Tn6450, a Novel Multidrug Resistance Transposon Characterized in a Proteus mirabilis Isolate from Chicken in China

A novel 65.8-kb multidrug resistance transposon, designated Tn6450, was characterized in a Proteus mirabilis isolate from chicken in China. Tn6450 contains 18 different antimicrobial resistance genes, including cephalosporinase gene bla(DHA-1) and fluoroquinolone resistance genes qnrA1 and aac(6')-Ib-cr. It carries a class 1/2 hybrid integron composed of intI2 and a 3' conserved segment of the class 1 integron. Tn6450 is derived from Tn7 via acquisition of new mobile elements and resistance genes.