反复性泌尿系感染大肠埃希菌的毒力因子分布及耐药性研究

Distribution of virulence factors and drug resistance characteristics of Escherichia coli causing recurrent urinary tract infections

目的研究反复性泌尿系感染大肠埃希菌的毒力因子分布及耐药性特征,为大肠埃希菌所致的反复性泌尿系感染的临床诊断和治疗提供依据。方法收集2007-2011年大肠埃希菌所致反复性泌尿系感染病例,通过PFGE分型确定导致反复性泌尿系感染的大肠埃希菌是否为同一株菌株,并据此分为持续感染组(同一株菌株39株)以及再感染初次分离组、再次分离组(不同菌株各35株),多重PCR方法测定大肠埃希菌的系统发生分型及黏附因子、铁载体相关因子、毒素及保护性物质等毒力基因的分布,K-B法测定大肠埃希菌的药物敏感性,应用CHISS软件进行统计分析。结果持续感染组系统发生分型以B2型为主,黏附因子pap G和iha、铁载体相关因子fyu A、irp-2和iut A,阳性率分别为51.28%、48.72%、84.61%、87.18%、87.18%,明显高于再感染初次分离组的28.57%、31.43%、51.43%、60.00%、57.14%和再次分离组的34.29%、28.57%、65.71%、71.43%、60.00%,差异有统计学意义(P<0.05);持续感染组大肠埃希菌具有的毒力基因种类数(6.6±1.9)种明显高于再感染初次分离组(5.3±2.3)种和再次分离组(5.6±2.2)种,差异有统计学意义(P<0.05);除阿米卡星、头孢他啶和亚胺培南外,3组大肠埃希菌对环丙沙星、磺胺甲噁唑/甲氧苄啶、哌拉西林耐药率均较高。结论反复性泌尿系感染可能存在胞内感染机制,大肠埃希菌高度的耐药性需引起临床高度关注。

OBJECTIVE To study the distribution of virulence factors and drug resistance characteristics of Esche- richia coli isolated from recurrent urinary tract infections, in order to provide basis for clinical diagnosis and treatment of recurrent urinary tract infections caused by E. coli. METHODS PFGE was used to determine whether recurrent urinary infections were caused by the same strain or not and E. coli isolates were classified into persistence group （39 strains） and re-infection first isolated group and second isolated group （35 strains each）. The distribution of E. coli phylogenetic classification and virulence factors, such as adhesion factor, siderophores, toxins, were determined by multiple PCR method. Drug sensitivity was tested by K-B method. RESULTS Strains of persistence group most belongs to phylogenetic group B2, and adhesion factors （pap G and iha） and siderophores （fyuA, irp-2 and iutA） of persistence group （51. 28%,48. 72%,84. 61%,87. 18%,87. 18%, respectively） were significantly higher than those of re-infection first isolated group （28.57% ,31.43 % ,51.43%, 60.00% ,57. 14%, respectively） and second isolated group （34. 29%,28. 57%, 65. 71%, 71. 43%, 60. 00%, respectively）, with statistical significance （P〈0.05）. The number of virulence factors of persistence group （6.6 ±1.9） was significantly higher than that of re-infection first isolated group （5.3±2.3） and second isolated group （5.6±2.2）, with statistical significance（P〈0. 05）. Except amikacin, ceftazidime and imipenem, E. coli had high resistant rates to other measured drugs such as ciprofloxacin, trimethoprim-sulfamethoxazole, andpiperacillin. CONCLUSION There is a potential intracellular infection mechanism in recurrent urinary tract infection. It is important to pay attention to serious multiple antibiotic resistance of E. coli from urinary tract infections.