内蒙古包头地区临床来源肠球菌耐药基因与致病基因的研究

发布时间：2018-03-11 14:14

本文选题：肠球菌　切入点：耐药机制　出处：《内蒙古科技大学包头医学院》2015年硕士论文　论文类型：学位论文

【摘要】：目的检测肠球菌在内蒙古包头地区的临床标本中及临床各科室中的分布特点和耐药性,了解肠球菌流行病学特征,为合理使用抗菌药物和防止耐药株的流行提供依据。研究包头地区耐药肠球菌致病基因及耐药基因的分布特点,探讨肠球菌耐药机制。方法应用琼脂筛选法检测117株临床来源的肠球菌菌株并分析其耐药性,从中选出50株,采用PCR法检测其6种致病基因cylA、gelE、esp、ace、agg、efaA,探讨其分布情况。采用PCR法检测肠球菌对氨基糖苷类、大环内脂类、糖肽类、四环素类抗生素耐药基因aac(6')-Ie-aph(2'')-Ia、aph(2'')-Ib、aph(2'')-Ic、aph(2'')-Id、aph(3')-IIIa、ant(6')-Ia、erm(B)、MazEF、vanA、vanB、tet(L),并分析其分布特点。检测β-内酰胺类、喹诺酮类抗生素的耐药基因PBP5,gyrA,parC,其扩增产物行DNA测序,分析突变区域,探讨基因突变与细菌耐药的相关性。结果(1)耐药性分析:实验菌株对9种抗菌药物均有不同程度的耐药,有半数以上的菌株对3种甚至3种以上抗生素耐药,屎肠球菌的耐药率高于粪肠球菌。(2)致病基因分布:肠球菌的致病基因检出率为:cylA(18%)、gelE(28%)、esp(16%)、ace(2%)、agg(0)、efaA在粪肠球菌中的检出率为92.9%。(3)耐药基因分布:实验菌株中HLGR的AME基因的携带率:aac(6')-Ie-aph(2'')-Ia(89.3%)、aph(2'')-Ib(0)、aph(2'')-Ic(7%)、aph(2'')-Id(10.7%)、aph(3')-IIIa(23.3%),HLSR的AME基因的携带率:aph(3')-IIIa(53.3%)、ant(6')-Ia(66.7%)。红霉素耐药基因ermB的携带率为83.3%。四环素的耐药基因tet(L)的携带率为73.91%。实验菌株对万古霉素耐药率为4.27%,VRE中仅有1株MazEF阳性,vanA、vanB均为阴性。(4)耐药基因突变分析:实验菌株中E.faecium的耐药基因PBP5携带率为100%,实验发现屎肠球菌的PBP5的C端两个新的氨基酸突变。氟喹诺酮类抗生素的耐药基因parC、gyrA携带率分别为87.5%、91.30%,实验发现parC、gyrA发生突变。结论(1)包头地区肠球菌对于9种临床应用的抗菌药物具有不同程度的耐药,并存在多重耐药菌株,而且不同类型肠球菌耐药谱不同。(2)肠球菌致病基因及耐药基因与肠球菌的抗生素耐药性具有明显的相关性。(3)通过对β-内酰胺类及喹诺酮类抗生素耐药基因PBP5、gyrA、parC突变分析,发现了屎肠球菌的PBP5的C末端两个新氨基酸突变,影响了与青霉素结合能力,并与细菌的耐药性相关。gyrA的突变位点为Ser83→Tyr、Ile、Arg,parC的突变位点为Ser80→Arg、Ile和Glu84→Ala。突变位点从亲水性氨基酸突变为疏水性氨基酸,使该位点亲水性降低,导致细菌耐药的产生。
[Abstract]:Objective to detect the distribution and drug resistance of Enterococcus in clinical specimens and clinical departments in Baotou, Inner Mongolia, and to understand the epidemiological characteristics of Enterococcus. To provide basis for rational use of antimicrobial agents and to prevent the epidemic of drug-resistant strains, the distribution characteristics of pathogenic genes and drug-resistant genes of drug-resistant Enterococcus in Baotou area were studied. Methods 117 clinical strains of Enterococcus were detected by Agar screening method and their drug resistance was analyzed. PCR method was used to detect six pathogenic genes, cylAgel EespaceaggefaA, and to investigate its distribution. PCR method was used to detect enterococcus to aminoglycosides, macrolipids, glycopeptides, tetracycline antibiotic resistant genes aacan6- Ie-aph-2a-Iaapaphora, and to analyze the distribution characteristics of 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamide, 尾 -lactamides, Quinolone antibiotic resistant gene PBP5gyrAparC.The amplified product was sequenced by DNA, the mutation region was analyzed, and the correlation between gene mutation and bacterial resistance was discussed. Results: the experimental strains were resistant to 9 antimicrobial agents to varying degrees. More than half of the strains were resistant to three or more antibiotics. The rate of drug resistance of Enterococcus faecium is higher than that of Enterococcus faecalis.) the distribution of pathogenic genes of Enterococcus faecium is higher than that of Enterococcus faecalis.) the detection rate of E. faecium is higher than that of Enterococcus faecalis. The detection rate of E. faecium is higher than that of Enterococcus faecalis. The detection rate of the pathogenic gene of Enterococcus faecium is higher than that of Enterococcus faecium. The detection rate of E. faecium is cylA1Af1818. The detection rate of E. faecii is cylAp1818. The detection rate of E. faecium is 92. 9%. 3) in Enterococcus faecium, the distribution of AME gene in E. faecalis is 92.9. 3): the carrying rate of the AME gene of HLGR in the experimental strain is aacap6- Iaaph-2a89.3. The carrying rate of AME gene was 53.3%. The carrying rate of erythromycin resistance gene (ermB) was 83.3%. The rate of tetracycline resistance gene was 73.91%. The rate of vancomycin resistance of experimental strains was 4.27%. Only 1 MazEF positive van AvanB gene was negative. Mutation analysis: the PBP5 carrying rate of E. faecium resistance gene was 100. Two new amino acid mutations at C-terminal of PBP5 of Enterococcus faecium were found. The carrying rate of fluoroquinolone antibiotic resistance gene parc gyrA was 87.5% and 91.30%, respectively. Conclusion Enterococcus in Baotou area is resistant to 9 kinds of antimicrobial agents. And there are multidrug resistant strains, Moreover, different types of enterococci have different drug resistance profiles.) Enterococcus pathogenicity genes and drug resistance genes have a significant correlation with antibiotic resistance of Enterococcus. The mutation analysis of 尾 -lactam and quinolone antibiotic resistance gene PBP5gyrAparC was carried out. Two new amino acid mutations at the C-terminal of PBP5 of Enterococcus faecium were found, which affected the binding ability to penicillin, and the mutation site related to bacterial resistance was Ser83. 鈫扵he mutation site of Tyrus Ileus Argoper C is Ser80. 鈫扐rg Ile and Glu84. 鈫扵he mutation site of Ala. changed from hydrophilic amino acid to hydrophobic amino acid, which reduced the hydrophilicity of Ala. and led to the production of drug resistance of bacteria.
【学位授予单位】：内蒙古科技大学包头医学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R440

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