新型抗菌增敏剂通过调控自溶系统逆转MRSA对β-内酰胺类耐药性的分子机制研究

Meticillin-resistant Staphylococcus aureus (MRSA) is one of the principal multiply resistant pathogenic bacteria that causes serious healthcare-associated and community-onset infections, and is resistant to all kinds of antibiotics especially of beta-lactams. The resistance mechanism of MRSA to β-lactam antibiotics involves the penicillin-binding protein-PBP2a and stable autolysis system in order to maintain the synthesis of cell wall. Previously, we succeeded to isolate catechin compounds CE from hawthorn depending on the antibacterial sensitizating activity. CE showed obvious antibacterial sensitizating activity in vitro and in vivo. There is no connection between the mechanism of this activity and β-lactamase and PBP2a, but it may affect bacteria autolysis enzyme system and decrease sarA gene mRNA expression. To examine the mechanism of the CE`s antibacterial sensitizating activity, we plan our research as follows: ①study the influence of CE to sarA and genes in its regulatory systems in order to identify and screen which is the most ovbious change. ②Knocking down sarA mRNA expression with antisense oligonucleotide technology, study the influence of CE on Antibacterial sensitization activity and the change of autolysis systems. ③ Knocking down the gene mRNA expression with antisense oligonucleotide technology which is selected from the first step, study the influence of CE on Antibacterial sensitization activity and the change of autolysis systems again. In order to identify the mechanism and target of CE.

耐甲氧西林金黄色葡萄球菌（MRSA）是院内外感染的重要病原菌，呈多重耐药。对β-内酰胺类的特殊耐药机制为表达耐药蛋白PBP2a和稳定的自溶酶系统以继续维持细胞壁的合成。本项目前期以抗菌增敏活性为导向，从山楂中分离到儿茶素类化合物CE，CE共同作用具有显著的体内、外抗菌增敏活性。其作用机制与β-内酰胺酶和PBP2a无关，与影响细菌自溶酶系统的基因sarA有关。本项目以标准株WHO-2为研究对象，首先研究CE对sarA及其调控网络中各基因的影响，明确及筛选变化最明显的基因；其次封闭sarA，研究CE的抗菌增敏作用及自溶酶系统功能学的变化；再次，封闭sarA调控网络中变化最明显的基因，再次观察CE的抗菌增敏作用及自溶酶系统功能学的变化，从而明确CE的抗菌增敏作用机制和作用靶点，为MRSA抗菌增敏剂的研发提供新的靶点及研究思路。