Microbiology and Immunology Department, UR02SP13, Farhat Hached Teaching Hospital, Av. Ibn el Jazzar, 4000, Sousse, Tunisia.
Int J Infect Dis. 2013 Jun;17(6):e450-3. doi: 10.1016/j.ijid.2013.01.025. Epub 2013 Mar 16.
Escherichia coli is the predominant pathogen causing urinary tract infection (UTI), the most common bacterial infectious disease encountered in clinical practice, accounting for significant morbidity and high medical costs. The severity of UTI produced by E. coli is due to the expression of a wide spectrum of virulence factors. In this study we evaluated the role of E. coli virulence determinants in the pathogenesis of UTI.
A total of 90 uropathogenic E. coli strains were screened by PCR for the prevalence of seven virulence genes encoding type 1 fimbriae (fimH), pili associated with pyelonephritis (pap), S and F1C fimbriae (sfa and foc), afimbrial adhesins (afa), cytotoxic necrotizing factor (cnf), hemolysin (hly), and aerobactin (aer).
The prevalence of genes coding for fimbrial adhesive systems was 68% for fimH, 41% for pap, and 34% for sfa/foc. The operons coding for afa afimbrial adhesins were identified in 20% of strains. The hly and cnf genes coding for toxins were amplified in 19% and 3% of strains, respectively. A prevalence of 52% was found for the aer gene. The various combinations of detected genes were designated as virulence patterns. The strains isolated from hospitalized patients displayed a great diversity of gene associations compared to those isolated from ambulatory patients.
Our study showed that investigation of the bacterial pathogenicity associated with UTI may contribute to a better medical intervention.
大肠埃希菌是引起尿路感染（UTI）的主要病原体，UTI 是临床实践中最常见的细菌性传染病，发病率高，医疗费用高。大肠埃希菌引起的 UTI 的严重程度是由于其表达广泛的毒力因子。在这项研究中，我们评估了大肠埃希菌毒力决定因素在 UTI 发病机制中的作用。
通过 PCR 筛选了 90 株尿路致病性大肠埃希菌，以检测编码 1 型菌毛（fimH）、与肾盂肾炎相关的菌毛（pap）、S 和 F1C 菌毛（sfa 和 foc）、无菌毛黏附素（afa）、细胞毒性坏死因子（cnf）、溶血素（hly）和铁载体（aer）的 7 种毒力基因的流行情况。
编码菌毛黏附系统的基因流行率为 fimH 为 68%，pap 为 41%，sfa/foc 为 34%。20%的菌株中鉴定出编码 afa 无菌毛黏附素的操纵子。编码毒素的 hly 和 cnf 基因在 19%和 3%的菌株中扩增。aer 基因的流行率为 52%。检测到的基因的各种组合被指定为毒力模式。与门诊患者分离的菌株相比，住院患者分离的菌株显示出基因关联的多样性。
我们的研究表明，对与 UTI 相关的细菌致病性的调查可能有助于更好的医疗干预。
