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目的了解辽宁省大连市分离的耐亚胺培南铜绿假单胞菌(PA)的金属β-内酰胺酶携带情况,探讨该地区临床分离产金属β-内酰胺酶PA的染色体多态性特征。方法选取2013年1月至2014年9月临床分离的400株PA进行菌种鉴定和药物敏感试验,聚合酶链反应(PCR)法扩增产金属β-内酰胺酶的基因,并对扩增阳性产物进行测序确认;脉冲场凝胶电泳(PFGE)检测分析其染色体多态性。结果药敏结果发现有89株PA对亚胺培南耐药,且多数为多重耐药菌株;金属β-内酰胺酶基因PCR扩增阳性11株,其中8株检出IMP-1基因,3株检出VIM-2基因,其余几种金属β-内酰胺酶基因均未检出。89株耐亚胺培南PA的PFGE图谱可分成15种型(A~O),其中A型46株、B型16株、C型4株、D型5株、E型4株、F型3株、G型2株、H型2株,I型至O型分别各有1株。PFGE图谱集中的A~G型各型中的菌株来源于4家不同医院,呈现多态性,每群均存在型别100%相同的克隆株。结论大连地区耐亚胺培南的89株PA多数是多重耐药菌株,产金属β-内酰胺酶的基因型只有2种,为IMP-1和VIM-2。PFGE结果提示该地区菌株虽具有基因多态性,但仍存在相似度较高的流行优势PFGE型别,具有高度的同源性。PFGE具有很强的菌株同源性分析能力,适用于细菌耐药传染源溯源。
Objective To investigate the metal β-lactamase carrying in imipenem-resistant Pseudomonas aeruginosa (PA) isolated in Dalian, Liaoning Province, and to explore the characteristics of chromosome polymorphism of the metallo-β-lactamase PA isolated in this area . Methods 400 PA isolates clinically isolated from January 2013 to September 2014 were selected for bacterial identification and drug susceptibility testing. The gene encoding metallo-β-lactamase was amplified by polymerase chain reaction (PCR) Positive products were confirmed by sequencing; pulsed-field gel electrophoresis (PFGE) detection of chromosome polymorphism. Results There were 89 strains of PA resistant to imipenem and most of them were multidrug-resistant strains. 11 strains of metallo-β-lactamase gene were amplified by PCR, including 8 strains of IMP-1 and 3 VIM-2 gene was detected in the strains, and the other metal β-lactamase genes were not detected. The PFGE profiles of 89 imipenem - resistant PA strains were divided into 15 types (A ~ O), including 46 strains of type A, 16 of type B, 4 of type C, 5 of type D, 4 of type E, 3 strains, 2 strains of G type, 2 strains of H type and 1 strain of type I to 0 respectively. Strains of AGE genotypes in the PFGE atlas originated from 4 different hospitals and showed polymorphism, with 100% identical clones in each group. Conclusion Most of the 89 PA-resistant strains of imipenem in Dalian are multi-drug resistant strains. There are only 2 genotypes of metal-producing β-lactamase, which are IMP-1 and VIM-2. The results of PFGE suggested that although there are genetic polymorphisms in this region, there is still a high prevalence of PFGE genotypes with high homology. PFGE has strong ability of homology analysis of bacterial strains, and is suitable for tracing the source of bacterial resistance to infection.