Identification of Determinants that Allow Maintenance of High-Level Fluoroquinolone Resistance in Acinetobacter baumannii

Transposon (mTn10 and/or himar-1) banks were created in the WT A. baumannii strain (ATCC 17978UN) and three high-level fluoroquinolone resistant strains harboring mutations in the GyrA and TopoIV fluoroquinolone targets as well as mutations that increase expression of drug resistance-nodulation-division (RND) efflux pumps (gyrAparCadeS (GPS), gyrAparCadeN (GPN), and gyrAparCadeL (GPL)). These banks were first sequenced to determine library saturation and then sequenced after culturing them for 7-8 generations in the absence and presence of comparable growth inhibiting levels of ciprofloxacin to identify mutants with altered drug sensitivity.