Prevalence and Plasmid Characterization of the qnrD Determinant in Enterobacteriaceae Isolated from Animals, Retail Meat Products, and Humans

qnrD, unlike other qnr genes, is mainly located on small nonconjugative plasmids. We investigated the presence of qnrD among 1,373 Enterobacteriaceae isolates in China. Twelve qnrD-positive strains were detected, and all were nonsusceptible to fluoroquinolones. The complete sequence of plasmids showed that the qnrD determinants were located on two plasmids with a respective size of ∼4.2 and 2.7 k-bp. Interestingly, the identification of qnrD in this study revealed the highest prevalence of Proteeae among Enterobacteriaceae identified.