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Abstract：
BACKGROUND: Urinary Tract Infection (UTI) is one of the most common bacterial infectious diseases which causes considerable morbidity and costly health problems. Uropathogenic Escherichia coli (UPEC), the most common pathogen causing UTI, is a highly heterogeneous group of extraintestinal pathogenic E. coli (ExPEC) which may carry a variety of virulence factors and belonging to different phylogenetic backgrounds. The current study aimed to investigate the frequency and association between various virulence factors (VFs) and phylogenetic groups of UPEC and commensal isolates.
METHODS: UPEC and commensal E. coli strains isolated from UTI and feces of healthy humans were compared for the presence of VFs and phylogenetic groups. Association between virulence genes was investigated and cluster analysis was employed.
RESULTS: According to the results, among a 30 virulence markers tested, the pathogenicity-associated island (PAI), papAH, papEF, fimH, fyuA, and traT genes prevalence were statistically significant in UPEC isolates. A strong association was found between the B2 and D phylogenetic groups and clinical isolates of UPEC; while, commensal isolates were mostly associated with phylogenetic group A. The aggregated VFs scores were more than twice higher in the UPEC isolates in comparison with the commensal isolates. Interestingly, the B2 group in both UPEC and commensal isolates had the highest VF scores. A strong positive association was found between several virulence genes. The clustering results demonstrated that UPEC or commensal E. coli isolates were highly heterogeneous due to different composition of their virulence gene pool and pathogenicity islands.
CONCLUSIONS: Genetic structure and VFs of UPEC strains vary from region to region; therefore, to control the UTI, the epidemiological aspects and characterization of the UPEC isolates need to be investigated in different regions. Since UPEC isolates are generally originate from the commensal strains, it may be feasible to reduce the UTI burden by interfering the intestinal colonization, particularly in the highly pathogenic clonal lineages such as B2.
METHODS: UPEC and commensal E. coli strains isolated from UTI and feces of healthy humans were compared for the presence of VFs and phylogenetic groups. Association between virulence genes was investigated and cluster analysis was employed.
RESULTS: According to the results, among a 30 virulence markers tested, the pathogenicity-associated island (PAI), papAH, papEF, fimH, fyuA, and traT genes prevalence were statistically significant in UPEC isolates. A strong association was found between the B2 and D phylogenetic groups and clinical isolates of UPEC; while, commensal isolates were mostly associated with phylogenetic group A. The aggregated VFs scores were more than twice higher in the UPEC isolates in comparison with the commensal isolates. Interestingly, the B2 group in both UPEC and commensal isolates had the highest VF scores. A strong positive association was found between several virulence genes. The clustering results demonstrated that UPEC or commensal E. coli isolates were highly heterogeneous due to different composition of their virulence gene pool and pathogenicity islands.
CONCLUSIONS: Genetic structure and VFs of UPEC strains vary from region to region; therefore, to control the UTI, the epidemiological aspects and characterization of the UPEC isolates need to be investigated in different regions. Since UPEC isolates are generally originate from the commensal strains, it may be feasible to reduce the UTI burden by interfering the intestinal colonization, particularly in the highly pathogenic clonal lineages such as B2.
摘要：
背景：尿路感染（UTI）是最常见的细菌感染性疾病之一，可导致相当大的发病率和昂贵的健康问题。尿路致病性大肠杆菌（UPEC），引起UTI的最常见病原体，是一组高度异质性的肠外致病性大肠杆菌（ExPEC），可能携带多种毒力因子，属于不同的系统发育背景。本研究旨在调查各种毒力因子（VFs）与UPEC和共生分离株的系统发育群体之间的频率和关联。
方法：比较了从健康人类UTI和粪便中分离的UPEC和共生大肠杆菌菌株的VF和系统发育群的存在。研究了毒力基因之间的关联，并采用聚类分析。
结果：根据结果，在测试的30个毒力标记中，致病性相关岛（PAI），爸爸,papEF,FIMH,fyuA,和traT基因患病率在UPEC分离株中具有统计学意义。在B2和D系统发育组和UPEC的临床分离株之间发现了很强的关联；而，共生分离株主要与系统发育组A相关。与共生分离株相比，UPEC分离株的总VFs得分高出两倍以上。有趣的是,在UPEC和共生分离株中,B2组的VF评分最高.在几个毒力基因之间发现了很强的正相关。聚类结果表明，由于其毒力基因库和致病性岛的组成不同，UPEC或共生大肠杆菌分离株具有高度异质性。
结论：UPEC菌株的遗传结构和VFs因地区而异；因此，为了控制UTI,需要在不同地区调查UPEC分离株的流行病学方面和特征。由于UPEC分离株通常来自共生菌株，通过干扰肠道定植来减少UTI负担可能是可行的，特别是在高致病性克隆谱系如B2中。
方法：比较了从健康人类UTI和粪便中分离的UPEC和共生大肠杆菌菌株的VF和系统发育群的存在。研究了毒力基因之间的关联，并采用聚类分析。
结果：根据结果，在测试的30个毒力标记中，致病性相关岛（PAI），爸爸,papEF,FIMH,fyuA,和traT基因患病率在UPEC分离株中具有统计学意义。在B2和D系统发育组和UPEC的临床分离株之间发现了很强的关联；而，共生分离株主要与系统发育组A相关。与共生分离株相比，UPEC分离株的总VFs得分高出两倍以上。有趣的是,在UPEC和共生分离株中,B2组的VF评分最高.在几个毒力基因之间发现了很强的正相关。聚类结果表明，由于其毒力基因库和致病性岛的组成不同，UPEC或共生大肠杆菌分离株具有高度异质性。
结论：UPEC菌株的遗传结构和VFs因地区而异；因此，为了控制UTI,需要在不同地区调查UPEC分离株的流行病学方面和特征。由于UPEC分离株通常来自共生菌株，通过干扰肠道定植来减少UTI负担可能是可行的，特别是在高致病性克隆谱系如B2中。
