IS-flanked composite transposon harboring in multidrug-resistant Typhimurium.

Multidrug-resistant Typhimurium has emerged as a global public health concern. Asymptomatic gastrointestinal carriage is a key factor in the spread of antibiotic-resistant bacteria. However, it is challenging to obtain direct evidence of transfer of mobile genetic elements (MGEs). Here, we found that MGEs harboring were transferred from asymptomatic (LS20223694) to Typhimurium (LS20223695) in a child. BLAST analyses demonstrated that the IS-flanked composite transposon of pLS20223695_NDM5 showed high similarity with pLS20223694_NDM5 and two previously reported plasmids, suggesting the possibility of genetic recombination. Besides, conjugation experiments showed that the transconjugant carried the incompatibility group I1 (IncI1)-I(alpha) plasmid replicon with the and genes, indicating that pLS20223695_NDM5 is a conjugative plasmid with transferability. Our study provides insights into the genetic basis of an IS-flanked composite transposon in Typhimurium.