产ESBLs肠杆菌科细菌中整合子参与多重耐药机制研究

Integron-mediated multidrug resistance in clinial ESBLs-produing multiresistent strains of Enterobacteriacease

目的 观察产超广谱 β-内酰胺酶 (ESBL s)菌株的多重耐药情况 ,并分析产 ESBL s菌株中整合子的存在 ,同时对整合子的特性进行了初步研究。方法 采用 VITEK GNS药敏板测定庆大霉素等 13种抗菌药物对 12 6株产 ESBL s的肠杆菌属细菌的最低抑菌浓度 (MIC)。PCR技术检测整合子基因 ,应用 PCR定位技术和 DNA测序研究整合子插入耐药基因的情况。结果产 ESBL s的菌株对第三代头孢菌素、氨基糖苷、喹诺酮、磺胺类代表药如头孢噻肟、庆大霉素、培氟沙星、磺胺甲口恶唑 /甲氧苄氨嘧啶 (SMZ/ TMP)的耐药率分别为76 .2 %、6 7.5 %、76 .2 %、6 3.5 % ,对碳青霉烯类的亚胺培南全部敏感。产 ESBL s菌株质粒上存在三种大小不同的整合子 (扩增片段 94 0、180 0、2 6 0 0 bp) ,含有二氢叶酸还原酶基因和 β-内酰胺酶基因和核苷转移酶基因。结论 产 ESBL s菌株和非产 ESBL s菌株相比呈多重耐药 ,产 ESBL s菌株存在不同类型的整合子结构 ,含有多种耐药基因。整合子可以在细菌种内和种间引起多重耐药的水平传播。

Objective To study multidrug resistance of different antimicrobial agents in ESBLs producing strains of Enterobacteriaceae and to investigate the presence and characterization of multiresistance associated integron. Methods MICs of 13 different antimicrobial agents against 126 isolates of Enterobacteriaceae were determined by VITEK GNS card. Integron was determined by PCR with integron specific primer. PCR mapping and DNA sequencing were used to analyze resistant gene in integron. Results Resistant rate of ESBLs producing isolates to cefotaxime, gentamicin, pefloxacin and SMZ/TMP were 76.2%, 67.5%, 76.2% and 63 5% respectively. Imipenem showed good antimicrobial activity. Three different integron were detected in ESBLs producing strains, dhfrXII gene, β lactamase gene and nucleotidyltransferase gene were inserted into integron . Conclusinos ESBLs producing strains of Enterobacteriaceae revealed that multidrug resistence carrying integron multiresistant gene was expressed in clinial ESBLs producing isolates. Integron mediated horizontal resistant transference can be transferred either intra and/or interspecies.