Travel to tropical regions is associated with high risk of acquiring extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) that are typically cleared in less than 3 months following return. The conditions leading to persistent carriage that exceeds 3 months in some travellers require investigation. Whole-genome sequencing (Illumina MiSeq) was performed on the 82 ESBL-E isolates detected upon return and 1, 2, 3, 6 and 12 months later from the stools of 11 long-term (>3 months) ESBL-E carriers following travel abroad. One to five different ESBL Escherichia coli strains were detected per traveller upon return, and this diminished to one after 3 months. Long-term carriage was due to the presence of the same ESBL E. coli strain, for more than 3 months, in 9 out of 11 travellers, belonging to epidemic sequence type complexes (STc 10, 14, 38, 69, 131 and 648). The mean carriage duration of strains belonging to phylogroups B2/D/F, associated with extra-intestinal virulence, was higher than that for commensal-associated A/B1/E phylogroups (3.5 vs 0.5 months, P=0.021). Genes encoding iron capture systems (fyuA, irp), toxins (senB, sat), adhesins (flu, daaF, afa/nfaE, pap, ecpA) and colicin (cjrA) were more often present in persistent strains than in transient ones. Single-nucleotide polymorphism (SNP) analysis in persistent strains showed a maximum divergence of eight SNPs over 12 months without signs of adaptation. Genomic plasticity was observed during the follow-up with the loss or gain of mobile genetic elements such as plasmids, integrons and/or transposons that may contain resistance genes at different points in the follow-up. Long-term colonization of ESBL-E following travel is primarily due to the acquisition of E. coli strains belonging to epidemic clones and harbouring ‘virulence genes’, allowing good adaptation to the intestinal microbiota.

中文翻译：

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出国旅行后长期携带者中产超广谱 β-内酰胺酶的肠杆菌的定植动态

前往热带地区旅行与获得产超广谱 β-内酰胺酶肠杆菌(ESBL-E) 的高风险相关，这些肠杆菌通常在返回后不到 3 个月内被清除。导致某些旅行者持续携带超过 3 个月的情况需要调查。对 11 名长期（>3 个月）ESBL-E 携带者返回后和 1、2、3、6 和 12 个月后检测到的 82 株 ESBL-E 分离株进行全基因组测序 (Illumina MiSeq)出国旅行。每位旅客返回后检测到1 到 5 种不同的 ESBL大肠杆菌菌株，3 个月后减少到 1 种。长期携带是由于存在相同的 ESBL大肠杆菌 11 名旅行者中有 9 名感染了 3 个月以上的菌株，属于流行序列型复合体（STc 10、14、38、69、131 和 648）。与肠外毒力相关的属于系统群 B2/D/F 的菌株的平均携带持续时间高于与共生相关的 A/B1/E 系统群的平均携带时间（3.5 个月 vs 0.5 个月，P = 0.021）。编码铁捕获系统（fyuA、irp）、毒素（senB、sat）、粘附素（flu、daaF、afa/nfaE、pap、ecpA）和大肠菌素（cjrA ）的基因) 在持久性菌株中比在短暂性菌株中更常见。持久性菌株中的单核苷酸多态性 (SNP) 分析显示，在 12 个月内，8 个 SNP 的最大分歧没有适应迹象。在随访期间观察到基因组可塑性，在随访的不同时间点可能含有抗性基因的可移动遗传元件（如质粒、整合子和/或转座子）的丢失或获得。旅行后 ESBL-E 的长期定植主要是由于获得了属于流行性克隆并具有“毒力基因”的大肠杆菌菌株，从而能够很好地适应肠道微生物群。