Novel quinolone resistance determinant, qepA8, in Shigella flexneri isolated in the United States, 2016

A qepA8+ Shigella flexneri was cultured from the stool of a traveler returning from India and East Asia. This chromosomally encoded qepA variant, has a six-base insertion, and may have been mobilized as part of a complex IS1-mediated composite transposon including catA1, aadA1, and blaOXA-1. In laboratory E. coli, qepA8 alone only conferred decreased ciprofloxacin susceptibility; however, it may work in combination with additional mechanisms to confer clinical resistance.