感染性心内膜炎链球菌耐药基因检测与分析  

Study of drug resistance genes of Streptococcus spp.causing infective endocarditis

作　　者：雷力成[1] 杨诺[1] 王佐岩[1] 杨水祥[1] 

机构地区：[1]首都医科大学附属北京世纪坛医院,北京100038

出　　处：《中国病原生物学杂志》2014年第6期564-567,共4页Journal of Pathogen Biology

摘　　要：目的通过分析感染性心内膜炎链球菌的耐药基因,以便有效控制链球菌耐药性的进一步发展,从而为感染性心内膜炎的治疗提供依据。方法从感染性心内膜炎患者血培养标本中分离链球菌,提取DNA,采用PCR方法检测耐药基因,并作测序分析。结果 PCR检测链球菌9种耐药基因,其中gyrA、parC、tetM基因扩增均阳性,且同源性较高。所有菌株的tetM基因同源性均为100%。有3株发生突变,突变位点分别为81位、87位和79位,且突变株均对氟喹诺酮类抗菌药物耐药。链球菌耐药基因编码氨基酸序列比对图显示,gyrA第81位由丝氨酸(Ser)突变为精氨酸(Arg),parC第87位由精氨酸(Arg)变异为亮氨酸(Leu),parC第79位由丝氨酸(Ser)突变为苯丙氨酸(Phe),因而可能导致耐药性的产生。结论分离自感染性心内膜炎患者的链球菌含有gyrA、parC、tetM基因,这3种基因可能与链球菌的耐药性有关。Objective To more effectively control the drug resistance of Streptococcus spp. by analyzing the drug resistance genes of Streptococcus spp. causing infective endocarditis in order to provide a basis for the treatment of infective endocarditis. Methods Streptococcus spp. were isolated from cultured blood samples of patients with infective endocarditis. DNA was extracted. The species were tested for drug resistance genes using PCR and sequenced. Results Nine drug resistance genes were identified by PCR. Isolates had evidence of amplification of the gyrA gene, parC gene, and tetM gene and the genes of different isolates were similar. Similarity of the tetM was 100% for the isolates. Three strains had mutations, which were located at codons 81, 87, and 79. These mutated strains were resistant to fluoroquinolone antimicrobials. Graphic depiction of the amino acid sequence of drug resistance genes of Streptococcus spp. indicated that codon 81 of the gyrA gene had mutated from serine （Ser） to arginine （Arg）, that codon 87 of the parC gene had mutated from arginine （Arg） to leucine （Leu）, and that codon 79 of the parC gene had mutated from serine （Ser） to phenylalanine （Phe）. These mutations had potentially led to drug resistance. Conclusion The Streptococcus spp. isolated from patients with infective endocarditis had the gyrA gene, the parC gene, and the tetM gene. These 3 genes may be associated with the drug resistance of Streptococcus spp.

关 键 词：感染性心内膜炎 链球菌 耐药基因 聚合酶链式反应 

分 类 号：R378.12[医药卫生—病原生物学]