ObjectivesTigecycline is recognized as one of the last-line antibiotics to treat serious bacterial infection caused by carbapenem-resistantKlebsiella pneumoniae(CRKP). The plasmid-borne genetet(X4) mediates high resistance to tigecycline. However, the prevalence and genetic context oftet(X4) inK. pneumoniaefrom various sources are not fully understood. Here, we investigated the prevalence oftet(X4)-positiveK. pneumoniaeand characterized the genetic context oftet(X4)-bearing plasmids inK. pneumoniaeisolates.MethodsPolymerase chain reaction (PCR) was used to detect thetet(X4) gene. The transferability of thetet(X4)-carrying plasmids was tested by conjugation assays. TheGalleria mellonellainfection model was used to test virulence oftet(X4)-positive strains. Whole-genome sequencing and genome-wide analysis were performed to identify the antimicrobial resistance and the virulence genes, and to clarify the genetic characteristics of thetet(X4)-positive isolates.ResultsAmong 921 samples, we identified twotet(X4)-positiveK. pneumoniaestrains collected from nasal swabs of two pigs (0.22%, 2/921). The twotet(X4)-positive isolates exhibited high minimum inhibitory concentrations to tigecycline (32–256 mg/L) and tetracycline (256 mg/L). The plasmids carrying thetet(X4) gene can transfer from the donor strainK. pneumoniaeto the recipient strainEscherichia coliJ53. Genetic analysis of the complete sequence of twotet(X4)-carrying plasmids pTKPN_3-186k-tetX4 and pTKPN_8-216k-tetX4 disclosed that thetet(X4) gene was flanked by delta ISCR2and IS1R, which may mediate the transmission of thetet(X4) gene.ConclusionThe prevalence oftet(X4)-positiveK. pneumoniaeamong different sources was low. ISCR2and IS1Rmay contribute to the horizontal transfer oftet(X4) gene. Effective measures should be taken to prevent the transmission oftet(X4)-producingK. pneumoniaein humans or animals.