尿路致病性大肠杆菌(UPEC)菌株引起大多数简单的尿路感染(UTI)。这些菌株是感染肠外部位的肠外致病性大肠杆菌(ExPEC)菌株的亚组,包括泌尿道,脑膜,血流,肺,和手术部位。这里,我们假设UPEC分离株比其他大肠杆菌分离株适应并在泌尿道内生长更快,并在该小生境中存活.迄今为止,没有可靠的方法来测量它们在体内的生长速率。在这里,我们使用了两种方法:非复制质粒pGTR902的分离和峰谷比(PTR),一种基于测序的方法,用于计算细胞分裂过程中存在的细菌染色体复制叉。在UTI的鼠模型中,UPEC菌株在体内生长强劲,匹配或超过体外生长速率,并且仅在接种后24和30小时(hpi)达到高CFU计数后才减慢。相比之下,无症状菌尿(ABU)菌株倾向于在6、24和30hpi保持体内高生长速率,人口密度没有增加,表明宿主反应或消除限制了人口增长。粪便菌株在6hpi时显示出中等的生长速率,但无法存活到以后。由PTR,人类尿路感染患者尿中的大肠杆菌在活动性感染期间表现出非常迅速的生长,平均倍增时间为22.4分钟。因此,除了传统的毒力决定因素,包括粘附素,毒素,铁收购,和运动性,非常高的体内生长速率和对先天免疫应答的抗性似乎是UPEC菌株的关键表型。重要性尿致病性大肠杆菌(UPEC)菌株在其他健康女性中引起大多数尿路感染。虽然我们了解大肠杆菌利用许多毒力因子在泌尿道内定植并持续存在,除非细菌能够迅速分裂并在宿主免疫反应中存活,否则这些特性是无关紧要的。为了确定增长率对成功的殖民和持久性的贡献,我们采用了两种方法:一种涉及在细菌分裂时分离非复制质粒和峰谷比,一种基于测序的方法,用于计算细胞分裂过程中存在的染色体复制叉。我们发现UPEC菌株在人类UTI期间分裂异常迅速。这些技术将广泛适用于在宿主定殖期间测量其他细菌病原体的体内生长速率。
Uropathogenic Escherichia coli (UPEC) strains cause most uncomplicated urinary tract infections (UTIs). These strains are a subgroup of extraintestinal pathogenic E. coli (ExPEC) strains that infect extraintestinal sites, including urinary tract, meninges, bloodstream, lungs, and surgical sites. Here, we hypothesize that UPEC isolates adapt to and grow more rapidly within the urinary tract than other E. coli isolates and survive in that niche. To date, there has not been a reliable method available to measure their growth rate in vivo Here we used two methods: segregation of nonreplicating plasmid pGTR902, and peak-to-trough ratio (PTR), a sequencing-based method that enumerates bacterial chromosomal replication forks present during cell division. In the murine model of UTI, UPEC strain growth was robust in vivo, matching or exceeding in vitro growth rates and only slowing after reaching high CFU counts at 24 and 30 h postinoculation (hpi). In contrast, asymptomatic bacteriuria (
ABU) strains tended to maintain high growth rates in vivo at 6, 24, and 30 hpi, and population densities did not increase, suggesting that host responses or elimination limited population growth. Fecal strains displayed moderate growth rates at 6 hpi but did not survive to later times. By PTR, E. coli in urine of human patients with UTIs displayed extraordinarily rapid growth during active infection, with a mean doubling time of 22.4 min. Thus, in addition to traditional virulence determinants, including adhesins, toxins, iron acquisition, and motility, very high growth rates in vivo and resistance to the innate immune response appear to be critical phenotypes of UPEC strains.IMPORTANCE Uropathogenic Escherichia coli (UPEC) strains cause most urinary tract infections in otherwise healthy women. While we understand numerous virulence factors are utilized by E. coli to colonize and persist within the urinary tract, these properties are inconsequential unless bacteria can divide rapidly and survive the host immune response. To determine the contribution of growth rate to successful colonization and persistence, we employed two methods: one involving the segregation of a nonreplicating plasmid in bacteria as they divide and the peak-to-trough ratio, a sequencing-based method that enumerates chromosomal replication forks present during cell division. We found that UPEC strains divide extraordinarily rapidly during human UTIs. These techniques will be broadly applicable to measure in vivo growth rates of other bacterial pathogens during host colonization.