Community gut colonization by tet(X4)-positive multidrug-resistant Escherichia coli in healthy individuals from urban residents in Shenzhen, China

作者：Ruoyan Peng, Pei Liang, Wenxiao Jiang, Zhaodong Li, Lijun Wang, Yi‐Hsiang Huang, Xianfang Zhang, Yijia Guo, Yingying Wang, Jing Wang, Jiubiao Guo, Feifei Yin, Dachuan Lin · 发表于：Frontiers in Cellular and Infection Microbiology · 年份：2025 · DOI：10.3389/fcimb.2025.1667196 · 被引用次数：4 · 研究领域：Antibiotic Resistance in Bacteria、Gut microbiota and health、Escherichia coli research studies

Background Tigecycline remains a last-resort antibiotic for treating multidrug-resistant (MDR) Gram-negative pathogens. The emergence of tet (X4)-mediated high-level tigecycline resistance in Escherichia coli has raised global concern, yet its prevalence in healthy human populations remains limited. Methods We conducted a community-based surveillance study involving 245 fecal samples from healthy individuals in three urban communities in Shenzhen, China. Tigecycine-resistant strains were isolated using MacConkey agar supplemented with 2 mg/L tigecycline and confirmed by PCR detection of tet (X). Antimicrobial susceptibility testing, whole-genome sequencing (WGS), and phylogenetic analysis were performed. Results Tigecycline-resistant E. coli were detected in 1.6% (4/245) of samples. All isolates carried tet (X4) and exhibited an MDR phenotype. WGS revealed that tet (X4) was located on IncY (n=1) and IncFIA8-IncHI1/ST17 plasmids (n=3), which closely resembled previously described plasmids and co-harbored additional resistance genes. The core tet (X4)-carrying region in all four plasmids, associated with IS CR2 , was highly similar to that of p47EC—the first tet (X4)-bearing plasmid identified in porcine E. coli in China. Notably, the three IncFIA-IncHI1/ST17 plasmids shared an identical 12,536-bp region structured as IS 1 – catD – tet (X4)–IS CR2 –ΔIS CR2 – floR –ΔIS CR2. Virulence-associated genes involved in adhesion, iron acquisition, biofilm formation, and secretion system...