多重耐药基因cfr在食源性金黄色葡萄球菌中传播的分子机制研究

金黄色葡萄球菌是一种重要的食源性致病菌，在许多食品中均可检出。近年来，伴随着抗生素的大量使用，金葡菌的耐药问题日益突出。cfr是目前发现的唯一一种可同时介导对五种化学结构不同的抗菌药物（酰胺醇类、林可霉素类、截短侧耳素类、恶唑烷酮类和链阳菌素A类）耐药的多重耐药基因，也是迄今为止发现的第一种可介导利奈唑胺耐药的可转移耐药基因。目前，关于cfr基因在人源和动物源中的检出均有相关报道，但食品源中的现状并不清楚。因此，本项目将基于本课题组前期建立的全国食品源金黄色葡萄球菌菌种数据库，对相关菌株进行cfr基因的检测，并通过可转移性分析、全基因组及全质粒测序、生物信息学分析等阐明cfr基因在食源性金葡菌中的分子传播机制。本研究将有助于全面理解cfr基因在食品中的起源，为cfr基因的传播机制提供更多基础科学数据，同时也为食品源耐药菌/耐药基因扩散传播的风险评估和防控提供重要理论依据。

Staphylococcus aureus is an important foodborne pathogens, which was detected in many kinds of food. With the abuse of antibiotics, the resistance of pathogens was more and more serious in recent years. The cfr gene was found to be the resistance gene which can resist at least five chemically unrelated antimicrobial classes: phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A antibiotics. This gene is also found to mediates linezolid resistance by coding for Cfr methyltransferase that catalyzes enzymatic methylation of adenosine in position 2503 of the 23S rRNA. Nowadays, the detection of cfr in clinlic and animals source was reported in many previous studies, but the situation of food source were not clear. Therefore, it is significant to research the distribution and dissemination of cfr among foodborne Staphylococcus aureus. In our research we are going to study the prevalence of cfr in foodborne Staphylococcus aureus by PCR method. Then, PFGE will be used to study the phenotype of cfr positive bacteria. The molecular mechanism of transmission of cfr gene in foodborne Staphylococcus aureus will be characterized by southern blotting, conjugation and transformation experiments, genome sequencing, plasmid sequencing, and bioinformatics analysis. All these studies could elucidate the mechanism of transmission of cfr gene in foodborne Staphylococcus aureus, which will provide a theoretical basis for risk assessment and control of the transmission of foodborne resistant bacteria and resistant gene.