【摘要】：金黃色葡萄球菌、鏈球菌和大腸桿菌是引起奶牛乳房炎的主要致病菌,而表皮葡萄球菌(Staphylococcus epidermidis,Se)被認為致病能力弱的條件致病菌,一般不引起奶牛乳房炎疾病的爆發(fā)。隨著研究的深入,發(fā)現(xiàn)表皮葡萄球菌極易在奶牛乳房環(huán)境中形成生物被膜,形成的生物被膜是金黃色葡萄球菌耐藥株的儲備庫,這些生物特點導致細菌耐藥性上升并呈現(xiàn)多重藥耐藥性特征。研究表明,細菌整合子系統(tǒng)在細菌耐藥性形成過程中扮演著重要的角色,它在整合酶的介導下可以直接捕獲外界耐藥基因,使耐藥基因轉(zhuǎn)移擴散致使多種類型的耐藥基因盒產(chǎn)生,耐藥基因盒的表達導致細菌多重耐藥性的形成。鑒于整合子在細菌耐藥性形成過程中的重要作用,研究菌株整合子與耐藥性關系以及藥物對其作用特點,具有重要的理論和應用價值。本研究首先通過藥理學和分子生物學手段對分離的臨床型奶牛乳房炎Se進行耐藥性和整合子分布特點分析,深入探討整合子與Se耐藥相關性。分析發(fā)現(xiàn),臨床分離的Se對臨床常用抗菌藥物的耐藥率為16.7%-100%,耐藥譜廣,呈多重耐藥的特點,所有分離株對青霉素的耐藥率最高；通過對細菌整合子流行特征研究,Ⅰ類整合子的檢出率為60%,Ⅱ類整合子的檢出率為16.7%,菌株中未檢查出Ⅲ類整合子。其中產(chǎn)膜Se中Ⅰ類整合子檢出率為71.4%,不產(chǎn)膜Se中Ⅰ類整合子的檢出率為56.5%。且在Se中,Ⅰ類整合子陽性菌株的耐藥率大于陰性菌株。從結(jié)果中可以看出Se中Ⅰ類整合子的檢出率最高,并且和Se的耐藥性有一定相關性；在含有Ⅰ類整合子的Se中耐藥基因盒的檢出率為77.8%,并發(fā)現(xiàn)每個耐藥基因盒至少攜帶兩個耐藥基因,其中氨基糖苷乙酰轉(zhuǎn)移酶、二氫葉酸還原酶、氯霉素乙�；D(zhuǎn)移酶是最常見的耐藥基因。在Se中,Ⅰ類整合子攜帶的基因盒陽性菌株耐藥種數(shù)高于基因盒陰性菌株,說明整合子攜帶的耐藥基因盒與細菌產(chǎn)生多重耐藥性有密切關聯(lián)。同時研究了生物被膜菌和浮游菌中Ⅰ類整合酶基因的表達量,以及藥物對Ⅰ類整合酶基因表達量的影響。結(jié)果表明,生物被膜菌和浮游菌中均有Ⅰ類整合酶基因的表達,且生物被膜菌Ⅰ類整合酶基因的表達量均高于浮游菌,隨著生物被膜的不斷加厚Ⅰ類整合酶基因的表達量也不斷升高。生物被膜密度的增大,可能會影響整合子捕獲耐藥基因的頻率,有利于耐藥基因的擴散。苦參堿對產(chǎn)膜Se的MIC高于或等于不產(chǎn)膜Se的MIC,并且苦參堿對Se生物被膜有抑制作用�？鄥A對Se的生物被膜菌和浮游菌兩種生長狀態(tài)下的Ⅰ類整合酶基因有調(diào)控作用,可以下調(diào)Ⅰ類整合酶基因的表達量,其中對浮游菌生長狀態(tài)下Ⅰ類整合酶基因下調(diào)最大。提示苦參堿能夠降低Ⅰ類整合子傳遞耐藥基因的效率,能夠起到阻止耐藥基因的傳播和細菌耐藥性的形成,具體機制仍需進一步深層次研究。
[Abstract]:Staphylococcus aureus, Streptococcus aureus and Escherichia coli are the main pathogens causing mastitis in dairy cows. Staphylococcus epidermidis (Staphylococcus epidermidis,Se) is considered to be a conditional pathogen with weak pathogenicity. With the development of research, it was found that Staphylococcus epidermidis is easy to form biofilm in cow breast environment, and the biofilm formed is the reserve of staphylococcus aureus resistant strains. These biological characteristics lead to an increase in bacterial resistance and multidrug resistance. Studies have shown that the bacterial integration subsystem plays an important role in the formation of bacterial resistance, and it can directly capture the genes of external drug resistance mediated by integrase. The expression of drug resistance gene box resulted in the formation of multidrug resistance of bacteria. In view of the important role of integron in the formation of bacterial drug resistance, it is of great theoretical and practical value to study the relationship between integron and drug resistance, as well as the action characteristics of drugs. In this study, drug resistance and integron distribution of Se in clinical mastitis were analyzed by pharmacology and molecular biology, and the relationship between integron and Se resistance was discussed. It was found that the resistance rate of clinically isolated Se to commonly used antimicrobial agents was 16.7- 100, with a wide spectrum of resistance and multidrug resistance, and the highest resistance rate of all isolates to penicillin was observed, and the epidemiological characteristics of bacterial integron were studied. The detectable rate of class 鈪，

本文編號：2277705