Microbiology Institute, Universidad San Francisco de Quito, Ecuador.
Environmental Health Sciences Division, University of California, Berkeley, California.
J Glob Antimicrob Resist. 2022 Jun;29:136-140. doi: 10.1016/j.jgar.2022.03.002. Epub 2022 Mar 10.
The gastrointestinal tract constitutes a complex and diverse ecosystem. Escherichia coli is one of the most frequently studied and characterised species in the gut ecosystem; nevertheless, there has been little research to determine their diversity and population dynamics in the intestines of children over time. We analysed the turnover or dominant E. coli isolates in children faecal matter during 1 year.
In this prospective study, a fresh faecal sample was obtained from children longitudinally over one year (30 faecal samples at sampling period 1 and 22 faecal samples at sampling periods 2 and 3). From each stool sample, five E. coli colonies were randomly selected (n = 405 E. coli isolates total) in order to characterize the genotype and phenotypic antimicrobial resistance patterns.
We were unable to find same E. coli dominant clone in faecal matter from 30 children in different sampling periods. Whole-genome sequencing of three isolates belonging to ST131 found in one child during the sampling period I and II indicated that isolates were three different ST 131 clones that carried extended-spectrum β-lactamase (ESBL) genes.
We found that all numerically dominant E. coli lineages in children's intestines were transient colonisers, and antimicrobial resistance phenotypes of these strains varied significantly over time without any apparent selective force.
胃肠道构成了一个复杂多样的生态系统。大肠杆菌是肠道生态系统中研究和描述最多的物种之一；然而，对于其在儿童肠道中的多样性和种群动态，研究甚少。我们分析了在 1 年内儿童粪便中优势大肠杆菌分离株的更替情况。
在这项前瞻性研究中，对儿童的粪便样本进行了为期一年的纵向采集（第 1 采样期采集 30 份粪便样本，第 2 和第 3 采样期各采集 22 份粪便样本）。为了确定基因型和表型抗菌药物耐药模式，从每个粪便样本中随机选择 5 个大肠杆菌菌落（共 405 个大肠杆菌分离株）。
我们无法在不同采样期的 30 个儿童的粪便中找到相同的优势大肠杆菌克隆。对在第 1 和第 2 采样期在一名儿童粪便中发现的 3 株属于 ST131 的分离株进行全基因组测序表明，这些分离株是携带超广谱β-内酰胺酶（ESBL）基因的三个不同的 ST131 克隆。
我们发现儿童肠道中所有数量上的优势大肠杆菌谱系均为一过性定植者，这些菌株的抗菌药物耐药表型随时间变化显著，而没有明显的选择压力。
