細(xì)菌耐藥性方面發(fā)揮重要作用,是細(xì)菌多重耐藥性形成的主要手段,大部分耐藥性的水平傳播都是由Ⅰ類整合子介導(dǎo)的。 本研究選取苦豆子堿作為受試藥物,分析臨床分離菌株對(duì)苦豆子堿及β-內(nèi)酰胺類抗生素的敏感性,進(jìn)一步用苦豆子堿亞抑菌濃度作用于穩(wěn)定表達(dá)PBP3的耐藥菌株,研究苦豆子堿對(duì)PBP3基因序列及mRNA表達(dá)量的影響。結(jié)果表明,8mg/mL的苦豆子堿作用于產(chǎn)PBP3耐藥菌株36h利48h后,能使菌株對(duì)抗生素的敏感性發(fā)生變化,MIC值下降了8-16倍；苦豆子堿與頭孢噻肟、頭孢曲松體外聯(lián)合對(duì)大腸桿菌具有協(xié)同作用；苦豆子堿雖未能改變PBP3基因序列；但作用后耐藥菌株的PBP3mRNA表達(dá)量下調(diào),從而使耐藥性大腸桿菌恢復(fù)相對(duì)敏感性。 對(duì)臨床分離的大腸桿菌進(jìn)行Ⅰ類整合子的分布特性研究。用苦豆子堿亞抑菌濃度作用于Ⅰ類整合子中攜帶基因盒的陽性菌株,研究藥物作用前后對(duì)1類整合子的影響。結(jié)果表明,臨床分離菌株均呈現(xiàn)多重耐藥性,耐藥種類集中在7-12種抗生素之間；整合酶基因(intI1)檢出率為66.7%,基因盒檢出率為75%,其中共檢測到兩種基因盒類型,苦豆子堿亞抑菌濃度作用于基因盒陽性菌株,導(dǎo)致其耐藥程度和耐藥種類均發(fā)生了改變；將藥物處理后的基因盒陽性菌株與標(biāo)準(zhǔn)株進(jìn)行水平培養(yǎng),研究苦豆子堿對(duì)耐藥性水平傳播的影響。結(jié)果表明,豆子堿亞抑菌濃度能夠減弱耐藥性傳播的程度,初步表明苦豆子堿在延緩Ⅰ類整合子散播方面發(fā)揮了積極作用。
[Abstract]:The drug resistance of Escherichia coli to 尾 -lactam antibiotics develops rapidly, and bacteria can produce a variety of drug resistance mechanisms, among which PBP3 is the main target of 尾 -lactam antibiotics. Any changes in target proteins can make Escherichia coli resistant to 尾-lactam antibiotics. Integron plays an important role in the horizontal transmission of bacterial drug resistance and is the main method for the formation of multidrug resistance of bacteria. Most of the horizontal transmission of drug resistance is mediated by class I integron. In this study, the sensitivity of clinical isolates to kaliurine and 尾 -lactam antibiotics was analyzed, and the drug resistant strains expressing PBP3 stably were further treated with subinhibitory concentration of kaliudine. Objective: to study the effect of Sophorin on PBP3 gene sequence and mRNA expression. The results showed that the sensitivity of 8mg/mL to antibiotics was changed after treatment of PBP3 resistant strains for 36 h and 48 h, and the MIC value decreased by 8-16 times. The combination of balsicine, cefotaxime and ceftriaxone has synergistic effect on Escherichia coli in vitro. However, the expression of PBP3mRNA was down-regulated in drug-resistant strains, so that the relative sensitivity of drug-resistant Escherichia coli was restored. The distribution of class I integron in clinical isolated Escherichia coli was studied. The effect of subinhibitory concentration of Sophora alopecuroides on class I integron carrying gene cassette positive strains was studied before and after treatment. The results showed that the clinical isolates showed multidrug resistance, and the drug resistance was concentrated in 7-12 antibiotics. The detectable rate of integrase gene (intI1) and gene box was 66.7% and 75% respectively. Two types of cassette were detected. As a result, the degree of drug resistance and the types of drug resistance have been changed. In order to study the effect of Sophorin on the transmission of drug resistance, the gene cassette positive strain and standard strain were cultured at different levels. The results showed that the subinhibitory concentration of soybean alkaloids could reduce the spread of drug resistance, which indicated that kaliuridine played an active role in delaying the dissemination of class I integron.
【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：R3416

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