Novel ST3871exhibits diverse transmission modes, carrying the(X4) resistance gene.

Abstract

Although tigecycline is strictly restricted for use in animals, plasmid-mediated(X) is increasingly being detected in swine and poultry production, which may be associated with the highly intensive farming model and the use of antibiotics as feed additives., as one of the important reservoirs of(X), has attracted worldwide attention due to the complex plasmid background and the diversified mobile genetic elements (MGEs). This study isolated nine(X)-positivebelonging to a novel sequence type (ST), ST3871, from a commercial swine farm in Hebei, China. Phylogenetic analysis and pulsed-field gel electrophoresis (PFGE) demonstrated that clonal transmission drove the farm-level prevalence of these strains. The ST3871(X)-positiveexhibited resistance to multiple antibiotics and carried various resistance genes. Whole-genome sequencing (WGS) and southern blotting confirmed that these strains carried the plasmid-mediated(X4) gene. Conjugation assays revealed that(X4)-positive plasmids could be transferred intoand. Although the limited sampling range of this study limits further epidemic analysis, the emergence of(X)-mediated tigecycline resistance in a novel ST ofundeniably confirms that the(X) gene has resided in a wide variety of ST clones, highlighting the significant contribution ofto the dissemination of(X).IMPORTANCEcarrying(X) has spread globally, with the most extensive distribution observed in Asia. This study revealed the prevalence of a novel ST3871carrying the plasmid-mediated(X4) gene on a commercial swine farm in Hebei, China, indicating that the(X) gene, particularly plasmid-mediated(X), has been distributed across a wide variety ofST clones. This undoubtedly poses a threat to public health, necessitating comprehensive strategies and continuous monitoring to control it.