ASB及UTI患者尿液中分离的大肠埃希菌系统分群、毒力基因及耐药性分析

Phylogenetic grouping,virulence genes and drug resistance of E.coli strains isolated from patients with asymptomatic bacteriuria and urinary tract infection

目的对无症状菌尿(ASB)及症状性尿路感染(UTI)患者尿液中分离的大肠埃希菌进行系统分群、毒力基因及耐药性检测。方法收集该院2014年5月至2016年3月从尿路感染患者尿液中分离的大肠埃希菌共145株,其中ASB组65株,UTI组80株。利用多重聚合酶链反应(PCR)对其进行系统分群及10种毒力基因表达检测;采用纸片扩散(K-B)法对其进行耐药性检测。结果ASB组中,A、B1、B2、D群分别占10.77%、38.47%、43.07%、7.69%。UTI组中,A、B1、B2、D群分别占12.50%、10.00%、62.50%、15.00%,两组系统分群结果差异有统计学意义(P<0.05)。ASB组黏附相关基因afa和sfa的表达率高于UTI组(P<0.05)。UTI组细胞毒性相关基因细胞毒性坏死因子1(cnf1)和溶血素(hlyA),铁摄取相关基因fyuA和iutA的表达率高于ASB组(P<0.05)。ASB组和UTI组对18种抗菌药物的耐药率及产超广谱β-内酰胺酶菌株阳性率差异无统计学意义(P>0.05)。结论 ASB和UTI不同的系统分群特征,可能与其表现出不同的致病能力有关。ASB菌株毒力较UTI低,降低了其急性致病能力,但具有更高表达率的黏附相关基因,这可能有助于细菌实现持续定植。尿路感染大肠埃希菌的高耐药率必须引起临床重视。

Objective To conduct the phylogenetic grouping,virulence genes and antimicrobial resistance detection of Escherichia coli （E.coli） strains isolated from the patients with asymptomatic bacteriuria （ASB） and symptomatic urinary tract infection （UTI）. Methods A total of 145 strains of E.Coli isolated from the urine of the patients with UTI were collected in this hospital from May 2014 to March 2016,including 65 strains in the ABS group and 80 strains in the UTI group.The phylogenetic grouping and 10 virulence gene expression detection were performed by using the multiplex polymerase chain reaction （PCR）.The drug resistance was detected by adopting the K-B method. Results The A,B1,B2 and D groups in the ASB group accounted for 10.77 %,38.47%,43.07% and 7.69% respectively.In the UTI group,the group A,B1,B2 and D accounted for 12.50%,10.00%,62.50% and 15.00% respectively.The difference in phylogenetic grouping results had statistical difference between the two groups （ P 〈0.05）.The expression rates of adhesion related genes afa and sfa in the ASB group were higher than those in the UTI group （ P 〈0.05）.The expression rates of cytotoxic related genes cnf1 and hlyA,and iron uptake related genes fyuA and iutA in the UTI group were higher than those in the ASB group （ P 〈0.05）.The resistance rates to 18 antibacterial drugs and positive rate of bacterial strains producing extended-spectrum β-lactamases had no statistical difference between the ASB group and UTI group （ P 〉0.05）. Conclusion The different phylogenetic grouping characteristics between the ASB and UTI may be related to their different pathogenic abilities.The virulence of E.Coli strains in the ASB is lower than that in the UTI,which may lower their acute pathogenic ability.But E.Coli strains in the ASB have adhesion related genes with higher expression rates,which can help the bacteria to realize the continuous colonization.The high drug resistance rates of UPEC must be paid attention to in clinic.